CacheSleuth

Reverse-engineer .gwc cartridges

Upload a Wherigo cartridge and walk its zones, items, and Lua to reveal hidden coordinates without playing the cartridge in the field.

Waldmeister code → coordinates

Decode the Reverse Wherigo cartridge format used by Waldmeister puzzles. Paste a code, get the coordinates.

Identify a symbol on a page

Hundreds of code charts (semaphore, Morse, Maritime flags, runes, Braille…) — find the one that matches the marks in your puzzle.

Every coord format, one screen

Convert between DD, DDM, DMS, UTM, MGRS, Plus Codes, Geohash, Maidenhead, Mapcode, OSGB, and more — with a map and nearby-cache search.

Measure between two points

Compute the great-circle distance, bearing, and midpoint between two coordinates. Map preview included.

Project a coord by bearing & distance

Given a starting coordinate, a bearing, and a distance, find the destination point. Useful for multi-stage caches.

Three known angles, one unknown point

Solve for an unknown point given bearings from three known coordinates.

Reverse, sort, case-flip, dedupe…

A swiss-army knife of text transformations: reverse letters or words, sort lines, change case, strip whitespace, and more.

Decode element symbols in a clue

Look up element names, symbols, atomic numbers — and decode messages spelled with element symbols (Fe-N → "FeN").

Plan a cache near other listings

Check the 0.1-mile spacing rule against existing caches before you submit a new listing.

Featured

Type a message, supply optional keys / pad / numbers, and the Multi Encoder produces every reversible cipher and variant we can generate (Caesar, Bacon in every style, Morse, Atbash, Vigenère, Base64, and more), each with a round-trip check so you know exactly what got encoded.

Featured

Automatic cipher identifier. Paste an unknown ciphertext and we analyze its charset, frequency, index of coincidence, bigrams, and repeat patterns to recommend the most likely cipher with deep-link buttons into the matching solver.

Featured

Snap a photo or upload an image of a single glyph from an unknown symbolic alphabet (Pigpen, Dancing Men, Aurebesh, Klingon, Daedric, dozens of constructed-language scripts and historical ciphers) and the identifier compares it against thousands of reference glyphs to suggest which code it most likely belongs to. Pairs naturally with the Code Tables to confirm and decode.

Featured

Upload a picture of a coded message written in a symbol alphabet and read it back to letters. The decoder finds each glyph, matches it against the chosen code's reference symbols, and checks the result against a dictionary and coordinate patterns. Works best on clean, evenly spaced, high-contrast images.

Map Tools

Calculate coordinates from day1976 Reverse Wherigo codes, or create codes from cache coordinates.

Map Tools

Create geocache geoart from posted and final coordinates, validate distance rules, choose cache-type icons, and export GPX or CSV files.

Map Tools

Find possible geocache coordinates when one to three digits are missing from a DDM coordinate.

Map Tools

Batch convert GPS coordinates between DDM, DD, DMS, UTM, MGRS, Plus Code, Reverse Wherigo, OSGB, GeoHex, Geo3x3, Maidenhead, NAC, Geohash, Mercator, and antipode.

Map Tools

Map a list of GPS coordinates and calculate segment and total distances between points.

Map Tools

Calculate the intersection points of two circles from center coordinates and radii.

Map Tools

Find where two bearing lines intersect using two known coordinate points and a bearing from each.

Map Tools

Calculate the intersection point of three circles from center coordinates and radii.

Map Tools

Find where two geodesic lines intersect. Lines are drawn from A to B and C to D.

Map Tools

Find the antipode (the point diametrically opposite through the center of the Earth) for any GPS coordinate, with side-by-side maps of your point and its antipode.

Map Tools

Calculate the center, area, and perimeter of a triangle defined by three GPS coordinates.

Map Tools

Calculate the geographic centroid (center point) of an arbitrary list of coordinates using a 3D cartesian average.

Map Tools

Calculate the center point and radius of a circle passing through three GPS coordinates.

Map Tools

Average multiple GPS coordinate readings of the same location into a single best-estimate coordinate, with the spread of the readings.

Map Tools

Calculate the distance to the horizon for an observer at a given height, accounting for Earth's curvature and optional atmospheric refraction, plus the line-of-sight range to a raised object.

Map Tools

Convert a coordinate from one geodetic datum to another using a 7-parameter Helmert transformation, then view the shifted point on the map.

Map Tools

Calculate where a line defined by two GPS points intersects a circle defined by a center point and radius.

Map Tools

Given a line through two points and a third point off the line, find the foot of the perpendicular (the nearest point on the line), plus the cross-track and along-track distances.

Map Tools

Calculate the intersection of a bearing projected from one coordinate point with a line segment defined by two other coordinate points.

Map Tools

Calculate the geodesic area, perimeter, and centroid (center of gravity) of a polygon or quadrilateral defined by a list of coordinates.

Map Tools

Work out your location by measuring the compass bearing to three known coordinate points, then crossing the back-bearings to fix your position.

Map Tools

Calculate the rhumb line (constant compass bearing) course and distance between two coordinates, compared with the great-circle path.

Map Tools

Divide the line between two coordinates into a number of equal segments and list every intermediate point along the way.

Map Tools

Solve geocaching formulas with letter variables. Put math in square brackets, give each variable a value or a range, and get every result at once. Supports cross sums, word values, trig, roots, factorials, constants, exact modular and bitwise math, and references between formulas.

Map Tools

Calculate geocache coordinates from a formula with A-Z variables and bracketed math. Variables can be fixed values, ranges, or sets that expand to every combination, with each result parsed and mapped.

Map Tools

Calculate coordinates from the Multi Location Maze 11-character code, or create a code from cache coordinates.

Map Tools

Compute the Munroe (xkcd) geohash coordinate from a date, your graticule, and that day's Dow Jones opening, with the worldwide globalhash and an interactive map.

Code Tables

View every supported geocaching code table example in one place using custom text.

Cipher Tools

Add a numeric key to each letter's position to shift it, a classical generalization of Caesar where the shift can vary per character. Custom alphabets supported.

Cipher Tools

German WWI field cipher (1918) combining a 5×5 Polybius square (using only ADFGX as coordinates, easy to send by Morse) with a keyword-based columnar transposition.

Cipher Tools

Successor to ADFGX with a 6×6 square that includes digits 0–9. Used by the German army in 1918 until cracked by French cryptanalyst Georges Painvin.

Cipher Tools

Each letter's position is multiplied by one key, then offset by another, modulo 26, the affine map of monoalphabetic ciphers. Caesar is the special case where the multiplier is 1.

Cipher Tools

Hebrew kabbalistic substitution cipher that splits the alphabet in half and swaps the corresponding letters of the two halves. A close cousin of Atbash.

Cipher Tools

AMSCO is an incomplete columnar transposition cipher that fills a keyword-ordered grid by alternating one and two letters per cell, then reads the columns in key order.

Cipher Tools

ASCII-85 and Base85 encoder and decoder for converting text to and from Adobe-style ASCII85.

Cipher Tools

Hebrew substitution cipher that reverses the alphabet, A↔Z, B↔Y, C↔X, appearing in the Book of Jeremiah. The simplest reciprocal cipher.

Cipher Tools

Polyalphabetic Vigenère variant that extends the keyword with the plaintext (or ciphertext) itself, so the running key never repeats. Configurable alphabets and keyword. Includes an automatic solver to crack the keyword from ciphertext.

Cipher Tools

Francis Bacon's 1605 binary cipher hides a message inside an apparently innocent text using two letterforms (or two typefaces) per letter. Includes Bacon's distinct and merged variants plus puzzle-style key options.

Cipher Tools

Reciprocal Vigenère variant where the same operation encrypts and decrypts. Named after Admiral Sir Francis Beaufort, who based it on Giovanni Sestri's earlier work. Includes an automatic solver to crack the keyword from ciphertext.

Cipher Tools

Close cousin of Beaufort that reverses the subtraction direction (key minus plaintext). Used on Confederate-era cipher disks during the American Civil War. Includes an automatic solver to crack the keyword from ciphertext.

Cipher Tools

Felix Delastelle's fractionating cipher: each letter splits into two coordinates on a 5×5 Polybius square, coordinates are interleaved across a period, and read back as new letters.

Cipher Tools

Decode book ciphers and Ottendorf-style references by selecting pages, lines, words, or characters from a pasted source text.

Cipher Tools

Reversible block-sorting transform that rearranges text into runs of similar letters. Used inside the bzip2 compressor and as a puzzle scrambler that decodes cleanly back.

Cipher Tools

Simple transposition that writes the plaintext into a rectangular grid row by row, then reads it back column by column. Quick to spot when text length is a perfect square.

Cipher Tools

Italian 19th-century swap cipher used by the Carbonari secret society in the lead-up to Italian unification, pairing letters around a central pivot.

Cipher Tools

John F. Byrne's 1918 two-disk cipher in which both alphabets permute themselves after every letter. Byrne offered cash prizes for breaking it; the algorithm wasn't published until 2010.

Cipher Tools

Plaintext is written into a grid below a keyword, then read out column by column in the order given by the keyword's letter ranks. Configurable padding and alphabet.

Cipher Tools

Columnar transposition applied twice with two different keywords. Used by Allied and Axis intelligence services through World War II for medium-grade traffic.

Cipher Tools

Configurable Enigma rotor machine simulator with 13 models, ring settings, start positions, reflectors, plugboard pairs, and foreign-character handling.

Cipher Tools

Felix Delastelle's digraph cipher that operates on letter pairs using four 5×5 squares, two filled with a keyed alphabet and two with the standard alphabet.

Cipher Tools

Plaintext is converted to Morse, regrouped in threes (with separators), then each three-symbol group is looked up in a keyed alphabet. Used by US forces in World War I.

Cipher Tools

Encrypt and decrypt the Grandpré cipher using a configurable letter grid, random homophone choices, and coordinate-pair output.

Cipher Tools

Vigenère with a numeric key (digits 0–9) instead of a letter keyword, so each plaintext letter shifts by the matching digit. Supports autokey mode and custom alphabets. Includes an automatic solver to crack the numeric key from ciphertext.

Cipher Tools

Lester Hill's 1929 polygraphic cipher: plaintext blocks are multiplied by a 2×2 matrix key modulo 26, the first cipher to operate on more than three letters at a time.

Cipher Tools

One of the earliest substitution ciphers, described in the 4th-century Sanskrit Kama Sutra. The 26 letters are paired so each letter encrypts to its partner and vice versa.

Cipher Tools

Shift each letter to a neighbor on a physical keyboard layout, left, right, up, or down. Supports QWERTY, AZERTY, and QWERTZ layouts.

Cipher Tools

Caesar shift built on a keyed alphabet: the keyword's unique letters appear first, then the rest of the alphabet, and the whole thing is rotated.

Cipher Tools

Each plaintext letter's position is multiplied by a key (coprime with 26) modulo 26, a close cousin of Caesar that scrambles instead of just shifting.

Cipher Tools

Encode plaintext into Morbit cipher digits, or decode Morbit ciphertext back to text, using a 9-letter keyword or 1-9 permutation key.

Cipher Tools

Russian Nihilist cipher combining a Polybius square with a numeric keyword. Each plaintext letter and each keyword letter are converted to two-digit Polybius coordinates and added together to produce the ciphertext.

Cipher Tools

Encode and decode numeric homophonic ciphers with an A-Z key where each letter may map to one or more exact number tokens.

Cipher Tools

The only mathematically unbreakable cipher when the key is truly random, as long as the message, and used exactly once. Generate a fresh pad or supply your own.

Cipher Tools

Italian Renaissance cipher developed by Pope Innocent X's secretary Matteo Argenti and named after the Pizzini family, where letters map to numbered positions in a keyed grid.

Cipher Tools

Charles Wheatstone's 1854 digraph cipher worked on letter pairs using a keyed 5×5 grid. Adopted by the British in the Boer War and World War I.

Cipher Tools

Morse-based cipher in which dots, dashes, and separators are each replaced by one of several substitute characters, masking the underlying Morse pattern.

Cipher Tools

Each letter is encoded as the row/column coordinates of its position in a 5×5 (letters) or 6×6 (letters + digits) grid. Supports keyed alphabets and custom coordinate labels.

Cipher Tools

Giovanni Battista della Porta's 1563 reciprocal polyalphabetic cipher. The keyword chooses one of 13 alphabet pairings, and the same operation encrypts and decrypts. Includes an automatic solver to crack the keyword from ciphertext.

Cipher Tools

Ragbaby is a keyed periodic substitution cipher. A keyword builds a 24 letter mixed alphabet, then every letter is shifted forward by a number that counts up across the words of the message.

Cipher Tools

Write the plaintext zig-zagging down and up across a chosen number of rails, then read it off row by row. Configurable rail count and starting offset.

Cipher Tools

Educational RC4 stream cipher. Enter a key to generate a pseudo-random keystream and XOR it with your text. Output as hex or Base64. Encryption and decryption are the same operation.

Cipher Tools

Shift each letter by a chosen amount, with one-click presets for ROT13, ROT5, ROT18, and ROT47 covering letters, digits, and the full printable ASCII range.

Cipher Tools

Rotate text written into a grid 90° left or right, handy for puzzle text laid out in non-standard reading orders. Configurable column count and padding.

Cipher Tools

Caesar-style rotation that lets you choose exactly which characters get shifted and which pass through untouched. Useful for puzzles that mix cipher and plain text.

Cipher Tools

Writes the plaintext into a grid and reads it back along a chosen path (spiral, diagonal, or zig-zag) instead of plain columns.

Cipher Tools

Educational RSA demo using tiny primes and BigInt math. Generate a key pair from two primes, then encrypt and decrypt text or a single number. For learning and puzzles only, not for real security.

Cipher Tools

Vigenère-style cipher where the key is a long passage of natural text (a book, a poem) rather than a short repeated keyword, defeating standard Kasiski analysis.

Cipher Tools

Ancient Spartan transposition cipher: text wrapped around a cylinder of a specific diameter, then unwrapped, scrambles into a regular column rotation.

Cipher Tools

Solitaire (Pontifex) is a hand cipher designed by Bruce Schneier that uses an ordered deck of 54 cards, including two jokers, to generate a keystream for encrypting and decrypting messages.

Cipher Tools

Soviet-era fractionating cipher mapping common letters to single digits and rare ones to two-digit codes. Often used as an additive over a one-time pad in VIC-style ciphers.

Cipher Tools

Map each plaintext letter to a custom target letter using a keyed alphabet, the foundation under almost every monoalphabetic cipher in this list.

Cipher Tools

Felix Delastelle's three-dimensional extension of Bifid. Each letter gets three coordinates from a 27-character cube, interleaved across a period before being read back.

Cipher Tools

Johannes Trithemius's 1508 progressive Caesar, each letter shifting by one more than the previous. The first published polyalphabetic cipher and the direct ancestor of Vigenère.

Cipher Tools

German WWI double columnar transposition variant. Famously broken by French cryptanalysts in 1914 within weeks of its introduction.

Cipher Tools

The classic 1553 polyalphabetic cipher: each plaintext letter is Caesar-shifted by the corresponding letter of a repeating keyword. Considered unbreakable for three centuries. Includes an automatic solver to crack the keyword from ciphertext.

Cipher Tools

Soviet KGB hand cipher used by spy Reino Häyhänen in the 1950s, combining a straddling checkerboard, two transpositions, and a daily key. The strongest hand cipher ever fielded.

Code Tools

Geocaching code that maps each letter to a unique three-symbol group. Supports the canonical alphabet, custom carriers, or auto-detected three-character patterns.

Code Tools

Find every word and multi-word phrase that can be made from a set of letters. Multi-word phrase anagrams, single-word anagrams, and a 'words from these letters' subset mode. Toggle between a common-words dictionary and a 235,000-word full dictionary. Solves instantly in your browser, no server round-trips.

Code Tools

Three-character code built from forward slash, pipe, and backslash symbols. Each letter is encoded as a group of three; supports custom carriers and auto-detection.

Code Tools

The 5-bit telegraph codes that preceded ASCII, ITA1 (Baudot) on early teleprinters and ITA2 (Baudot–Murray) on Western Union and TWX networks.

Code Tools

Convert words to the calculator numbers that spell them upside down, or flip a number to read the hidden word. Uses the classic seven-segment letters from the word BEGHILOS.

Code Tools

Convert between text, Brainf*ck, Ook!, and Short Ook! code, with a small interpreter.

Code Tools

Geocaching code that represents each letter as a small grid of dashes and pipes, visually similar to Chinese hanzi strokes, hence the name.

Code Tools

Encodes letters as clock-face hours with AM/PM markers and "00" as a word separator. Often appears in geocaching puzzles using clock imagery.

Code Tools

Encode text as colored-squares blocks where each square has a binary value (1, 2, 4, 8, 16) summing to a letter A-Z. Recolor every value, toggle numbers, resize blocks, and export a PNG or share link for geocaching puzzles.

Code Tools

Convert text to COW code and execute COW programs back into text.

Code Tools

Ten-bit punched-card-style code where each character is a binary string. Output can be ASCII text or the equivalent decimal numbers.

Code Tools

DTMF (Dual-Tone Multi-Frequency) maps each phone-keypad press to a pair of audio frequencies. Only the 16 keypad characters are valid input: digits 0-9, letters A-D, *, and #. Any other character in the plaintext (letters E-Z, spaces, punctuation) is silently dropped.

Code Tools

Convert text typed on one keyboard layout as if it had been typed on the other (QWERTY ↔ Dvorak). Useful when puzzle text was prepared on the wrong layout.

Code Tools

Count enclosed areas in uppercase letters, lowercase letters, and numbers with open or closed 4 handling.

Code Tools

Cooke and Wheatstone's 1837 telegraph used five magnetic needles pointing left or right to spell out one of 20 letters across two wires.

Code Tools

The substitution cipher from Edgar Allan Poe's 1843 short story "The Gold-Bug," where the buried-treasure cryptogram is solved by frequency analysis on the page.

Code Tools

Translates each letter to a unique syllable in the Hodor language from HBO's Game of Thrones, where the character can only say his own name.

Code Tools

Three-character syllabic code based on the muffled speech of Kenny McCormick from South Park, mapping each letter to a sequence of m/f/p sounds.

Code Tools

Convert letters to numbers and numbers back to letters using A=1 through Z=26.

Code Tools

International Morse code with optional puzzle variants: reverse the sequence, swap dots and dashes, or both. Common transformations in mystery caches.

Code Tools

Decode run-on Morse code without separators by branching possible letter groupings and exploring viable translations.

Code Tools

Encode text to Nak Nak code and decode Nak syllables back to text.

Code Tools

Encode and decode messages with the World War II Navajo code talkers' alphabet, where each English letter is spoken as a Navajo word whose English meaning starts with that letter.

Code Tools

Convert letters or keypad line number paths into Number Pad Lines images.

Code Tools

PLANET (Postal Alpha Numeric Encoding Technique) maps each digit 0-9 to a 5-bar short/tall (i/I) pattern, framed by tall bars. Auto-detects two non-standard symbols (e.g. ./|, a/b, x/o) and tries both orientations.

Code Tools

POSTNET (Postal Numeric Encoding Technique) maps each digit 0-9 to a 5-bar short/tall (i/I) pattern, framed by tall bars. Auto-detects two non-standard symbols (e.g. ./|, a/b, x/o) and tries both orientations.

Code Tools

Encode and decode internationalized domain names with RFC 3492 Punycode. Unicode labels become ASCII with an xn-- prefix, and back again.

Code Tools

A nine-segment digital display alphabet, think calculator-style segments extended to cover the full alphabet. Includes matching symbol images for each character.

Code Tools

Convert Qwerty keyboard characters to row and column coordinate pairs.

Code Tools

Shift letters, numbers, and optional special characters across Qwerty keyboard rows.

Code Tools

Encode and decode strings written in segment-display notation. Each character is described by the set of segment labels (A, B, C, …) that are lit. Supports 7-, 9-, 14-, and 16-segment displays.

Code Tools

Code in which each letter is encoded as a group of slashes and pipes ( / and | ). A common building block in geocaching cipher puzzles.

Code Tools

Text steganography that disguises a secret message as spam-style prose, a fake PGP armor block, or a run of spaces and tabs. Optional password layer. Encode and decode entirely in your browser.

Code Tools

Convert text to and from spelling-alphabet code words. Includes the NATO/ICAO alphabet (Alfa, Bravo, Charlie), police (Adam, Boy, Charles), Western Union, RAF, Able Baker, and Dutch, German, Swedish, and Russian variants.

Code Tools

Decode or encode the Spirit Mars rover DVD code, a variable-length line and dash alphabet used on The Planetary Society DVD carried by Spirit.

Code Tools

Convert Tap Code between letters, numeric row-column pairs, and dot groups.

Code Tools

Encode and decode the TAPIR substitution table used by the DDR MfS and NVA, including the numeric mode used for digits and punctuation.

Code Tools

Drum-language code that uses forward slashes and backslashes to represent letters as drumbeat patterns, adapted from African talking-drum traditions.

Code Tools

Find dictionary words from T9 predictive text digit sequences.

Code Tools

Flip text upside down using Unicode characters that resemble rotated letters, numbers, and punctuation. Flip a message, then unflip it to read the original.

Code Tools

Old-style mobile phone keypad text input: 2=A, 22=B, 222=C, 3=D, etc. Decodes from repeated key presses, key/position pairs, or directional sequences.

Code Tools

Render Logo-style vector path commands such as FD, BK, LT, RT, PU, and PD as an inspectable SVG drawing for geocaching puzzles, with text encoding, rotation, flips, export, and share links.

Code Tools

Encode letters, numbers, and punctuation as ITA2/Baudot-style five-bit color blocks in an X&Y-inspired visual code, with PNG/SVG export and share links for geocaching puzzles.

Code Tools

Turn plain text into glitchy Zalgo text by stacking Unicode combining diacritical marks, with an intensity control. Clean Zalgo text back to readable characters.

Number Tools

Two different numbers are amicable when each one equals the sum of the other's proper divisors, like 220 and 284. Check any number to find its amicable partner if it has one, or list every amicable pair up to a limit for puzzle use.

Number Tools

An Armstrong (or narcissistic) number equals the sum of each of its digits raised to the power of the digit count, like 153 = 1^3 + 5^3 + 3^3. Check any number to see its full digit-power breakdown and verdict, or list every Armstrong number up to a limit for puzzle use.

Number Tools

An automorphic number is one whose square ends in the number itself, like 76 because 76 squared is 5776. Check any number to see its square with the matching tail highlighted and the verdict, or list every automorphic number up to a limit for puzzle use.

Number Tools

Encode and decode Babylonian numerals, the sexagesimal (base 60) system of stacked tens and units wedges. Enter a number to see its cuneiform glyphs and place values, or read a numeral back to decimal.

Number Tools

Encode positive whole decimal numbers as Binary-Coded Decimal nibbles, or decode BCD bit groups back to decimal digits for geocaching and logic puzzles.

Number Tools

Encode and decode Base100 emoji streams. Each UTF-8 byte maps to one emoji codepoint in the canonical U+1F3F7 to U+1F4F6 range.

Number Tools

Encode and decode text using the standard RFC 4648 Base32 alphabet (A–Z, 2–7). Often seen in TOTP secrets, QR codes, and DNS-safe identifiers.

Number Tools

Encode and decode text using Base58. Choose between the Bitcoin alphabet (123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz) and the Flickr alphabet (lowercase before uppercase). Base58 omits visually ambiguous characters like 0, O, I, and l.

Number Tools

Encode and decode text using Base62. Supports both 0-9A-Za-z and 0-9a-zA-Z alphabet orderings.

Number Tools

A large integer calculator for decimal, hexadecimal, octal, and binary values with standard arithmetic, modular arithmetic, bitwise operations, powers, and modular inverse.

Number Tools

Catalan numbers count many things: valid bracket sequences, binary trees, polygon triangulations, and more. List the first terms, look up C(n) for any index, or test whether a number is a Catalan number and see its index. Computed with arbitrary precision.

Number Tools

The Collatz conjecture, also called the 3n+1 problem, repeatedly halves even numbers and turns odd numbers into 3n+1 until reaching 1. Trace the full hailstone sequence for any starting number, see its step count and peak value, or search for the starter with the longest sequence up to a limit.

Number Tools

Replace a number with the sum of the factorials of its digits, then repeat. The chain either lands on a fixed point called a factorion, falls into a number that is itself a factorion, or settles into a repeating cycle. In base 10 there are exactly four factorions: 1, 2, 145, and 40585. Trace the chain for any number and see its outcome.

Number Tools

Figurate numbers count dots arranged into regular shapes. Pick a type (triangular, square, pentagonal, hexagonal, or tetrahedral), list the first terms, look up the value at a given index, or test whether a number belongs to that family and see its index.

Number Tools

A Harshad (or Niven) number is one that is divisible by the sum of its own digits, like 18 which has digit sum 9 and 18 divided by 9 is 2. Check any number to see its digit sum, quotient, and verdict, or list every Harshad number up to a limit for puzzle use.

Number Tools

Kaprekar's routine sorts a number's digits high to low and low to high, then subtracts, and repeats until it locks onto 6174 for four digits or 495 for three digits. Trace the chain and step count for any number, and separately check or list Kaprekar numbers, whose squares split into two parts that add back to the number.

Number Tools

The reverse-and-add process flips a number's digits and adds it to itself, repeating until the result reads the same forwards and backwards. Most numbers reach a palindrome quickly, but some, like 196, resist for thousands of steps and are called Lychrel candidates. Trace the chain, palindrome, and iteration count for any number.

Number Tools

A Mersenne number is M(n) = 2 to the n, minus 1. List M(n) for a range of exponents and see which are Mersenne primes, look up M(n) for any exponent, or test whether a number is one less than a power of two and report its exponent. Computed with arbitrary precision.

Number Tools

A standalone integer number cruncher for geocaching puzzles: inspect parity, primality, factors, special number forms, base conversions, and evaluate BigInt worksheet expressions with variables and modular arithmetic helpers.

Number Tools

Encode and decode Cistercian numerals, the medieval monastic system that packs any number from 0 to 9999 into a single glyph built around one vertical stem. Enter a number to draw its glyph, or read the four positional digits back to decimal.

Number Tools

Solve cryptarithm and alphametic puzzles by assigning unique digits to letters in arithmetic equations and optional logical conditions.

Number Tools

Add or subtract days, weeks, months, and years from a date with leap-year aware Gregorian calendar math for puzzle deadlines, cache anniversaries, and date clues.

Number Tools

Calculate the exact number of days between two Gregorian calendar dates, with signed direction, absolute distance, inclusive span, and week/day breakdown.

Number Tools

Calculate the day of the week for a date, plus its day number within the year and leap-year status, using proleptic Gregorian calendar rules.

Number Tools

Convert decimal numbers to and from the D'ni base-25 number system from Cyan's Myst series. Type a number or tap the D'ni keypad to see the symbols rendered in the D'ni font, with a power-of-25 breakdown for geocaching puzzles.

Number Tools

Convert numbers between decimal, standard binary, and reflected binary Gray code. Gray code is an ordering of binary where two successive values differ in only one bit.

Number Tools

A happy number is one that eventually reaches 1 when you repeatedly replace it with the sum of the squares of its digits. Check any number to see its full digit-square chain and verdict, or list every happy number up to a limit for puzzle use.

Number Tools

Convert calendar date/time values to Julian Day numbers and back, including JPL-style month names, day-of-year input, decimal day/time forms, astronomical years, Modified Julian Date, and Unix time.

Number Tools

Encode and decode Maya numerals, the base-20 system of dots, bars, and a shell for zero. Enter a number to see its stacked glyphs and place values, or read a numeral back to decimal.

Number Tools

Calculate today's day number, convert a full date or month/day pair to an nth day of the year, and convert a day number back to a calendar date.

Number Tools

Four conversions in one tool: alphabetical index → number word, number word → alphabetical index, number → English spelling, and spelled-out English → integer. The alphabetical order uses the standard 0–100 ranking where eight = 1, eighteen = 2, eighty = 3, and zero = 101.

Number Tools

Reduce each letter of a word or phrase to a digit using the Pythagorean (1–9 cycle), Pythagorean (1–0 cycle), or Chaldean systems, then sum and reduce to a single-digit numerology value or digital root.

Number Tools

A perfect number equals the sum of its proper divisors, like 28 = 1 + 2 + 4 + 7 + 14. When that sum is larger the number is abundant, and when it is smaller the number is deficient. Check any number to see its proper divisors, their sum, and the classification, or list every perfect number up to a limit.

Number Tools

A pronic number, also called an oblong number, is the product of two consecutive integers: P(n) = n(n+1). List the first terms, look up P(n) for any index, or test whether a number is pronic and report its index. Computed with arbitrary precision.

Image & File Forensics

Upload an animated GIF of a blinking light or flashing signal and decode it into Morse code, then plain text. Brightness per frame is measured and timed automatically, with sliders to fine tune the on or off threshold and the dot or dash split.

Image & File Forensics

Upload a recording of Morse code beeps or listen live through your microphone and decode it into Morse and plain text. The dominant tone frequency and the timing are detected automatically, with sliders to fine tune the frequency, threshold, and dot or dash split.

Image & File Forensics

Create barcodes in Code 128, Code 39, and EAN-13 formats with configurable size and colors.

Image & File Forensics

Render binary into a picture: 1 bit per pixel black and white, or one byte per pixel grayscale. You can also upload an image and read its pixels back out as a row-major 0/1 bitstream with byte views.

Image & File Forensics

Upload an image file to read EXIF data. Supports JPEG, PNG, WebP, TIFF, HEIC/HEIF, AVIF and limited GIF support.

Image & File Forensics

Upload a file and this tool scans every byte for known file-type signatures hidden inside it, including extra data appended after the end of an image. Carve out each find and download it as its own file.

Image & File Forensics

Upload an animated GIF, WebP, APNG, or AVIF and split it into individual frames. View every frame side by side, inspect timing and dimensions, and download frames individually or as a ZIP.

Image & File Forensics

View any file as a hex dump with offsets, raw bytes, and an ASCII column. Extract printable strings from the whole file to surface hidden coordinates or clues.

Image & File Forensics

Non-destructive image color and pixel tools that reveal faint or hidden marks. Tweak brightness, contrast, saturation, hue, invert, threshold, isolate a channel, view a single bit plane, and flip, rotate, or stretch the picture.

Image & File Forensics

Hide text inside an image by tweaking the least-significant bits of its pixels, then download a lossless PNG. Reveal hidden messages from a stego image, with an automatic header read plus a raw LSB extraction mode for foreign puzzles.

Image & File Forensics

Upload a Magic Eye style autostereogram and reveal the hidden depth shape without crossing your eyes. Auto-detects the repeat period, then maps the match between the image and a shifted copy of itself into a visible figure.

Image & File Forensics

Create a wall-eyed text autostereogram (ASCII magic eye). Type a hidden message, pick random characters or real words for the background, and generate a block of monospace text whose secret words pop out at a different depth when you relax your eyes. Export as plain text or as a fixed-width monospace PNG.

Image & File Forensics

Create a custom QR code with configurable text, size, quality level, foreground, and background.

Image & File Forensics

Upload a QR code image file and scan the encoded text.

Image & File Forensics

Encode and decode Tupper's self-referential formula. Convert text, drawings, or images into the integer k for geocaching puzzle caches, and decode k back into a bitmap.

Image & File Forensics

Split a black-and-white secret image into two share images using a 2-out-of-2 visual secret sharing scheme. Each share looks like random noise on its own, but overlaying the two reveals the hidden picture.

Misc Tools

Paste cipher text and run 250+ decoders at once, Caesar, Vigenère, Atbash, Bacon, Polybius, Beaufort, Playfair, ADFGX, Morse, Base64, and dozens more, with optional keyword, alphabet, and number hints. Detects coordinates in multiple notations, surfaces possible plaintext words, and groups results by likelihood so the right answer rises to the top.

Misc Tools

Analyze character frequencies, word counts, letter counts, number counts, and symbol counts in a body of text.

Misc Tools

An interactive flowchart that walks through clues in puzzle text (letter patterns, character sets, common encodings) and points you toward the most likely solver.

Misc Tools

Encode HTML or text into JavaScript document.write output.

Misc Tools

Paste any symbol to identify its Unicode name, codepoint, HTML entity, Alt code, and puzzle-solving hints. Search by name, browse categories, compare confusable characters, and analyze symbol-heavy puzzle text.

Misc Tools

Unicode character lookup tool that maps each character in a message to its Unicode code point and name.

Misc Tools

Copyable HTML examples for creating geocache pages, including paragraphs, line breaks, centering, text styling, links, images, sizing, inline styling, and divs.

Misc Tools

Make your own printable geocache log sheets and log rolls sized to fit nano, bison tube, film canister, petling, and custom containers. Add a cache name, GC code, your own logo image, pick columns and line styles, optionally add a finder note for muggles, then save as PDF or PNG. Everything runs in your browser, nothing is uploaded.

Misc Tools

Bookmarklets that send highlighted text into the Multi Decoder, Multi Encoder, Cipher Identifier, Cryptogram Solver, Anagram Solver, Frequency Analysis, Unicode tool, and code tables, scrape every coordinate off a page onto the Map Coordinates List, plus shortcuts for coordinate conversion, GC/TB lookup, CacheSleuth search, text manipulation, geocaching user search, keyword search, and GeoCheck captcha entry.

Misc Tools

Convert ISBN-10 to ISBN-13 or ISBN-13 to ISBN-10, and look up ISBN details through Open Library with Amazon and Google fallback searches.

Misc Tools

Generate MD5, SHA-1, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256 hashes for text.

Misc Tools

Decode resistor color bands into resistance and tolerance values using the standard color code table.

Misc Tools

Spell words with chemical element symbols and view matching periodic table tiles.

Misc Tools

Translate text to and from CacheSleuth DNA code triplets using A, C, G, and T.

Misc Tools

Convert DNA or RNA sequences into amino acid sequences, inspect codons, and look up standard genetic code mappings.

Misc Tools

Decode and create Draw A Stickman Episode 1 custom message URLs.

Misc Tools

Convert a plain English message into Pig Latin.

Misc Tools

Translate text into Circular Gallifreyan and save the generated artwork as an image.

Games & Solvers

Enter the given 0s and 1s of a Binairo puzzle, also called Takuzu or Binary Puzzle, then solve the grid so each row and column holds equal counts of each digit, never three of the same digit in a row, and no two rows or columns alike. Click cells to set them and solve grids from 4 by 4 up to 10 by 10.

Games & Solvers

Place the islands of a Bridges puzzle, also called Hashiwokakero or Hashi, with their numbers and solve it so the islands are joined by straight bridges that never cross, with at most two bridges between a pair, each island carrying exactly its number of bridges, and the whole network connected. Click cells to set island numbers and solve grids up to 9 by 9.

Games & Solvers

Flip a coin, guess heads or tails, and track wins, losses, and choices.

Games & Solvers

Enter a Futoshiki puzzle, also called Hutoshiki or More or Less, by typing any given digits and clicking the greater-than and less-than signs between cells, then solve the Latin square so every row and column holds each number once while every inequality stays true. Works for grids from 4 by 4 up to 7 by 7.

Games & Solvers

An interactive Conway's Game of Life playground. Paint cells on a grid, step or play the B3/S23 simulation, and load patterns like the Glider, Blinker, Pulsar, and Gosper glider gun.

Games & Solvers

Build a Heyawake puzzle by carving the board into rooms and giving some rooms a black-cell count, then solve it so every numbered room holds exactly that many painted cells, painted cells never touch, the white cells stay connected, and no straight run of white cells crosses more than two rooms.

Games & Solvers

Type the number grid of a Hitori puzzle and solve it to find which cells to shade so that no number repeats among the unshaded cells of any row or column, no two shaded cells touch edge to edge, and all the unshaded cells stay connected. Works for grids from 4 by 4 up to 8 by 8.

Games & Solvers

Build a Kakuro puzzle, also called cross-sums, by marking the block cells and typing each across and down run total, then solve so every white cell holds a digit 1 to 9, each run uses different digits, and each run adds up to its clue. Works for grids up to 8 by 8 with a clickable block and clue editor.

Games & Solvers

Build a KenKen puzzle, also called Mathdoku or Calcudoku, by drawing its cages and entering each cage target and operation, then solve the Latin square so every row and column holds each number once and every cage hits its arithmetic target. Works for grids from 3 by 3 up to 7 by 7.

Games & Solvers

Build a Light Up puzzle, also called Akari, by marking the walls and their numbers, then solve it to place bulbs so every white cell is lit, no two bulbs shine on each other, and each numbered wall touches exactly that many bulbs. Click cells to set walls and numbers and solve grids up to 8 by 8.

Games & Solvers

Interactive logic grid solver for zebra and Einstein style puzzles. Set up your categories and items, mark relationships or enter clues, and watch it auto-deduce every forced cell across the grid.

Games & Solvers

Enter the known numbers of a magic square and solve the rest so that the whole square uses the distinct numbers 1 to n squared and every row, every column, and both diagonals add up to the same magic constant. Works for squares from 3 by 3 up to 5 by 5, completing the cells you leave blank.

Games & Solvers

Enter the guesses you have made and the black and white peg feedback for each, and the solver lists every code still possible and suggests the strongest next guess using a worst case minimizing strategy. Works for any number of positions and colors, with or without repeated colors.

Games & Solvers

Place the white and black pearls of a Masyu puzzle, also called Pearl, and solve it to draw the single closed loop through the cell centres. The loop runs straight through every white pearl and turns at every black pearl, with the matching turn and straight rules on the neighbouring cells. Works for grids up to 8 by 8.

Games & Solvers

Enter the row and column number clues of a nonogram, also called picross or griddler, and solve the hidden picture. The solver fills every cell that logic forces and falls back to a search when a puzzle needs a guess.

Games & Solvers

Enter a number pyramid, also called a number wall, with some blocks left blank, and the solver fills the rest. Every block equals the sum of the two blocks directly beneath it.

Games & Solvers

Type the numbered endpoints of a Numberlink puzzle, also called Arukone or Flow, and solve it to connect each pair with a path. The paths never cross or overlap and together fill every cell of the grid. Works for grids up to 8 by 8 with up to a dozen number pairs.

Games & Solvers

Type the island clues of a Nurikabe puzzle, also called Islands in the Stream, and solve it to shade the black sea. Every numbered cell becomes a white island of exactly that size, islands never touch, the sea is one connected region, and the sea has no 2 by 2 block. Works for grids up to 8 by 8.

Games & Solvers

Roll one or more six-sided dice with running totals. For chance-driven puzzles or just for fun.

Games & Solvers

Type the word you played and set each tile's premium square and any blanks to get the exact play score. Supports Scrabble English and Words With Friends tile values plus the all-tiles bingo bonus.

Games & Solvers

Enter the cards laid out in a game of SET by their number, color, shading, and shape, and the solver finds every valid set, where each of the four features is either all the same or all different across the three cards. Each found set is drawn out so you can spot it on the table.

Games & Solvers

Enter a Skyscrapers puzzle, the Latin square where edge numbers tell you how many buildings are visible looking down each row and column, then solve it so every row and column holds each height once and every clue is satisfied. Type the clues around the grid, add any given heights, and solve grids from 4 by 4 up to 7 by 7.

Games & Solvers

Type the number clues of a Slitherlink puzzle, also called Loop the Loop or Fences, and solve it to draw the single closed loop along the grid edges so that each numbered cell has exactly that many of its four sides on the loop. Works for grids up to 7 by 7 with a simple clue grid.

Games & Solvers

HTML Sudoku solver with hints, allowed values, singles, undo, reset, and serial puzzle loading.

Games & Solvers

Pick the number of disks and the peg labels, then get the full minimum move sequence for the Tower of Hanoi. The list shows every step in order and an animation walks through the solution.

Games & Solvers

Generate a word search grid from a list of words with optional diagonals and reversed words, or paste a grid and a word list to find where each word hides. Runs entirely in your browser.

Games & Solvers

Paste a nine by nine wordoku grid built from nine distinct letters and solve it with a backtracking sudoku engine. The solver also lists the diagonals and rows so you can spot the hidden themed word.