All 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.

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.

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.

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.

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

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

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

Polyalphabetic Vigenère variant that extends the keyword with the plaintext (or ciphertext) itself, so the running key never repeats. Configurable alphabets and keyword.

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.

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.

Close cousin of Beaufort that reverses the subtraction direction (key minus plaintext). Used on Confederate-era cipher disks during the American Civil War.

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.

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.

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.

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

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.

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.

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

German WWII rotor machine simulator: pick rotors I–VIII, set ring positions, choose a reflector, and define plugboard pairs. The same settings encrypt and decrypt.

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

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.

Vigenère with a numeric key (digits 0–9) instead of a letter keyword — each plaintext letter shifts by the matching digit. Supports autokey mode and custom alphabets.

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.

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.

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

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.

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.

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.

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.

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

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.

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

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.

Giovanni Battista della Porta's 1563 reciprocal polyalphabetic cipher. The keyword chooses one of 13 alphabet pairings, and the same operation encrypts and decrypts.

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.

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.

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.

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.

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

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.

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

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.

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

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.

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

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

The classic 1553 polyalphabetic cipher: each plaintext letter is Caesar-shifted by the corresponding letter of a repeating keyword. Considered unbreakable for three centuries.

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

Manipulate text for puzzle solving with case changes, filtering, reversing, grouping, ROT transforms, replacement, file loading, saving, and content analysis.

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

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

Encode HTML or text into JavaScript document.write output.

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

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

Bookmarklets that shortcut coordinate conversion, GC/TB lookup, CacheSleuth search, text manipulation, geocaching user search, keyword search, and GeoCheck captcha entry.

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

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.

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

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

Convert element atomic numbers to symbols and names, or convert symbols and names back to atomic numbers.

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

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

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

Convert a plain English message into Pig Latin.

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

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

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

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

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

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

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

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.