Codes & Ciphers
Encode and decode the classical ciphers taught in puzzle hunts, escape rooms and cryptography courses — from Caesar and Atbash to Playfair, Hill, ADFGVX and a working Enigma I — with the arithmetic shown for every letter, plus Morse, binary, Base32 and other codes. Free, no sign-up.
Codes & Ciphers
36 tools · free, no sign-up
Morse Code Translator
Translate text to Morse code and Morse code back to text. Supports letters, numbers, and punctuation with standard international Morse.
Binary Code Translator
Convert text to binary code and binary back to text. See each character's 8-bit representation and decode any binary string.
Caesar Cipher Encoder & Decoder
Encode and decode Caesar cipher messages with any shift (including ROT13) — plus a brute-force mode that shows all 25 shifts at once.
Pig Latin Translator
Translate English to Pig Latin and Pig Latin back to English — with the rules explained (consonant clusters, vowels, and 'way' endings).
Password Generator
Generate strong random passwords locally in your browser — choose length and character sets, with a strength estimate. Nothing is sent anywhere.
Vigenère Cipher Encoder & Decoder
Encode and decode Vigenère cipher messages with any keyword — with the letter-by-letter working shown and a history of the cipher.
Leet Speak Translator
Convert text to leet speak (1337 5p34k) and back — choose basic or advanced substitution levels and copy the result anywhere.
Atbash Cipher
Encode and decode the Atbash cipher, which swaps A↔Z, B↔Y and so on — one action works both ways, with the mirror alphabet and letter-by-letter working shown.
Rail Fence Cipher
Encode and decode the rail fence (zigzag) cipher with 2–10 rails and an optional offset — the zigzag drawn out, plus a brute-force decode across every rail count.
Affine Cipher
Encode and decode the affine cipher E(x) = (ax + b) mod 26 — with the modular inverse, the 12 valid values of a, letter-by-letter working, and a 312-key brute force.
Playfair Cipher
Encode and decode the Playfair cipher from any keyword — the 5×5 key square, the digraph preparation, and each pair's row, column or rectangle rule shown step by step.
Letters to Numbers (A1Z26) Converter
Convert letters to numbers (A = 1 … Z = 26) and numbers back to letters, with a choice of separators, a reversed alphabet (Z = 1), or zero-based numbering (A = 0).
Bacon Cipher
Encode and decode Francis Bacon's biliteral cipher in his 24-letter or the 26-letter alphabet, with A/B, 0/1 or custom symbols — and hide the code in a cover text.
Polybius Square Cipher
Encode and decode the Polybius square — letters as row-and-column numbers from 11 to 55, with an optional keyword square — plus the prisoners' tap code.
Substitution Cipher Solver
Solve cryptograms with letter frequencies, short-word and doubled-letter hints and a live guess grid — or encode and decode with a keyword or random substitution key.
Columnar Transposition Cipher
Encode and decode keyword columnar transposition — single or double, padded with X or left with irregular columns — with every grid and its column order drawn out.
Pigpen Cipher
Turn text into pigpen (Freemason's cipher) symbols and download them as SVG or PNG, or read a pigpen message with a clickable symbol keyboard and the key chart.
Enigma Machine Simulator
Simulate the Enigma I: rotors I–V, reflectors B and C, ring settings, plugboard and the double step — with rotor windows, a lamp board and every key press traced.
Hill Cipher
Encode and decode the Hill cipher with a 2 × 2 or 3 × 3 key matrix or keyword — invertibility checked mod 26 and the inverse key worked out by the adjugate method.
Password Strength Checker
Check a password on your device: entropy, common-password and dictionary matches, l33t, sequences, keyboard walks and dates, time to crack by attack, and specific fixes.
Beaufort Cipher
Encode and decode the Beaufort cipher and its variant from any keyword — the 26 × 26 square and the arithmetic for every letter shown.
Autokey Cipher
Encode and decode the Vigenère autokey cipher from a primer — the key builds itself from your message, with the square and every letter's sum shown.
Porta Cipher
Encode and decode the Della Porta cipher from any keyword — its 13 reciprocal alphabets shown, with the arithmetic for every letter worked out.
Four-Square Cipher
Encode and decode the four-square digraph cipher from two keywords — all four 5 × 5 squares shown, with the rectangle behind every pair of letters.
Bifid Cipher
Encode and decode Delastelle's bifid cipher with a keyed 5 × 5 or 6 × 6 Polybius square and a period — row and column digits shown for every block.
Trifid Cipher
Encode and decode Delastelle's trifid cipher with a keyed 3 × 3 × 3 cube and a period — layer, row and column digits shown for every block.
ADFGVX Cipher
Encode and decode the German ADFGX and ADFGVX ciphers — a keyed Polybius square, then a columnar transposition, with both stages shown.
Nihilist Cipher
Encode and decode the Nihilist cipher from a keyed Polybius square and an additive key — each letter's number, key number and sum worked out.
Book Cipher
Encode and decode a book cipher from any key text — words, first letters or letters, written as running numbers, line:word or page:line:word, with the lookup shown.
Scytale Cipher
Encode and decode the Spartan scytale transposition with any rod size — the message laid out on the rod, the unwound strip shown, and every rod size ranked to crack unknown text.
Route Cipher
Encode and decode route ciphers — write a message into a grid and read it along a spiral, column or zigzag route, for letters or whole words, with every cell numbered.
XOR Cipher
Encrypt and decrypt text with a repeating-key XOR on UTF-8 bytes — hex or Base64 output, every byte worked out in binary, and a search over all one-byte keys.
One-Time Pad
Generate a random letter pad, encrypt and decrypt text modulo 26 with the working shown, and see why reusing a pad breaks the cipher — a teaching aid, not secure messaging.
Base32, Base58 and Ascii85 Converter
Encode and decode Base32 (RFC 4648), Base58 (Bitcoin alphabet), Ascii85 (Adobe) and Z85 (ZeroMQ) for text or hex bytes, with the grouping and digits shown.
Phone Keypad Cipher
Encode text as multi-tap, key-and-press or T9 digits on the standard phone keypad and decode them again, with ranked word candidates for T9 and the keypad shown.
Cipher Identifier
Paste cipher text and see which cipher family it resembles — from its character set, index of coincidence, English letter pairs and key-length hints — with links to solvers.
Ciphers by Family
- Simple substitution. Caesar (with ROT13 and a brute-force view), Atbash, affine, Bacon, pigpen and a Substitution Cipher Solver for cryptograms. Each letter always becomes the same letter or symbol.
- Keyword (polyalphabetic) ciphers. Vigenère, Beaufort, Porta and Autokey, where a keyword changes the shift from letter to letter. Beaufort and Porta are reciprocal: one setting both encrypts and decrypts.
- Square and cube ciphers. The Polybius square turns letters into coordinates; Nihilist, Bifid, Trifid and ADFGVX build on it, and Playfair and Four-Square encrypt letters in pairs.
- Matrix and machine. The Hill cipher uses matrix multiplication mod 26, and the Enigma Machine Simulator models the Enigma I with rotors I–V, reflectors B and C, ring settings, the plugboard and double stepping.
- Transposition. Rail fence, columnar transposition, scytale and route ciphers rearrange the letters instead of replacing them.
- Keys from text, bytes and pads. The Book Cipher encodes words as positions in a shared text, the XOR Cipher works on bytes with a repeating key, and the One-Time Pad generates a random pad and shows why reusing one breaks it.
- Codes. The Morse Code Translator, Binary Code Translator, A1Z26 Converter, Phone Keypad Cipher for multi-tap and T9, the Base32, Base58 and Ascii85 Converter, Pig Latin and Leet Speak translators.
- Real security. The Password Generator and Password Strength Checker, both of which run on your device.
Identifying an Unknown Cipher
Faced with a message and no key, look at what the ciphertext is made of before you try anything. The Cipher Identifier does this for you: paste the text and it reports the character set, the index of coincidence, letter pairs and a likely key length, and says which family the message resembles. By hand, the table below is the same reasoning.
| The ciphertext… | Suspect | Try |
|---|---|---|
| Uses only dots and dashes | Morse code | Morse Code Translator |
| Uses only 0s and 1s in groups of eight | Binary ASCII | Binary Code Translator |
| Is numbers from 1 to 26 | A1Z26 | A1Z26 Converter |
| Is pairs of digits from 1 to 5 | Polybius square | Polybius Square Cipher |
| Is only the letters A, D, F, G, V and X | ADFGX or ADFGVX | ADFGVX Cipher |
| Is letters with English-like frequencies, just rearranged | A transposition | Rail fence, then columnar |
| Is letters with a shifted frequency pattern | Caesar or another monoalphabetic substitution | Caesar brute force, then the Substitution Cipher Solver |
| Is letters with a flattened frequency pattern | A polyalphabetic cipher | Vigenère with a guessed keyword |
| Ends in = signs or uses mixed letters and digits | Base32 or Base64-style encoding | Base Encoding Converter |
For Puzzles and Learning, Not Secrets
Every classical cipher on this shelf, except a correctly used one-time pad, can be broken with pencil-and-paper methods or a few seconds of computing — frequency analysis broke simple substitution over a thousand years ago, and Enigma traffic was read during the Second World War. They are excellent for teaching how encryption works, for puzzles and for escape rooms. To protect real information, use modern, audited encryption such as the encryption built into your device or messaging app.
The encoders, decoders and password tools run in your browser, so messages and passwords you type are not sent anywhere. For the number theory behind Hill, affine and modular ciphers, see the Math Calculators shelf, and for spelling a message out loud, the NATO Phonetic Alphabet Converter.
Frequently Asked Questions
- How do I decode a Caesar cipher without the key?
- Use the brute-force view in the Caesar Cipher tool. There are only 25 possible shifts, so it lists every one and the readable line is usually obvious at a glance. ROT13 is the shift of 13.
- What is the difference between a cipher and a code?
- A cipher transforms letters or symbols by a rule and a key — Caesar shifts each letter. A code replaces whole words or units with something else by a fixed table — Morse replaces each letter with dots and dashes and has no key. In everyday use the two words overlap.
- Is the Vigenère cipher secure?
- No. It resisted casual attack for centuries, but the repeating keyword leaves patterns that the Kasiski examination and frequency analysis exploit. A long message under a short key can be broken quickly. Autokey, which builds the key from the message itself, removes the repetition but is still breakable.
- Is a one-time pad really unbreakable?
- Yes, but only if the pad is truly random, at least as long as the message, kept secret, and never used twice. Reusing a pad lets an attacker combine two ciphertexts and strip the key away, which is why the One-Time Pad tool warns you. A repeating-key XOR cipher is not a one-time pad and is easy to break.
- Can the Enigma simulator decrypt real wartime messages?
- Yes, if you know the settings used — rotor order, ring settings, starting positions and plugboard pairs. Enigma is symmetric: with the same settings, typing the ciphertext gives back the plaintext. Without the settings, the simulator cannot find them for you.
- Are the passwords from the password generator safe to use?
- The Password Generator builds passwords on your device with your browser's cryptographic random number generator, and nothing is sent to a server. Use a long password and store it in a password manager.