Apply the A1Z26 cipher
Map each letter to its alphabet position (A=1, B=2, ..., Z=26) and back. Pick the separator that fits your puzzle format. Runs locally in your browser.
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How to use A1Z26
Each letter becomes its position in the alphabet. Words are separated by double spaces; letters inside a word are joined with the chosen separator.
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Pick a mode
Encode produces numbers; decode parses them back into letters.
Bytes flow through
TextEncoder/TextDecoderfor predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.modeUTF-8TextEncoderlosslesslivemode · raw bytesencode · UTF-8encode | decode
loaded · UTF-8MIME · ready - 02
Choose a separator
Dash, space, comma, or period — match whatever format the puzzle expects.
Hash and signature operations call
crypto.subtlefrom the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.sepWeb Cryptosubtledeterministiclivesep · options- · live8-5-12-12-15
options applied · livelive - 03
Type or paste input
When encoding, type letters; when decoding, paste numbers in any common separator.
Options re-run instantly through
useEffect+useMemo— switching URL-safe mode or padding doesn’t re-encode from scratch.inputmemoisedoptionsinstantreactiveinput · encodedtext · readyHELLO WORLD
encoded · livelossless - 04
Copy or download
One click to clipboard. Download as .txt.
Copy uses the Async Clipboard API; downloads ship via
Blobwith the appropriate MIME (text/plain,image/png, …) so external tools recognise them.exportclipboardblobMIME-correctclient-sideout · copiedready · done8-5-12-12-15 23-15-18-12-4
shipped · ready to shipsuccess
Encoding without surprises
Always UTF-8 first
Use TextEncoder / TextDecoder for bytes ↔ string conversion. btoa alone breaks on non-ASCII.
URL-safe vs standard Base64
Standard uses +, /, =; URL-safe swaps to -, _, no padding. Don’t mix them.
Hashes aren’t passwords
SHA-256 is fast; that’s good for fingerprints, bad for passwords. Use bcrypt / argon2 for credentials.
Watch padding rules
Some decoders are strict about = padding, others auto-pad. If round-trips fail at exactly 1 or 2 bytes, check padding.
Use Web Crypto for keys
Generate cryptographic keys via crypto.subtle, never Math.random. The latter is predictable.
JWT decode ≠ verify
Decoding a JWT just splits and base64-decodes. Verification needs the issuer’s public key / shared secret.
When to use A1Z26
Beginner CTFs, ARGs, escape rooms.
Beginner CTFs
Common warm-up cipher in entry-level challenges. Output round-trips losslessly with the matching decoder — both run client-side, so end-to-end testing happens in a single tab. Encoding flows through TextEncoder for predictable UTF-8 semantics.
RFC-compliantARG puzzles
Number streams hidden in alternate reality games. Web Crypto's subtle.digest produces output that matches OpenSSL, GPG, and Node's crypto module byte-for-byte. That makes the result trustworthy as a content fingerprint, ETag, or integrity check.
OpenSSL-matchedEscape rooms
Decode lock combinations from posted text clues. Pairs cleanly with HMAC, JWT, and signed-URL workflows where bit-level correctness matters. The browser's crypto stack is FIPS 140-validated in Chrome and Firefox, so it's production-grade.
losslessTeaching kids
Simple, hands-on intro to ciphers. Output uses canonical RFC 4648 / 7515 alphabets so curl, openssl, and any standards-compliant decoder accept it as input. URL-safe variants drop padding for tokens that travel in query strings.
byte-identicalQuick obfuscation
Hide an answer in a numeric stream. Heavy hashing runs through useMemo so large inputs don't block typing. PBKDF2, bcrypt, and Argon2 expose configurable cost factors — tune for your threat model, not the default.
spec-gradeCross-implementation
Verify A1Z26 code in other languages. Same input plus same options always yields identical bytes. That's the foundation for content-addressed storage (IPFS, Git, S3 ETags) and means the output is safe to commit to fixtures.
production-readyFrequently asked questions
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