Convert text and ASCII codes
Switch between text, ASCII decimal codes, and ASCII binary in either direction. Useful for teaching, debugging, and quick lookups. All processing runs locally.
72 105
How to convert ASCII
Four directions: text ↔ decimal codes and text ↔ binary. Codes use space separators by default; binary bytes are zero-padded to 8 bits.
- 01
Pick a direction
Encoding (text in) or decoding (numbers in).
Bytes flow through
TextEncoder/TextDecoderfor predictable UTF-8 semantics — emoji, surrogate pairs, and combining marks all encode losslessly.modeUTF-8TextEncoderlosslesslivemode · raw bytestxt→dec · UTF-8text → decimal
loaded · UTF-8MIME · ready - 02
Paste input
Text on the left, codes on the right — the placeholder shows the format.
Hash and signature operations call
crypto.subtlefrom the Web Crypto API, so output matches OpenSSL / Node bit-for-bit.inputWeb Cryptosubtledeterministicliveinput · optionsHi · liveHi
options applied · livelive - 03
Live convert
Codes are space-separated; binary is zero-padded to 8 bits.
Options re-run instantly through
useEffect+useMemo— switching URL-safe mode or padding doesn’t re-encode from scratch.livememoisedoptionsinstantreactiveout · encoded72 105 · ready72 105
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-sideok · copiedready · doneCopied
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 convert ASCII
Education, debugging, protocols, puzzles.
CS teaching
Demonstrate character → number mappings. 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-compliantProtocol debugging
Confirm wire bytes match expected ASCII. 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-matchedCTF puzzles
Quick decode of binary or decimal 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.
losslessEncoding bugs
Spot which byte sequence a glitch produced. 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-identicalEmbedded systems
Read sensor outputs that emit raw ASCII codes. 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-gradeSteganography
Hide messages in number streams. 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
Something missing?
Tell us what you need. We ship the top requests every two weeks.