Encoding
Encoders and decoders for everyday formats
Base64, URL, JWT, hex, binary, Unicode escape, HTML entities. Paste in, read out, done. All processing happens in your browser — input never leaves your machine.
Integer Base Converter
Convert whole numbers between binary, octal, decimal, hex and any base from 2 to 36. Exact for values above 2^53, where parseInt quietly rounds.
Base64 Encode & Decode
Free online Base64 encoder and decoder. UTF-8 safe, works offline, runs entirely in your browser.
URL Encoder & Decoder
Encode and decode URL components per RFC 3986. UTF-8 safe, runs in your browser.
JWT Decoder
Inspect JSON Web Tokens in your browser. Header, payload, expiry. No key required, no data sent.
HTML Entity Encoder / Decoder
Encode/decode HTML entities (&, <, >, named, numeric, hex). Full HTML5 entity set.
Hex Encode / Decode
Convert text to and from hexadecimal bytes. UTF-8 safe — handles emoji, Vietnamese, CJK. Configurable separator and 0x prefix.
Binary Encode / Decode
Convert text to and from 8-bit binary. UTF-8 safe. Configurable byte separator.
Unicode Escape / Unescape
Convert text to \uXXXX or \u{XXXXX} escapes and back. Handles surrogate pairs for emoji. Output JSON-safe or ES2015 syntax.
HTTP Status Codes & MIME Types
Searchable reference for every common HTTP status code (what it really means) plus file-extension → MIME type lookup. Instant filter, works offline.
AES Text Encrypt / Decrypt
Encrypt or decrypt a piece of text with a password, using AES-256-GCM and PBKDF2. Runs in your browser — nothing is uploaded.
JWT Sign & Verify
Sign a JWT with HS256/384/512 or RS256/ES256, and verify a token against a secret or public key — signature, expiry and alg:none checked separately. Runs in your browser.
X.509 Certificate Decoder
Inspect a PEM or DER (.cer/.crt/.der) X.509 certificate — subject, issuer, validity, SAN, key usage, fingerprints. Certificate chains parsed in order. Runs in your browser.
Choosing between these tools
Encoding is not encryption. Base64, hex, URL-percent and HTML-entity encoding all exist to move bytes safely through a channel that would otherwise mangle them — an email header, a query string, an HTML attribute. Anyone can reverse them, so never use them to hide a secret.
Pick by the channel, not by taste. Use URL encoding for anything going into a query string or path segment; HTML entities when text has to survive inside markup; Base64 when binary data must ride inside a text-only field; hex or binary when you are reading a value byte by byte. The JWT decoder is a special case — it splits a token and shows you the claims, which is how you check an expiry or an audience without trusting the issuing app.
The HTTP status and MIME reference is here for the same reason the converters are: it answers the question you actually had, which is usually whether a 302 or a 307 is correct, or which Content-Type a browser will honour. Everything on these pages runs in your browser, so the text you paste never reaches a server.