Base64 Encoder/Decoder

Base64 Encoder/Decoder converts between raw text or binary and Base64 notation — the encoding that embeds binary data inside JSON, HTML, CSS, and URLs without breaking their syntax. The tool handles UTF-8 text correctly, so strings with emoji, CJK characters, and accented letters round-trip without mojibake. Encoding is something developers reach for in surprisingly many situations: embedding a small logo as a data URI in CSS to avoid an extra HTTP request, passing binary file content through a JSON API field, storing image uploads in localStorage, authorizing HTTP Basic Auth headers (which are Base64-encoded "user:password"), or transferring email attachments via MIME. The tool also decodes JWT payload segments, which are Base64url-encoded. Drop a file onto the input and get its Base64 representation instantly, useful for building data-URI sprites or testing API endpoints that accept inline binary. The decoder accepts both standard Base64 and the URL-safe variant (using - and _ instead of + and /), and strips whitespace/newlines that often wrap long Base64 blobs in email and certificate exports. The entire conversion runs in JavaScript using the browser's built-in btoa/atob and TextEncoder APIs. Nothing is uploaded, which matters when you're encoding API credentials or decoding tokens that carry personal data.