buncha/code & dev/b64

Base64 Encoder / Decoder

Stays on this device. UTF-8-safe Base64 — handles emoji, CJK, accented Latin properly (older online tools using naked btoa break on these). URL-safe variant for JWT-style tokens. Nothing you paste leaves your browser.

URL-safe variant (-, _ instead of +, /; no padding)

About Base64. Base64 represents binary data as ASCII — 64 characters (A-Z, a-z, 0-9, plus + and /), with = as padding. Used for embedding images in CSS data URIs, encoding email attachments (MIME), passing tokens through URL-unsafe transports, and a few hundred other places. Encoding inflates size by ~33% (3 bytes → 4 chars) — it's NOT compression and NOT encryption; anyone can decode it trivially. The URL- safe variant (the one JWT tokens use) swaps + → -, / → _, and drops trailing padding so the result is safe to put in URL paths and query strings without further escaping.

Pairs well with

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About Base64 Encoder / Decoder

Encode any text to Base64 or decode a Base64 string back to the original. Handles UTF-8 properly, supports URL-safe Base64, runs entirely in your browser.

Base64 is a way to represent binary data using only ASCII characters — used for embedding images in CSS / HTML data URIs, encoding email attachments (MIME), passing tokens through URL-unsafe transports, and hundreds of other places. The 'URL-safe' variant (`-` and `_` instead of `+` and `/`) is what JWT tokens use.

This tool uses the browser's native `btoa` / `atob` (with a TextEncoder hop for proper UTF-8 handling — `btoa` alone fails on emoji and non-Latin text). No server round-trip. Encoding inflates the size by ~33% (3 bytes → 4 chars).

Common questions

Why does my emoji break with btoa?

Native btoa only handles Latin-1 (codepoints 0-255). For UTF-8 strings (emoji, CJK, Cyrillic), you need to encode to bytes first. This tool does that automatically.

Is Base64 encryption?

No — it's encoding, not encryption. Anyone can decode Base64 trivially. Use it for transport, not for security.

Like every tool on Buncha, this one runs entirely in your browser. There's no upload, no log, no record of what you've pasted or generated. Close the tab and the data is gone.

↳ Have feedback or found a bug? hello@buncha.tools