Overview
What this tool does
Base64 is an encoding scheme that turns binary data (bytes) into ASCII text using 64 printable characters. It's how you fit images inline in CSS or HTML, how authentication tokens are wrapped for safe transport in HTTP headers, how email attachments are embedded, and how cryptographic keys are shared in config files. This tool encodes and decodes in both directions: text-to-base64, base64-to-text, file-to-base64, and base64-to-file. UTF-8 is handled correctly, so non-ASCII characters round-trip cleanly. A URL-safe variant (uses - and _ instead of + and /, with no padding) is supported for tokens and identifiers that need to live in URLs. Everything runs in your browser; no upload, no server, no signup.
How to
Use it in 3 steps
- Pick the operation: Encode (data -> base64) or Decode (base64 -> data).
- Pick the input source: Text (paste / type) or File (any file from your device).
- If your downstream system needs URL-safe base64, toggle the URL-safe checkbox.
- Paste the text (or pick the file), then click the encode / decode button.
- Copy the result to your clipboard, or download it as a file. Text output downloads as .txt; binary decoded output downloads as the original file format.
FAQ
Frequently asked questions
▶Is my data uploaded?
No. Encoding and decoding both happen in your browser. The text or file you input never reaches a server.
▶What's the difference between regular and URL-safe base64?
Standard base64 uses the characters A-Z, a-z, 0-9, +, /, and = for padding. URL-safe (RFC 4648 §5) swaps + for - and / for _, and drops the = padding. This makes the output safe to embed in URLs, JSON, and filenames without escaping.
▶Does it handle non-ASCII text correctly?
Yes. We use the browser's TextEncoder/TextDecoder for proper UTF-8 round-tripping. Emojis, accented characters, CJK text, RTL scripts all work.
▶What's the file-size limit?
Constrained by your browser's memory. Files up to ~100 MB encode quickly; multi-GB files may run out of memory or freeze the tab.
▶Why does my encoded output start with 'data:image/png;base64,...'?
That's a data URL, which is base64 with a MIME-type prefix. This tool produces pure base64 (no prefix). If you need a data URL for an <img src=> or CSS background, manually prefix the output with 'data:<mime-type>;base64,'.
▶Is base64 encryption?
No. Base64 is encoding, not encryption. Anyone can decode base64 back to the original. If you need to protect data, encrypt it before encoding.