Base64 Encode / Decode

Encode and decode Base64 instantly in your browser. Includes automatic size-overhead calculation — handy for data URIs and API testing.

✅ 100% free, no signup, runs entirely in your browser

If something is broken or not displaying correctly, let us know via the contact form — we use the feedback to improve.

Other Tools

1

Paste input

Paste raw text to encode or Base64 string to decode.
2

Toggle direction

Click Encode/Decode to switch. Result is instant and size overhead is shown.
3

Pick URL-safe variant

For URLs or JWTs, pick URL-safe (no =, + → -, / → _).

Why does Base64 grow size by 33%?

3 bytes (24 bits) become 4 chars of 6 bits each — that is 4/3 ≈ 133% size. See our blog post.

Can I encode binary files?

Yes. Drag & drop a file to read as binary and encode. Usable as data: URL directly.

Is my data sent to the server?

No. Encoding/decoding happens entirely in your browser via FileReader / TextEncoder.

How are newlines handled?

Input newlines are preserved. An option to break output every 76 chars (legacy MIME) is available.