Base64 Encoder
Encode and decode Base64 in the browser.
LocalYour data is processed locally in your browser and is not uploaded to Alphzen.
Paste text to encode or decode.
How to use
- Paste text to encode, or Base64 to decode.
- Turn on URL-safe if you need the Base64url alphabet used in JWTs and query strings.
- Select Encode or Decode.
- Copy or download the result.
Features
- UTF-8 encode/decode — Unicode is not passed through btoa() raw, which would break.
- Optional URL-safe output (RFC 4648 §5) without padding.
- Whitespace in encoded input is ignored when decoding.
- Clear errors for truncated or illegal Base64.
- Runs locally in your browser.
Examples
Ada Lovelace
QWRhIExvdmVsYWNl
FAQ
Is Base64 encryption?
No. Base64 is an encoding. Anyone can decode it. Do not use it to hide secrets.
Why does Unicode break in some Base64 tools?
btoa() operates on bytes as Latin-1 characters. Alphzen encodes the UTF-8 bytes of your text first, then Base64-encodes those bytes.
What is URL-safe Base64?
It uses - and _ instead of + and /, and usually omits padding. JWTs use this alphabet. Decoding accepts both standard and URL-safe input.
Related guides
Related tools
About this tool
Base64 turns binary or UTF-8 text into ASCII so it can travel through systems that expect printable characters. Email attachments, data URLs, and JWT parts all use a variant of it.
Decoding is the inverse for valid input. Invalid characters, bad padding, or a truncated string are errors — this tool does not guess a nearby valid document.
If you are inspecting a JWT, decode the token with the JWT Decoder rather than splitting it by hand. Related: URL Encoder for percent-encoding.