Base64 URL Safe Encoder
Encode text to URL-safe Base64 — replaces + with - and / with _ so output is safe in URLs and JWT tokens. Free, instant, client-side encoder.
🔒 100% Client-Side Processing
Your data is processed entirely in your browser and never transmitted to any server.
0 / 100M Limit
Common Use Cases
Building JWT segments
Produce the URL-safe Base64 encoding JWTs require when hand-crafting test tokens or debugging token assembly.
Encoding data into URLs
Embed state, filters, or small payloads in a query parameter without + and / characters breaking the link.
Naming files from binary data
Generate filesystem-safe identifiers from binary hashes where / would create unintended directories.
Frequently Asked Questions
- How does URL-safe Base64 differ from standard Base64?
- Two characters change: + becomes - and / becomes _, and the trailing = padding is dropped. This makes the output safe inside URLs, cookies, and file names without percent-encoding — it is the encoding JWTs use for all three segments.
- Can I decode a JWT segment with this?
- JWT header and payload segments are URL-safe Base64 exactly as produced here. To decode one, reverse the substitutions (- back to +, _ back to /), re-add padding to a multiple of 4, and run atob() — or use our JWT Decoder, which does it for you.
- Is my data private when I use this tool?
- Yes. This tool runs entirely in your browser using client-side JavaScript — nothing you type is transmitted to, logged by, or stored on any server. You can safely process confidential text, tokens, or code.