What does the Encoder/Decoder widget do?
It helps you encode and decode URLs, Base64 strings, and JWT tokens in the browser without sending data to a server—useful for API contract debugging, auth troubleshooting, and payload inspection.
Encoder/Decoder
Encode and decode URLs, Base64 strings, and JWT tokens in your browser for API debugging, auth inspection, and distributed-systems integrity checks—without uploading sensitive payloads.
How to use Encoder/Decoder
- Choose URL, Base64, or JWT mode.
- Paste your input and choose the available encode or decode action.
- Inspect the result before copying it into your application.
Example: Base64 encoding hello produces aGVsbG8=. URL encoding a space produces %20.
Before you use the result: Decoding a JWT reveals its contents; it does not verify the signature or prove that a token is trustworthy. Base64 is encoding, not encryption.
Common questions
Is my data sent to a backend?
No. Encoding, decoding, and JWT parsing run client-side in your browser, which makes the tool safer for sensitive tokens and request bodies during local debugging.
Can it decode JWT headers and payloads?
Yes. Paste a JWT to inspect its header and payload for quick validation while building or troubleshooting APIs. Signature verification still depends on your secret or public key outside this tool.
When should I use URL encoding versus Base64?
Use URL/percent encoding for query strings and path-safe values. Use Base64 when you need a text-safe representation of binary or structured data in headers, JSON fields, or transport layers that expect ASCII-safe content.
Is this a free online JWT decoder?
Yes. It is a free browser JWT decoder and Base64/URL encoder that keeps working data on your device instead of posting tokens to a remote service.
Who is this encoder/decoder for?
It is built for developers, QA engineers, and integrators who need a fast local tool while debugging OAuth tokens, webhook payloads, API gateways, and client/server encoding mismatches.