Inspect JWT headers and payload data in the browser.
JWT Decoder uses a JWT string to decode the Base64URL header and payload sections of a JWT without verifying its signature. In the browser, JWT Decoder uses a JWT string to decode the Base64URL header and payload sections of a JWT without verifying its signature. JWT Decoder then places the decoded jwt header and payload in the result panel.
For JWT Decoder, the first two JWT segments are treated as Base64URL-encoded JSON after replacing - and _ with Base64 characters. For JWT Decoder, the code parses both segments as JSON and does not use the signature segment.
JWT Decoder example input: JWT = eyJhbGciOiJub25lIiwidHlwIjoiSldUIn0.eyJzdWIiOiIxMjMifQ. JWT Decoder expected result: The sample displays header {"alg":"none","typ":"JWT"} and payload {"sub":"123"}; the empty signature is not verified. To verify JWT Decoder, reproduce its worked example and compare the displayed or downloaded decoded jwt header and payload with the stated expected result. When JWT Decoder returns a file, open the download and inspect every affected page or image.
JWT Decoder requires exactly three dot-separated segments and reports an error when the first two segments cannot be decoded and parsed as JSON.
For JWT Decoder, decoded claims are untrusted until a separate system verifies the JWT signature, algorithm, issuer, audience, expiry, and application rules.
JWT Decoder runs the jwt decoder operation in the current browser session. JWT Decoder reads and processes the supplied values in the current browser and does not submit them to an application endpoint. Browser extensions, device security and any manual sharing or download from JWT Decoder remain outside the tool’s control.
For JWT Decoder, no explicit text-length, file-size or numeric-range cap is enforced by this operation code. With JWT Decoder, empty input can produce an empty result or a validation message; With JWT Decoder, characters, formats or browser features outside those handled by the operation may change or prevent the result.
After using JWT Decoder, you may also find these tools useful: base64-encoder-decoder, json-formatter, regex-tester.
Continue the workflow
JWT Decoder is part of the Developer Tools section. Use the nearby pages below when the same job needs checking, cleanup, conversion, formatting, or a different output before you finish.
