Inputs stay local
Pasted text and selected files are processed by JavaScript in this tab and are not uploaded to any server.
Developer tools · Local processing
JWT Decoder
Decode a JWT header and payload locally—with a clear warning that decoding is not verification.
Decode locally
Inspect a JWT header and payload
Decoding a token does not verify its signature. Do not treat decoded claims as authentic unless a trusted system verifies the signature and expected issuer.
The practical guide
Inspect token claims without overstating trust.
Base64url segments are decoded into readable JSON, but no signature, issuer, audience, or expiry validation is performed.
Validate before relying on output
Malformed inputs produce readable errors. Review converted or decoded content before using it in a production workflow.
Browser memory matters
Very large inputs can consume significant memory. File-based tools apply safety limits and large CSV parsing uses a worker when available.
Privacy by architecture
Your files and tool inputs stay in your browser.
The selected files, inputs, settings, and outputs are processed in this page and are not uploaded to any server.
Questions, answered
Frequently asked questions
Is my input uploaded?
No. The tool logic runs locally after the website code has loaded, and the input is not uploaded to any server.
Is anything saved?
No. These utilities do not save tool input to browser storage; clearing or closing the page discards it.
Can I use sensitive production data?
Local processing reduces exposure, but you should still follow your organization’s policies and avoid pasting secrets where unnecessary.