Verify HS*/RS*/ES* JWT signatures with a pasted secret, PEM public key, or JWK — complements decode-only JWT Decoder.
- Free
- No signup
- Fast
- Privacy-friendly
What next?
Keep going with JWT Signature Verifier
Finish this check in the browser, then pick the path that matches how you work — another related tool, REST for apps, or MCP for agents.
- 1. Related check
After this result, run Secret leak scanner for the next signal.
Secret leak scanner - 2. Automate with API
Same job from your server with
Create free accountX-Api-Key. Free tier includes 500 credits/month. - 3. Hand off to an agent
Connect Cursor or Claude to ToolYour MCP — plan → run → verify.
MCP setup
What is JWT Signature Verifier?
Decode alone is not auth. JWT Signature Verifier checks HS* with a secret or RS*/ES* with a public key/JWK. Use <a href="/security-tools/jwt-decoder">JWT Decoder</a> for claims-only inspection and <a href="/security-tools/secret-leak-scanner">Secret Leak Scanner</a> if tokens appeared in logs. REST/MCP: /api/v1/security-apis/jwt-signature-verifier.
What are common questions about JWT Signature Verifier?
What does JWT Signature Verifier do?
Verify HS*/RS*/ES* JWT signatures with a pasted secret, PEM public key, or JWK — complements decode-only JWT Decoder.
Is this available via API and MCP?
Yes. Same route under /api/v1/security-apis/{slug} with one ToolYour API key.
What are the key features of JWT Signature Verifier?
Free browser access
Use JWT Signature Verifier without subscription or registration.
Cross-device support
Runs on desktop, tablet, and mobile browsers.
Privacy-focused
Inputs are processed to produce output and not kept longer than needed.
How do you use JWT Signature Verifier?
Open the tool
JWT Signature Verifier loads instantly — no signup required.
Provide input
Paste, type, or upload the input the tool expects.
Copy or download
Use the result in your workflow — outputs are yours to keep.
Auth helpers cluster
Free · API · MCPToolYour platform
Use JWT Signature Verifier three ways
The free JWT Signature Verifier on this page works in your browser. The same workflow is available via REST API for apps and via the remote MCP server for Cursor, Claude, and other agents — one API key, one plan, one quota. This tool is part of the security-apis module under Security Tools.
- 1Create a free accountGet an API key for REST and MCP — 500 credits/month on the free tier.
- 2Connect or callPaste the MCP URL into Cursor/Claude, or call REST with
X-Api-Key. - 3Same key & creditsBrowser smoke-checks stay free; API-backed runs share one monthly credit quota.
- Free in browserUse JWT Signature Verifier here — no account required.
- REST APICall from your server with
X-Api-Key. - Remote MCP serverSame job from Cursor or Claude via the ToolYour remote MCP server — one API key with REST.
Which secrets & auth tools sit in this cluster?
Where does this job fit on ToolYour?
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Which toolkits include JWT Signature Verifier?
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