What is JWT Debugger & Inspector?
Ultitools JWT Debugger & Inspector decodes JSON Web Tokens locally in your browser, formats headers and payloads, analyzes expiration timestamps, and verifies HMAC SHA signatures with 100% privacy.
How to Use JWT Debugger & Inspector in 3 Simple Steps
No software installation, registration, or cloud file upload required.
Paste JWT Token
Paste your dot-separated encoded token into the input area.
Inspect Claims
View color-coded decoded Header and Payload JSON alongside live expiration badges.
Verify Signature
Optionally input your HMAC secret to verify cryptographic signature validity.
Technical Specifications & Quality Architecture
Machine-readable specifications verified under our Studio Master Quality Standard.
| Specification Property | Engine Configuration / Standard |
|---|---|
| Encoding Format | Base64URL UTF-8 |
| Crypto Engine | W3C Web Crypto API (SubtleCrypto) |
| Signature Algorithms | HMAC SHA-256 (HS256), HS384, HS512 |
| Privacy Rating | 100% Private (Zero server upload) |
Frequently Asked Questions
Clear, direct answers regarding privacy, performance, and features.
Yes. Unlike cloud JWT decoders, Ultitools executes 100% inside your browser memory. No tokens or secrets are ever sent across the network.
Supports HMAC SHA-256 (HS256), HS384, and HS512 verification via the browser native Web Crypto API.
Yes. It checks the exp claim against local system time and displays an active/expired badge with precise countdown.