JWT Debugger & Token Comparator
Decode, compare character-by-character, verify signatures, check expiry & security audit. 100% client-side.
Token Comparator & JWT Security Analyzer
Compare, decode, and analyze authentication tokens entirely in your browser. Perfect for debugging JWT tokens, API keys, OAuth tokens, Bearer tokens, and session tokens.
🔒 Privacy First
All processing happens locally. No tokens are stored, logged, or transmitted. 100% client-side.
Token Comparator
Compare two tokens character-by-character. Paste one token to decode and analyze; paste two and click Compare for diff.
⚠ Never paste production secrets into unknown tools
UnblockDevs tools run fully client-side; your tokens never leave your device. Still, only use this in environments you trust.
Common Use Cases
JWT verification
Compare and decode JWTs, check claims and expiration.
API key validation
Verify keys match between environments.
Auth token debugging
Session, OAuth, Bearer tokens – decode and compare.
Hash comparison
Compare hashes and checksums character-by-character.
What Is a Token Comparator?
A token comparator lets you paste two tokens — JWTs, API keys, OAuth tokens, webhook secrets, or any text-based credential — side by side and see exactly where they differ. Every character is compared individually and highlighted: green for matches, red for mismatches. This makes it effortless to spot a single wrong character in a 500-character JWT or detect which environment has a different signing secret.
Beyond the character diff, the JWT Debugger & Token Comparator auto-detects the token type (JWT, API key, UUID, Base64) and unlocks the right analysis: JWT tokens get full header/payload decode, claim inspection (exp, iat, iss), expiry check, entropy analysis, and a security audit. Everything runs 100% in your browser — your tokens never leave your device.
Compare Tokens in Seconds
Paste Token A & B
Enter your first token in the left field and your second token in the right field. The tool auto-detects the type of each.
See the Character Diff
Click Compare for an instant character-by-character visual diff with match percentage and mismatch count.
Check JWT Claims & Expiry
For JWTs, inspect the decoded header and payload, check expiration datetime, and see remaining or elapsed lifetime.
Run Security Audit
Detect alg:none, weak or missing secrets, absent exp/nbf claims, iss mismatches, and long-lived tokens in one click.
When Developers Compare Tokens
Debug Auth Failures Between Envs
Paste the working dev token and the failing production token to pinpoint the exact claim or character that differs.
Detect JWT Tampering
Compare an original JWT with a suspicious one to spot header or payload modifications that could indicate a tampering attempt.
Compare API Key Permissions
Verify that two API keys are identical across environments — or find the one character that was miscopied.
Verify Webhook Secrets Match
Confirm the webhook secret configured on the provider matches the one stored in your environment variables.
Token Rotation Testing
After rotating a signing key, compare old and new tokens to verify the new ones have the expected claims and structure.
Diff Bearer vs API Key
Compare a Bearer JWT against an opaque API key to understand format differences and choose the right auth scheme for your API.
JWT Security Vulnerabilities to Check
The built-in security audit flags the most dangerous JWT misconfigurations before they reach production. Run any JWT through the tool to get an instant security report.
| Vulnerability | What it means | Risk |
|---|---|---|
| alg: none | Algorithm set to "none" — signature is stripped and any payload is accepted | Critical |
| Weak secret | Short or common signing secret that can be brute-forced offline | High |
| Missing exp / nbf | Token has no expiration or "not before" claim — valid forever | High |
| iss mismatch | Issuer claim does not match the expected value for your service | Medium |
| Long-lived token | exp is set far in the future — large window for replay attacks | Medium |
Frequently Asked Questions
1How do I decode a JWT token?
2How do I check if a JWT token is expired?
exp claim (a Unix timestamp) and shows the exact expiration datetime, whether the token is currently valid, and how much lifetime remains or how long ago it expired.3What is the JWT "none" algorithm vulnerability?
alg:none attack lets a malicious actor remove the JWT signature so a vulnerable server accepts any payload without verification. The security audit in Token Comparator detects this automatically alongside other misconfigurations.4How do I compare tokens across environments?
5What is token entropy and why does it matter?
6Are my tokens stored or sent to a server?
7How do I reduce token count in prompts?
8What is the context window limit for LLMs?
9How does tokenization differ between GPT-4 and Claude?
10How do I estimate AI API call cost?
11What is BPE tokenization?
12How do I manage token limits in a long conversation?
Developer Guides
Feedback for token_comparator
Tell us what's working, what's broken, or what you wish we built next — it directly shapes our roadmap.
Good feedback is gold — a rough edge you hit today could be smoother for everyone tomorrow.
- Feature ideas often jump the queue when lots of you ask.
- Bug reports with steps get fixed faster — paste URLs or examples if you can.
- Name and email are optional; we won't use them for anything except replying if needed.
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