Catastrophic Backtracking: Spot and Fix ReDoS-Prone Regex
Learn why nested quantifiers cause catastrophic backtracking, how ReDoS attacks freeze servers, and concrete techniques to detect and rewrite vulnerable regex.
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All articles about security: 5 practical guides and tutorials from our free, privacy-first online tools.
JWT 'exp' Claim: Fixing Token Expired Errors
Fix JWT token expired errors caused by the exp claim — clock skew, timezone bugs, refresh failures, and leeway — with a fast browser-based decoder workflow.
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JWT Decode vs Verify: Decoding Doesn't Validate a Token
Decoding a JWT only reads its claims; verifying checks the signature. Learn the difference, why it causes auth bugs, and how to test both safely.
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JWT Tokens Explained: How They Work and How to Debug Them
Understand JSON Web Tokens: structure, claims, signing vs encryption, expiry, and signature verification — plus the security mistakes that cause auth bugs.
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How to Merge PDFs Without Uploading Them to a Server
Merge multiple PDF files securely in your browser with no uploads, no accounts, and no data ever leaving your device — completely private and free.
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