Guides, Tutorials & Tips

Learn regular expression syntax from the ground up — character classes, quantifiers, groups, flags, and lookaround — plus 6 ready-to-use patterns, catastrophic backtracking, and how to test regex live, free online.

Learn how JWTs are structured, what the header, payload, and signature actually do, why decoding is not the same as verifying, and how to safely inspect a JWT — free, instant, entirely client-side.

Learn what JSON is, how to read and write it correctly, the 6 data types, common syntax errors, and how to instantly format or minify any JSON online with a free formatter tool.

Learn how cryptographic hash functions work, why MD5 and SHA-1 are broken, the avalanche effect, hashing vs encryption vs encoding, and how to hash text or files free online.

Learn how Base64 encoding works, when to use it, the difference between Base64 and Base64URL, real-world use cases in JWTs, data URIs, and MIME email, and how to encode or decode anything free online.