Standards, edge cases, and pitfalls worth knowing before you use a tool.
12 guides
Base64 turns bytes into ASCII text that anyone can reverse, since there is no key. See what it is for, the URL-safe variant, padding and the 4/3 size overhead.
Text has different byte counts in UTF-8, UTF-16, EUC-KR (CP949) and Shift_JIS (CP932). See the numbers and how to fit VARCHAR and fixed-length records.
GitHub Actions runs cron schedules in UTC by default and Kubernetes uses the controller's time zone. Learn the 5-field syntax, time zone fields and the OR rule.
Large integer IDs in JSON lose digits in JavaScript because numbers are IEEE 754 doubles, exact only up to 2^53 − 1. Keep them exact with string IDs or BigInt.
Trailing commas, single quotes, unquoted keys, comments, unclosed brackets, NaN and duplicate keys: why each one breaks JSON under RFC 8259 and how to fix it.
To open JSON in Excel, convert it to CSV with a UTF-8 BOM and RFC 4180 quoting. See how commas, quotes, line breaks and leading zeros are handled.
Decoding a JWT only reads Base64URL text and does not verify the signature. See the token structure, how to read exp, iat and nbf, and why alg none is rejected.
URLs allow only part of ASCII, so other characters are written as %XX bytes. See why UTF-8 and EUC-KR results differ and when to use encodeURIComponent.
MD5, SHA-1 and SHA-256 differ in digest length and collision resistance. See which one fits checksums and signatures, and why passwords need bcrypt or Argon2.
Ten regular expression patterns with tested examples, plus how catastrophic backtracking (ReDoS) happens with patterns like (a+)+ and how to rewrite them.
Unix time counts seconds since 1970 in UTC. Learn to tell seconds from milliseconds by digit count, handle time zones, and see what overflows in 2038.
UUID v4 is random, while UUID v7 and ULID begin with a timestamp and sort by creation time. Compare their layout, index locality and privacy trade-offs.