Developer guides
Practical, in-depth references for the concepts behind our tools — from a full regex cheat sheet to how JSON Web Tokens work. Every guide links to a free, in-browser tool so you can try it immediately.
Encoders / Decoders
What is Base64 encoding? A complete guide
Base64 explained: what it is, how three bytes become four characters, why output is 33% larger, padding, URL-safe Base64, and why it is not encryption.
6 min read
How JSON Web Tokens (JWT) work
Understand JWTs: the header, payload, and signature, how signing and verification work, standard claims, HS256 vs RS256, and common security mistakes.
7 min read
URL encoding explained (percent-encoding)
What URL encoding is, why it is needed, reserved vs unreserved characters, encodeURIComponent vs encodeURI, %20 vs +, and how to build query strings correctly.
5 min read
Validators
Regex cheat sheet: every token, with examples
A complete regular expression cheat sheet: character classes, anchors, quantifiers, groups, and flags, each with a plain-English meaning and an example.
7 min read
How to validate JSON: rules, common errors, and fixes
Learn the rules of valid JSON, the most common errors like trailing commas and single quotes, and how to fix them — with examples you can test instantly.
6 min read
Cron expression examples and syntax guide
Understand cron syntax field by field, learn the special symbols, and copy ready-made cron expressions for common schedules — with a plain-English meaning for each.
5 min read
Converters
JSON vs YAML: differences, syntax, and when to use each
JSON vs YAML compared: syntax, readability, comments, data types, and the right format for configuration versus data interchange — with side-by-side examples.
6 min read
HEX vs RGB vs HSL: a guide to CSS color formats
Understand CSS color formats: how HEX, RGB, and HSL describe the same color, when to use each, adding transparency, and why CMYK is for print.
5 min read
Unix timestamps explained: epoch, UTC, and ISO 8601
What a Unix timestamp is, the epoch, seconds vs milliseconds, why timestamps are always UTC, ISO 8601, and the Year 2038 problem — with examples.
5 min read
Generators
UUIDs explained: v4, v7, and ULID
What a UUID is, how version 4 and version 7 differ, why v7 and ULID sort by time, collision odds, and when to use a UUID over an auto-increment ID.
5 min read
Hashing vs encryption vs encoding: what's the difference?
Hashing, encryption, and encoding are constantly confused. Learn what each one does, whether it is reversible, when to use it, and why passwords need special hashing.
6 min read