Developer Guides
Short, practical explanations of the formats and tools developers use every day. Each guide links to a free tool on this site so you can try the examples as you read — in your browser, with nothing uploaded.
How JWT Signatures Work (HS256 vs RS256, Explained)
What the three parts of a JSON Web Token are, how the signature is computed, why decoding is not verifying, and the mistakes that lead to JWT vulnerabilities.
·Tool: JWT DecoderCron Syntax Cheatsheet: Fields, Operators and 25 Ready-Made Schedules
A practical reference to the five-field cron format, the special characters, common schedules you can copy, and the gotchas in crontab, GitHub Actions and Kubernetes.
·Tool: Cron Expression GeneratorFixing "Unexpected token" and Other JSON Parse Errors
What JSON.parse errors like "Unexpected token < in JSON", "Unexpected end of JSON input" and "Expected double-quoted property name" really mean, and how to fix each one.
·Tool: JSON Formatter & ValidatorBase64 Encoding Explained: How It Works and When to Use It
How Base64 turns bytes into text, why output is a third larger, what the = padding means, Base64 vs Base64URL, and how to handle Unicode correctly in JavaScript.
·Tool: Base64 Encoder / DecoderUUID Versions Explained: v1, v4, v5 and v7 — Which Should You Use?
How to read a UUID, what distinguishes each version, how likely a v4 collision really is, and why UUIDv7 is becoming the default for database primary keys.
·Tool: UUID GeneratorJavaScript Regex Cheatsheet: Syntax, Flags and Common Pitfalls
A compact reference to JavaScript regular expressions — character classes, quantifiers, groups, lookarounds, flags — plus practical patterns and the bugs that catch everyone.
·Tool: Regex TesterUnix Timestamps Explained: Seconds vs Milliseconds, Timezones and 2038
What a Unix (epoch) timestamp is, how to tell seconds from milliseconds, converting in JavaScript, Python and SQL, and the timezone and Year 2038 pitfalls.
·Tool: Unix Timestamp Converter