Some tools you use without ever quite learning the thing underneath. You paste a JWT into a decoder without knowing what the three segments mean; you tweak a regex until the tests pass without understanding the engine; you copy a cron line from Stack Overflow and hope. This hub closes those gaps — short, practical explainers of the primitives, each paired with a tool that lets you experiment safely.
Crucially, these tools run entirely in your tab. Pasting a production token or an internal config into a server-backed 'decoder' leaks it; doing the same here doesn't, because there's no server to leak to.
The auth and data primitives
Start with tokens and structure. JWTs explained covers what a JSON Web Token actually is — encoded, not encrypted — and the gotchas (alg:none, RS/HS confusion) that bite real apps; the JWT decoder lets you inspect one without ever pasting a signing secret. For data wrangling, the JSON formatter validates and canonicalises payloads, and Base64 and SHA-256 cover the encoding and hashing you reach for alongside them.
Pattern matching and scheduling
Two notations cause more confusion than any others. Regular expressions are a tiny language most people learn by trial and error — a practical regex primer gives you the model, and the regex tester shows matches live. Cron's five fields look simple and routinely surprise people — the visual guide to cron expressions decodes them, and the cron builder translates a schedule into plain English before you trust it in production.
Guides in this hub
Developer
A daily developer toolkit that never opens a tab to elsewhere.com
6 min read
Developer
JWT explained — anatomy, security pitfalls, and what to check in a token
11 min read
Developer
Regular expressions — a practical primer from beginner to advanced
12 min read
Developer
Cron expressions — the visual guide for engineers
10 min read
Tools to put it into practice
Format, minify, sort keys, and validate JSON instantly.
Decode any JSON Web Token, inspect header, payload, expiry.
Test JavaScript regex with live highlighting and replace mode.
Build + validate cron schedules with a visual editor. Live human-readable description. Next-fire-time preview.
Encode text or files to Base64, decode safely.
Generate SHA-256, SHA-512, SHA-1, and SHA-384 hashes.
Frequently asked questions
Is it safe to paste a production JWT into a decoder?
Into this one, yes — it parses the token entirely in your tab and never transmits it. Treat the token like a password regardless: a valid, unexpired one grants account access, so decode an expired copy when you can.
Why does my regex work in one tool but not another?
Regex engines differ — JavaScript, PCRE, RE2 and POSIX disagree on lookbehind, named groups and Unicode handling. Our tester uses the JavaScript engine, which is what runs in the browser and Node.
Are these tools usable offline?
Yes. SnapToolz is a PWA, so once loaded, the developer utilities keep working with no network — handy on a plane or an air-gapped machine.