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Developer tools

Developer tools that respect your data

The hub for the lookup utilities engineers reach for a dozen times a day — formatting JSON, decoding a token, testing a pattern, hashing a string. This page's job is to get you to the right one in a click, and to reassure you that pasting a production payload or auth token here is safe: nothing leaves the tab.

  • No uploads — files stay on your device
  • WebAssembly fast
  • Works offline
  • 100% free, no sign-up

11 tools in Developer tools

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JSON Formatter

Format, minify, sort keys, and validate JSON instantly.

Base64

Encode text or files to Base64, decode safely.

URL Encoder

Percent-encode, decode, and parse query strings.

Hash Generator

Generate SHA-256, SHA-512, SHA-1, and SHA-384 hashes.

ScratchpadNew

Local snippet store for JSON, regex, JWT samples. IndexedDB-backed.

JWT DecoderNew

Decode any JSON Web Token, inspect header, payload, expiry.

Regex TesterNew

Test JavaScript regex with live highlighting and replace mode.

UUID GeneratorNew

Generate v4 random or v7 time-ordered UUIDs. Bulk up to 1000. Copy as txt / json / csv.

CSS Gradient GeneratorNew

Build linear, radial, conic gradients visually. Copy CSS, Tailwind, or SVG. Curated palette presets.

Cron Expression BuilderNew

Build + validate cron schedules with a visual editor. Live human-readable description. Next-fire-time preview.

Mock Data GeneratorNew

Generate fake names, emails, phones, addresses, dates for testing. Export JSON, CSV, or SQL INSERT.

Go deeper · Learning Center

Developer utilities explained — JWTs, regex, cron and JSON

Start here: which developer tool for which job

The everyday lookup tools, by task. Paste production payloads and tokens without worry — nothing leaves the tab. Find the row, follow the link:

TaskToolNote
Format or validate JSONJSON FormatterNative parser; canonical key sort
Inspect a JWT's claimsJWT DecoderDecodes, never verifies — keep the key safe
Test a regular expressionRegex TesterJavaScript engine, what runs in the browser
Decode a cron scheduleCron BuilderExplains the day-of-week OR trap
Encode or decode Base64Base64Encoding, not encryption
Hash or checksum a stringSHA-256 HashA one-way fingerprint

Who this hub is for, and where to begin

Backend and frontend engineers debugging an API response, DevOps folks sanity-checking a schedule before it ships, QA writing test fixtures, and anyone who has ever hesitated before pasting a real token into a random web 'decoder' — this is the set to bookmark. Because every tool runs in your browser, an internal JSON payload, a live JWT, or a hashed secret never travels the way it would on an upload-based service.

New here? JSON Formatter and the JWT Decoder cover the two most common jobs; the Regex Tester and Cron Builder round out the daily kit. For the concepts behind them — how JWTs are structured, where regexes blow up, how cron's fields interact — the Developer Learning Center hub goes deep so this page doesn't have to.

Frequently asked questions

  • Why use this instead of an online JSON validator?

    Most online validators send your JSON to a server for parsing. SnapToolz uses your browser's native `JSON.parse` — orders of magnitude faster on big payloads, and the data never travels. Critical for production data, auth tokens, or anything you'd worry about pasting into a random web tool.

  • Can I decode production JWTs here?

    Yes — and you should. The decoder runs entirely client-side, so even production tokens (which often contain identifying claims like user IDs, email, organisation IDs) stay on your machine. Never paste a JWT into a tool that says 'we don't store your data' but operates server-side — the request is observable in logs, in transit, and in whatever caching the operator runs.

  • Why a browser-based developer toolset vs. a desktop app?

    Browser tools load in under a second, work on any device (including borrowed laptops and phones), and stay in sync with the version everyone else is using. The trade-off is they're less powerful for batch jobs over thousands of files. For everyday lookups — formatting JSON, decoding a JWT, hashing a string, encoding a URL — the browser path is faster end-to-end because there's no install. Install SnapToolz as a PWA to keep it one click away offline.

  • Are my files uploaded anywhere?

    No. Every SnapToolz tool runs entirely in your browser using JavaScript and WebAssembly. Files are read locally, processed in memory, and the result is offered as a download. There is no backend.

  • Is everything free?

    Yes — every tool in this category and on the entire site is free with no sign-up, no daily limit, and no watermark.

Learn more about SnapToolz