GOAT LabDevToolbox: 15 offline developer utilities, no login
DevToolbox is a free, fully client-side collection of 15 everyday developer utilities — formatters, encoders, generators, converters, and cheat sheets — that run entirely in your browser. Nothing you paste is ever uploaded.
- Free
- No sign-up
- Works offline
What is DevToolbox?
DevToolbox is a single-page web app bundling 15 common developer tools: a JSON formatter and validator, a JWT decoder, a URL encoder, a SHA hash generator, UUID and strong-password generators, a Lorem Ipsum generator, a live regex tester, a cron-expression explainer, Unix-timestamp and color converters, a text-case and number-base converter, and HTTP-status and MIME-type cheat sheets. Every tool computes locally with no server, no account, and no network request.
How does it work?
Each tool runs as pure client-side JavaScript using built-in browser APIs: native JSON parsing, the Web Crypto API for SHA hashes, crypto.getRandomValues for UUIDs and passwords, and native RegExp for the regex tester. Because all processing happens inside your browser tab, sensitive input such as tokens, payloads, and secrets never leaves your device.
When should I use it?
Use DevToolbox when you need to quickly format or validate JSON, inspect a JWT, hash a string, generate UUIDs or passwords, test a regular expression, understand a cron schedule, convert a Unix timestamp or a color, or look up an HTTP status code or MIME type — without installing anything or trusting a third-party server with your data.
At a glance
| Tools | 15 (formatters, encoders, generators, converters, cheat sheets) |
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| Processing | 100% client-side — no server, no upload |
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| Hashes | SHA-1 / SHA-256 / SHA-384 / SHA-512 (Web Crypto) |
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| Generators | UUID v4, strong password, Lorem Ipsum |
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| Converters | Unix time, color (HEX/RGB/HSL), number base, text case |
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| Cheat sheets | HTTP status codes, MIME types |
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| Account | None — free, no sign-up, works offline |
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| Languages | en, ja, es, zh, de |
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Frequently asked questions
Is my input sent to a server?
No. Every DevToolbox tool runs entirely in your browser using client-side JavaScript. Nothing you paste — JSON, tokens, or passwords — is ever uploaded or logged.
Which tools are included?
Fifteen tools: JSON formatter, JWT decoder, URL encoder, SHA hash, UUID generator, password generator, Lorem Ipsum, regex tester, cron explainer, Unix-time converter, color converter, case converter, number-base converter, plus HTTP-status and MIME-type cheat sheets.
Does the JWT decoder verify signatures?
No. It decodes and displays the header and payload for inspection only; it does not verify the signature, so never paste production secrets expecting validation.
Which hash algorithms are supported?
SHA-1, SHA-256, SHA-384 and SHA-512, computed with the browser's Web Crypto API. MD5 is intentionally omitted because it is cryptographically broken.
Do I need an account or installation?
No. DevToolbox is free, requires no sign-up and no install, works offline once loaded, and is available in English, Japanese, Spanish, Chinese and German.