Premium Developer Toolkit // 8 tools · 100% local
All Toolkits
8 tools · runs 100% in your browser · zero servers

The Developer Toolkit
that lives in a single HTML file.

Eight polished utilities — JSON formatter, Base64, JWT decoder, regex tester, hash generator, UUID generator, color converter, and timestamp converter. No tracking, no uploads. Just open and ship.

{ }JSON Formatter & Validator

Paste any JSON to pretty-print, minify, validate, and explore it as an interactive tree. Parse errors are reported with line and column.

Input

Output

idle
Formatted JSON will appear here.

b64Base64 Encoder / Decoder

Encode UTF-8 text to Base64 and decode Base64 back to text. Fully Unicode-safe — handles emoji, CJK, and accented characters correctly.

Text input

Result

Output appears here.

JWTJWT Decoder

Decode a JSON Web Token to inspect its header, payload, and signature. Expiry is shown in human-readable form with a warning when expired. Signature is not verified.

Paste JWT

waiting

/.*/Regex Tester

Test a JavaScript regular expression against a string. Matches are highlighted inline, and each match is listed with its index, groups, and captured values.

/ /
idle
Try \b\w{4}\b with flags gi

Highlighted matches

Run a test to see highlighted matches.

Match list

No matches yet.

#Hash Generator

Generate cryptographic hashes with the native Web Crypto API. Supports SHA-1, SHA-256, SHA-384, and SHA-512, plus an MD5 implementation in pure JavaScript. Everything is computed locally.

UTF-8 encoded · Web Crypto API

Digests

MD5 —
SHA-1 —
SHA-256 —
SHA-384 —
SHA-512 —

idUUID Generator

Generate cryptographically secure version-4 UUIDs using crypto.randomUUID(). Batch generate, uppercase, and copy with one click.

idle

Generated UUIDs

0
Generated UUIDs will appear here.

◆Color Converter

Convert between HEX, RGB, HSL, HSV, and CMYK. Type any value and the format is auto-detected; every representation updates instantly with a live preview.

Supports #hex, rgb(), hsl(), hsv(), cmyk(), and bare r,g,b.
Quick picks:
#00FF88

Conversions

HEX #00ff88
RGB rgb(0, 255, 136)
HSL hsl(152, 100%, 50%)
HSV hsv(152, 100%, 100%)
CMYK cmyk(100%, 0%, 47%, 0%)
Red
0
Green
255
Blue
136

⌚Timestamp Converter

Convert Unix timestamps to human-readable dates and back. Supports seconds and milliseconds, multiple output formats, and a live clock of the current time.

Current Unix time — —

Unix → Date

Converted date appears here.

Date → Unix

Unix timestamp appears here.

Frequently asked questions

Everything you need to know about the Premium Developer Toolkit, its privacy model, and supported algorithms.

No. Every tool in the Premium Developer Toolkit runs entirely in your browser using client-side JavaScript. Your JSON, tokens, text, and other inputs never leave your device, which makes the toolkit safe to use with sensitive data like JWTs and API credentials. There are no analytics on input content and no backend calls.
The Hash Generator supports SHA-1, SHA-256, SHA-384, and SHA-512 through the native Web Crypto API, plus an MD5 implementation written in pure JavaScript. Note that MD5 and SHA-1 are cryptographically broken and should only be used for checksums, file fingerprints, or legacy compatibility — never for password storage or security-sensitive signatures.
UUIDs are generated as version 4 (random) UUIDs using the browser's cryptographically secure crypto.randomUUID() API when available, with a fallback to crypto.getRandomValues() for older browsers. Both sources use the operating system's CSPRNG, so the resulting UUIDs are unpredictable and suitable for use as database primary keys, request IDs, or distributed identifiers.
No. The JWT decoder only base64url-decodes and displays the header, payload, and signature. It does not verify the cryptographic signature because verification requires the signing secret (for HMAC) or public key (for RSA/ECDSA). Always validate tokens on your server using a trusted, audited library such as jsonwebtoken (Node.js), jose, or the official SDK for your framework.
Yes. After the page has loaded once, all tools work completely offline because every line of logic is embedded in this single HTML file. Use the "Download HTML" button in the header to save a local copy, then open it directly in any modern browser — no internet connection, server, or installation required.
The toolkit works in any modern browser that supports the Web Crypto API, ES2020 JavaScript, and CSS custom properties. This includes current versions of Chrome, Edge, Firefox, Safari, and Brave on both desktop and mobile. If your browser is more than a few years old, some tools (particularly the hash generator and UUID generator) may fall back to alternative implementations or be unavailable.