Developer Tools Hub

Tool input never leaves your browser. Every tool — cron parser, regex tester, JWT decoder, hash generator, and the rest — runs entirely in client-side JavaScript. No input is sent to any server, logged, or stored.

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Mostly. All tools run locally once the page is loaded. If you lose connectivity mid-session, every tool already on the page continues to work. Google Fonts, the js-yaml library (served from cdnjs), and Google Analytics require internet access — if fonts fail to load the page still functions with a system monospace fallback.

For guaranteed offline use, save the page to disk and open it locally.

What it does: Parses a standard 5-field Unix cron expression into plain English and calculates the next five scheduled run times from the current moment.

⚠ Results reflect standard Unix cron semantics. systemd timers, AWS EventBridge, Quartz Scheduler, and other platforms have their own variations. Always verify in your target environment before deploying.

What it does: Converts data between JSON, YAML, and CSV. Powered by js-yaml for YAML parsing and a lightweight CSV implementation for flat arrays.

⚠ CSV conversion assumes a flat structure (array of objects with scalar values). Nested objects or arrays will be stringified. Round-tripping through CSV may lose type information (numbers become strings).

What it does: Tests a regular expression against a sample string, highlights every match inline, and lists each capture group with its position and value.

⚠ Uses the JavaScript RegExp engine. Patterns from Python re, PCRE (PHP/Perl), or Go regexp may behave differently — especially around lookaheads, named groups, and backreferences.

What it does: Converts text to Base64 or decodes Base64 back to text. Unicode input is handled correctly via UTF-8 encoding before conversion.

⚠ Base64 is encoding, not encryption. Anyone who sees the encoded string can decode it instantly. Never use Base64 to conceal sensitive data.

What it does: Splits a JSON Web Token (header.payload.signature) into its three Base64URL-encoded parts and displays the header and payload as formatted JSON.

⚠ This tool does not verify the signature. A decoded token is not a validated token. Do not paste real production or session tokens — treat them as sensitive credentials.

What it does: Generates version-4 UUIDs using crypto.randomUUID() — the browser's cryptographically secure random number generator. You can generate 1 to 50 at a time.

⚠ V4 UUIDs are random and collision-resistant but they are not secret keys or passwords. Do not use a UUID as a secret, API token, or cryptographic key.

What it does: Converts between Unix timestamps (integer seconds since 1970-01-01T00:00:00 UTC), ISO 8601 date-time strings, and human-readable local time in your current timezone.

⚠ All output uses your browser's local timezone. The UTC offset is shown in the result. For timezone-critical work, confirm the offset matches your target environment.

What it does: Produces the SHA-256 or SHA-1 hex digest of any text you enter, using the browser's built-in crypto.subtle.digest() API.

⚠ Do not use these for passwords. SHA-256 is not a password hashing function — it is fast by design, which makes it trivial to brute-force. Use bcrypt, Argon2, or scrypt for password storage.

What it does: Takes a hex color code and converts it to its RGB and HSL equivalents with a live color swatch so you can see the actual color at a glance.

What it does: Applies percent-encoding (equivalent to JavaScript's encodeURIComponent) to a string, or decodes percent-encoded sequences back to plain text.

⚠ This tool encodes the entire input as a URI component. If you want to encode only the query-parameter values of a full URL, paste each value individually rather than the whole URL.