Dev tools — free & private forever.
Generate UUIDs, QR codes, and convert JSON, CSV & YAML — right in your browser. Nothing uploaded, no account needed.
Browse all dev tools
Generate QR code
Create a QR code for a URL, text, Wi-Fi, or contact card, with custom colors and a logo.
Generate barcode
Make a UPC, EAN, or Code 128 barcode from a number or text, with check digits added, as PNG or SVG.
Pick a color
Pick a color and copy its HEX, RGB, and HSL values, or convert one format to the others.
Test click speed
Click as fast as you can for 5, 10, or 30 seconds and get your clicks per second.
Test reaction time
Click when the screen turns green and get your reaction time in milliseconds, averaged over five rounds.
Test keyboard
Press any key and see it register on a full on-screen keyboard, with key codes and rollover.
Test sound
Play test tones from 20 Hz to 20 kHz or white and pink noise on the left, right, or both speakers.
Test screen colors
Fill your screen with red, black, white, green, or blue, or run a ghosting test.
Test for dead pixels
Cycle your screen through solid colors and line patterns to find dead, stuck, and hot pixels.
Test speakers
Play a beep on the left speaker, the right speaker, then both, to check channels and wiring.
Test touch screen
Drag across a grid to find dead zones on a touch screen and check how many fingers register at once.
Convert timestamp
Convert Unix timestamps to human-readable dates and back, with local/UTC/ISO 8601 output.
Count down to a time
See how long until any time of day, with a live countdown to the second in your time zone.
Generate UUID
Generate random UUID v4 identifiers, in bulk, with hyphens/uppercase/braces formatting.
Format JSON
Format, validate, and minify JSON with your choice of indent. Errors show where the problem is. Nothing is uploaded.
Decode JWT
Decode a JWT to read its header, payload and expiry. Decode only, nothing is uploaded.
Compare text
Compare two texts and see every added and removed line. Ignore case or whitespace, nothing is uploaded.
Test regex
Test a regular expression and see every match and capture group highlighted. Nothing is uploaded.
Beautify & minify code
Beautify or minify JSON, JavaScript, HTML, CSS, and YAML. Choose your indent, nothing is uploaded.
Convert JSON, CSV & YAML
Convert JSON, CSV, and YAML in any direction — CSV and YAML convert through JSON automatically.
A small set of developer utilities that run in the browser: generate UUIDs, create QR codes, pick colors, convert Unix timestamps, and convert between JSON, CSV and YAML. Nothing you paste is sent to a server.
How to use these developer tools
- 1
Choose a utility
Pick the tool from the grid above: UUID generator, JSON, CSV and YAML converter, timestamp converter, QR code or color picker.
- 2
Paste your input
Paste the data or set the options. Results appear immediately in the browser.
- 3
Copy or download
Copy the output into your code or download it as a file.
Why use these dev tools
Data stays local
Paste JSON, IDs or timestamps without sending them to a third party.
No setup
No install, no extension and no account. Open a tab and use it.
Format conversion
Move data between JSON, CSV and YAML in one tool.
Quick generators
Generate up to 100 UUIDs at once, and QR codes, without writing a script.
Frequently asked questions
What is a UUID?
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A UUID (universally unique identifier) is a 128-bit value written as 36 characters, like 123e4567-e89b-12d3-a456-426614174000. It is designed so two systems can generate IDs independently without colliding. Version 4 UUIDs are random, and are the kind most apps use.
Are UUIDs really unique?
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Not by a hard guarantee, but a random version 4 UUID has 122 random bits, so the chance of two colliding is negligible for any realistic system.
What is a Unix timestamp?
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The number of seconds since 1 January 1970 UTC. The timestamp converter turns that number into a readable date and back.
Is anything I paste uploaded?
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No. The tools run in your browser, so pasted data is not sent to a server.
Can I convert JSON to CSV or YAML?
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Yes. The JSON, CSV and YAML converter converts between all three formats.