UUID Generator (v4)
Need an ID for a database row or test fixture? Press the button for a fresh version 4 (random) UUID made by the browser's standard function — correctly formatted, and new on every click.
Paste here
Result
Base64 · URL
Decode a JWT
The signature is not verified — that needs the key, and pretending otherwise is worse than not doing it. This only decodes the contents.
Hash
MD5 is not included. Browsers don't offer it, and it should not be used for anything new.
UUID · time
—
Passwords
Color conversion
- HEX
- —
- RGB
- —
- HSL
- —
Contrast ratio (WCAG)
This is how text looks in that pair
—
Color palettes
Page details
Tags to paste
Paste code
Result
Only comments and whitespace are removed. Names are left alone — renaming without scope knowledge silently breaks code, and it does not make the code unreadable anyway.
Paste HTML
The pasted code is never executed and never leaves your browser — it is only read.
Result
Units
—
Pyeong ↔ square meters
1 pyeong is 400/121 m² (about 3.3058 m²). Type in either box and the other updates.
Apartment exclusive area
Apartment sizes quoted in pyeong in Korea usually mean supply area (exclusive area plus stairs and hallways), so they're larger than the exclusive area converted.
Year · sexagenary cycle
Japanese era (wareki) ↔ Gregorian
Short forms like R1.5.1 or H31 work. In a year when the era changed, enter the full date to get a single answer.
Number to Korean words
Used when writing amounts on contracts and quotes — the number and the words together make tampering harder.
—
Korean name romanization
Follows the Revised Romanization of Korean. Sound changes inside a given name aren't reflected, as the standard requires. A passport's English name is hard to change, so if you already use a spelling, keep it.
Enter the name in Hangul.
Naming style
Internationalized domain
See the form a non-ASCII domain is actually registered as (xn--). Uses the browser's own standard conversion.
Regular expression
Result
After replacement
Original
Revised
What changed
YAML support covers the widely used subset — where anchors, tags, or multiple documents appear, this stops and says so rather than misreading them.
Result
Cron expression
Next runs
Computed in this browser's time zone. Server cron usually runs in UTC, so these times can differ from what your server will do.
About this tool
How to use it
- 1 Press Generate UUID.
- 2 A new UUID appears next to the button. Each press replaces it.
- 3 Select it and copy.
Good to know
- The page audit reads HTML you paste — use the Link checker to follow a link
- YAML support covers the widely used syntax only
- JWT decoding unpacks the contents; it does not verify the signature
Frequently asked questions
Can two UUIDs collide?
A v4 UUID has 122 random bits, so the odds of a repeat are negligible. This tool uses a cryptographic random source.
Is a GUID the same thing?
Yes, same format. Microsoft calls UUIDs GUIDs.
Can I make many at once?
One at a time — each press gives a new one.
Tools that pair well with this
-
Folder structure builder
Write a tree and download it as a ZIP of real folders and files. For scaffolding a project in one go.
-
Batch file renamer
Rename many files by rule, generate name lists, and make dummy files for testing.
-
Token & cost calculator
Estimate how many tokens your text is and what each model would cost. Your text never leaves the browser.