e30fed36-c627-4129-9c9b-458c418d0174 Generate Random UUIDs
Click generate and the tool produces one or up to one thousand RFC 4122 version 4 UUIDs in a batch, each 128 bits of cryptographic randomness rendered as a hyphenated lowercase hex string (8-4-4-4-12). The browser's native crypto.randomUUID() is the source of entropy, so the output is indistinguishable from random and safe to use as an identifier where uniqueness matters.
Use this to seed a database with unique primary keys, mint request or trace IDs for debugging, produce correlation tokens for distributed tracing, generate unique asset names for an upload pipeline, create stable IDs for a spreadsheet or CSV export, or populate a fixture with a fresh batch of random IDs for test runs. For monotonic time-ordered IDs inside a database, UUID v7 or ULID is usually preferable — v4 is the right default when order does not matter.
Options control the surface of the output: toggle uppercase for the A-F hex digits, strip the dashes to get a 32-character compact form, and choose the batch size from 1 up to 1000 for bulk seeding. Each UUID has a one-click copy, and a copy-all button puts the entire batch on the clipboard as newline-separated values ready to paste into a shell, a file, or a SQL INSERT.
Generation runs entirely in your browser — no server is involved, so you can trust the values are only ever known to you.
About this tool
UUID (Universally Unique Identifier) v4 generates 128-bit identifiers using cryptographic randomness. They're virtually guaranteed to be unique and are widely used as database primary keys, session tokens, and correlation IDs.
- Cryptographically random UUID v4
- Bulk generation (up to 1000)
- Uppercase and no-dashes options
- Copy individual or all UUIDs
100% client-side. Your inputs never leave your browser. Ads via AdSense (consent required).
Frequently asked questions
How do I generate a UUID?
Click generate and the tool produces a new RFC 4122 version 4 UUID instantly using the browser's crypto.randomUUID() — 122 bits of cryptographic randomness rendered as a hyphenated lowercase hex string in canonical 8-4-4-4-12 form. A bulk mode generates up to 1000 UUIDs at once, useful for seeding test data or fixtures. Options let you toggle uppercase or strip the dashes for the 32-character compact form.
Is the UUID generator free?
Yes, completely free, no signup, no limit on how many UUIDs you generate. JSONCraft is free across every tool including this one. People run bulk generation all day for test fixtures, migration scripts and seed data; nothing is rate-limited because nothing touches a server.
Does the UUID generator upload anything?
No. UUID generation is a pure local operation using the browser's crypto.randomUUID(). Nothing is transmitted, nothing is logged, and there is no server-side component. Since UUIDs are frequently used as primary keys, tokens, or correlation IDs that end up in databases and logs, keeping generation client-side means the values never transit a third party.
When should I use UUID v4 vs something like v7 or ULID?
v4 (what this tool generates) is the safe default for most cases — no information leakage, fully random, globally unique with overwhelming probability. If you need monotonic, timestamp-ordered IDs for database primary keys (better insert locality on Postgres/MySQL B-trees), UUID v7 or ULID are preferable — they sort chronologically so inserts stay near the index tail. For ordering-insensitive workloads, stick with v4.
What's the collision probability of UUID v4?
Astronomically small. A UUID v4 has 122 random bits, giving 2^122 (~5.3 × 10^36) possible values. To have a 50% chance of one collision you'd need to generate around 2^61 UUIDs — more than 2 billion per second for 36 years. For practical systems, treat collisions as impossible; no retry or uniqueness check is needed in normal workloads.