Generate RFC 4122 version 4 UUIDs (GUIDs) using cryptographically secure randomness, entirely in your browser.
A UUID (Universally Unique Identifier, also called GUID on Windows) is a 128-bit number used to uniquely identify data across systems without a central authority. Version 4 UUIDs are generated from random numbers.
Practically yes. A v4 UUID has 122 random bits, giving 2^122 ≈ 5.3 × 10^36 possibilities. The chance of a collision is negligible even after generating billions per second for millennia.
Tip: press Space or R to regenerate.
RFC 4122 compliant, cryptographically random, entirely client-side.
Uses crypto.randomUUID or crypto.getRandomValues — the browser's cryptographically secure random number generator, same as banks and password managers.
Produces true version 4 UUIDs with the correct version bits (4xxx) and variant bits (10xx). Guaranteed unique for all practical purposes (2^122 possibilities).
Available in 25 languages with automatic browser detection. RTL support for Arabic, Persian and Urdu.
Generate 1 to 10 UUIDs at once. Copy individual UUIDs, copy all at once, or download as a.txt file.
Standard lowercase, uppercase, without hyphens, or with braces {} — for whatever system consumes them (SQL Server,.NET, Postgres, etc.).
All UUIDs are generated entirely in your browser. Nothing is sent to any server, no logging, no telemetry.
RFC 4122 v4 UUIDs from your browser's CSPRNG, single or batch.
Generate a single UUID, a small batch (10 / 100), or up to 10,000 at once for seeding test data. Larger batches stream into the textarea so the page doesn't lock up.
Modern browsers expose crypto.randomUUID, which produces an RFC 4122 v4 UUID using the same hardware-backed randomness as crypto.getRandomValues. We use it directly — no third-party library, no quality compromise.
Choose lower-case (default), upper-case, with/without hyphens, or with curly braces (Microsoft GUID format). The transformation is a string replace; the underlying randomness is the same.
One-click copy puts a single UUID on your clipboard. For batches, download as a .csv with one UUID per line — useful for seeding a database or generating test fixtures.
Different ID schemes have different tradeoffs.
v4 is fully random, so it spreads inserts across B-tree pages instead of hot-spotting the latest page. Good for low-to-medium-write tables; for high-write tables consider UUID v7 (timestamp-prefixed) for index locality.
Generate a fresh UUID per request to correlate logs across services. v4 is plenty unique — collision probability is mathematically negligible.
Need 1,000 unique IDs for a test fixture? Generate a batch, paste into your seeder, done. Faster than calling a database UUID function 1,000 times.
When you sign a JWT, the jti (JWT ID) claim should be unique per token. v4 is the standard choice — paste a fresh one into your token signing code.
If a UUID generator pulls randomness from a server, two failure modes appear: the server can leak the IDs you generated (linking them to your IP), or — worse — produce predictable IDs if its RNG is weak. iKit uses your browser's hardware-backed CSPRNG directly, so neither is possible.
crypto.randomUUID is non-deterministic and standardised.
Deep-dive tutorials and tool comparisons from the iKit blog.
A UUID (Universally Unique Identifier, also called GUID on Windows) is a 128-bit number used to uniquely identify data across systems without a central authority. Version 4 UUIDs are generated from random numbers.
Practically yes. A v4 UUID has 122 random bits, giving 2^122 ≈ 5.3 × 10^36 possibilities. The chance of a collision is negligible even after generating billions per second for millennia.
No. Generation happens entirely in your browser via JavaScript's Web Crypto API. No network request is made when you generate a UUID. Verify it yourself in your browser's Network tab.
They are the same thing. GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit identifier defined by RFC 4122. This tool produces identifiers interoperable with both.
Yes, UUIDs are commonly used as primary keys in distributed systems. However v4 is random — if you need sortable/time-ordered IDs (ULID, v7, Snowflake), use a different scheme to avoid B-tree index fragmentation.