UUID / GUID Generator
Generate random UUIDs (Universally Unique Identifiers) instantly.
Why Use UUID / GUID Generator?
Auto-incrementing integer primary keys work fine for a single database, but the moment you add a second service, offline clients, or shard across regions, you need identifiers that can be created independently without coordination. UUIDs solve that: any service can mint an ID and trust it's globally unique. Generating them in-browser (instead of calling a backend endpoint) also lets you seed test fixtures, write migrations, and populate sample data without touching a server or risking accidentally using low-entropy random sources.
How to Use UUID / GUID Generator
- Click the 'Generate' button to create a new random UUID (Version 4).
- Use the bulk generate option to create multiple UUIDs at once — specify the number you need.
- Copy individual UUIDs or the entire batch to your clipboard with one click.
Worked Examples
A single v4 UUID for a new record
Generate 1 × v4
3f7c4e8a-9b1d-4f2a-8e6c-5d0fa12b3c47
The '4' in the third segment marks this as version 4 (random).
Bulk generation for test fixtures
Generate 5 × v4
550e8400-e29b-41d4-a716-446655440000 6ba7b810-9dad-41d1-80b4-00c04fd430c8 7d793037-a076-4f3c-9423-1b4b3f5d9a28 b7e3fc4c-4e75-4a6a-bc2a-1f0b9e4c4d12 a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11
Paste into a seed script or INSERT statement.
UUID as a JSON key
{ "id": "<uuid>", "created": "2026-04-15" }{ "id": "c8e5d420-5d8e-4a31-9d8e-74f0f4c2e11a", "created": "2026-04-15" }Useful when prototyping API responses.
About UUID / GUID Generator
A UUID (Universally Unique Identifier) is a 128-bit identifier presented as 32 hexadecimal digits in the format 8-4-4-4-12, used to uniquely identify resources in distributed systems without a central authority. The UUID Generator creates cryptographically random Version 4 UUIDs that are safe to use as database primary keys, session tokens, file identifiers, and tracking IDs. UUIDs are 128-bit identifiers presented as 32 hexadecimal digits in the format 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). Version 4 UUIDs are generated using random or pseudo-random numbers, making collisions virtually impossible — the probability of generating two identical UUIDs is astronomically low. Our generator uses the browser's built-in crypto.getRandomValues() for true cryptographic randomness. Batch generation lets you create multiple UUIDs at once for database seeding, test data, or configuration files.
Troubleshooting & Common Issues
"Math.random()"-style UUIDs aren't acceptable for my use case
This tool uses the browser's crypto.getRandomValues(), which draws from the OS-level cryptographic RNG — the same source used for TLS session keys. It's appropriate for session tokens, API keys, and anything requiring strong randomness. If you still need certified randomness (FIPS 140-3), generate UUIDs on your server with a validated RNG.
My database is showing fragmentation from random UUIDs
v4 UUIDs are random, so inserts land in random locations in a B-tree index, causing page splits and fragmentation. If this hurts write performance, switch to a time-ordered variant (v7, ULID, or KSUID) on your backend. The UUID generator here is v4 — ideal when storage order doesn't matter or when using hash-based indexes.
Two systems are rejecting my UUID as invalid
Some systems require uppercase hex while others require lowercase; some require the canonical 8-4-4-4-12 format with hyphens, others want the hyphen-less "hex" form. Re-check the format accepted by both systems and convert casing or hyphens as needed — the characters are the same 128 bits either way.
I'm generating thousands of UUIDs and worried about a collision
The birthday-bound probability of a collision after generating 1 billion v4 UUIDs is ~1 in 10¹⁸. In practice, you'll hit hardware or application-level uniqueness failures long before a v4 collision. Trust the math — don't add redundant uniqueness checks unless your system requires them.
Frequently Asked Questions
What's the difference between UUID and GUID?
UUID (Universally Unique Identifier) and GUID (Globally Unique Identifier) are essentially the same thing. UUID is the standard term used in most programming contexts, while GUID is the term commonly used in Microsoft technologies.
Are the generated UUIDs truly unique?
Version 4 UUIDs use 122 bits of randomness, giving over 5.3 × 10^36 possible values. The probability of generating a duplicate is approximately 1 in 2.71 quintillion — effectively zero for any practical purpose.
Can I use these UUIDs as database primary keys?
Yes. UUIDs are widely used as primary keys in distributed databases. They allow records to be created independently on different servers without coordination. However, consider that UUID primary keys use more storage (16 bytes vs 4-8 bytes for integers) and their randomness can hurt B-tree index locality.
What's the difference between UUID v1, v4, and v7?
v1 uses the MAC address and timestamp — deterministic but leaks hardware info. v4 is fully random — the most common choice. v7 is time-ordered (like ULID) — combines the uniqueness of v4 with sortable timestamps, improving index locality for new databases. This tool generates v4.
Are UUIDs secure to use as session tokens?
v4 UUIDs generated from a cryptographic RNG are secure against guessing (122 bits of entropy), but they're still predictable if someone captures a previous UUID and the RNG is weak. For session tokens, always use a CSRNG and rotate tokens on login. Consider longer random strings (256 bits) if you want extra margin.
Can I generate UUIDs in bulk for test data?
Yes — the tool accepts a batch count and generates multiple UUIDs in one click. Copy the batch as a newline-separated list and paste it into a seed script, SQL INSERT, or JSON fixture file.
How do I convert a UUID to/from bytes or Base64?
Strip the hyphens to get a 32-character hex string, then convert each pair to a byte (16 bytes total). Some systems store UUIDs as Base64-encoded bytes to save 6 characters per ID. You can use DevPik's Base64 tool to round-trip between the two formats.
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