UUID Generator — Free Online Tool Generate UUIDs: v1 (timestamp), v4 (random), v5 (namespace). Bulk UUID generation, validation, format conversion. GUID generator online.
Use this free online UUID Generator directly in your browser. No signup required, no data leaves your device. Part of Utilier — a collection of 133+ developer utilities.
What is UUID Generator (v1, v4, v5, GUID, Bulk Generate, Validate)? UUID (Universally Unique Identifier) generator creates 128-bit unique identifiers in format 8-4-4-4-12 hex digits (xxxxxxxx-xxxx-4xxx-xxxx-xxxxxxxxxxxx) with versions: v1 timestamp-based, v4 random secure, v5 namespace SHA-1 hash, validation checking format and version correctness, and bulk generation for multiple IDs at once.
UUID v4: Random 122-bit value with 6 fixed bits. Format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. Most common, cryptographically random.UUID v1: Timestamp + MAC address based. Sortable by creation time. Reveals MAC address (privacy concern).UUID v5: Namespace + name hashed with SHA-1. Deterministic: same input → same UUID. Use for reproducible IDs.Bulk generate: Create 10, 100, 1000 UUIDs at once. Each guaranteed unique. Copy all as list.Validation: Check format: 8-4-4-4-12 hex, version bits correct. Detects invalid or malformed UUIDs.Why use uuid generator? Guaranteed unique IDs without coordination. No database sequence needed.
No collisions: UUIDs virtually collision-free (2^122 possible v4 UUIDs). Safe to generate independently.Distributed systems: Generate IDs in multiple systems without conflicts. No central ID server.Database keys: Primary keys without auto-increment. Works with replication, sharding.API identifiers: Request IDs, transaction IDs, session tokens. Unique across services.When to use uuid generator Use when unique identifiers needed without centralized coordination.
Database primary keys (distributed databases). API request/response IDs. File names (ensure uniqueness). Session tokens. Transaction identifiers. Message queue message IDs. How to use uuid generator Select UUID version, generate, copy result.
Select version: v4 (random, most common), v1 (timestamp-based, sortable), v5 (namespace, deterministic).Generate: Click Generate. Creates new UUID: 123e4567-e89b-12d3-a456-426614174000.Bulk generate: Enter count: 100. Generates 100 unique UUIDs. Copy all as list.Validate UUID: Paste UUID. Check format: valid 8-4-4-4-12 hex, correct version bits.Key features Multiple versions: v1 (timestamp + MAC), v4 (random), v5 (namespace SHA-1 hash).Bulk generation: Generate 1-10,000 UUIDs at once. Each guaranteed unique.Format options: Lowercase, UPPERCASE, no dashes (32 hex chars), braces {uuid}.Validation: Checks: 8-4-4-4-12 format, hex chars only, version bits (4xxx for v4).Collision-free: Cryptographically random v4. 2^122 possible values (astronomically large).Common use cases Database IDs: Primary key: id UUID DEFAULT uuid_generate_v4(). No auto-increment, works with replication.File names: Upload file: photo-123e4567-e89b-12d3-a456-426614174000.jpg. Guaranteed unique name.Session tokens: User session: sessionId = UUID v4. Unique per session, hard to guess.Examples UUID examples for different versions.
UUID v4 Generate random UUID550e8400-e29b-41d4-a716-446655440000Random. Notice '4' in 3rd group (version 4).
Bulk generate Count: 5123e4567-e89b-12d3-a456-426614174000
234f5678-f90c-23e4-b567-537725285111
...5 unique UUIDs generated.
Technical reference UUID format and version specifications.
Format 8-4-4-4-12 hex digits: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx. M = version (4 for v4), N = variant (8, 9, a, b). v4 122 random bits + 6 fixed (version, variant). Example: 123e4567-e89b-42d3-a456-426614174000 (4 in 3rd group = v4). v1 Timestamp (60 bits) + clock sequence (14 bits) + MAC address (48 bits). Sortable by time. Privacy: reveals MAC. v5 SHA-1(namespace UUID + name). Deterministic: same namespace + name → same UUID. Reproducible IDs. Common mistakes to avoid Using v1 (exposes MAC address) Why it happens: UUID v1 includes MAC address (privacy leak). Can identify machine.
How to avoid it: Use v4 (random) for privacy. v1 only if need timestamp sorting.
Frequently asked questions Can UUIDs collide (duplicate)? Theoretically yes, practically no. v4 has 2^122 possible values. Collision probability astronomically low (generate trillion/second for 100 years = 50% collision chance).
Should I use UUIDs as database primary keys? Pros: no sequence, works with replication/sharding, distributed generation. Cons: larger than INT (16 bytes vs 4), slower index lookups, not sortable (v4). Use if need distributed ID generation.
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