Deep Dive: UUID / GUID Generator
A UUID (Universally Unique Identifier) packs 128 bits into a standardized format (RFC 4122), representing 2^122 possible values after reserving bits for version/variant indicators. The collision probability is astronomically low—generating a billion UUIDs per second for 100 years yields roughly 50% chance of one collision. In practice, you'll never see duplicates. The format: 8-4-4-4-12 hexadecimal digits (xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx) where M indicates version (1/4/5) and N encodes variant bits. UUID and GUID are identical—UUID is the RFC standard term, GUID is Microsoft's branding of the same concept.
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UUID Versions: Technical Comparison and Selection Criteria
Struggling with UUID versions? This guide cuts through the complexity of v1, v4, and v7, offering clear technical comparisons and selection criteria to help you choose the perfect identifier for your database and API architecture.
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Privacy Architecture
This tool uses client-side WebAssembly to ensure your data never touches a server. Secure, fast, and 100% private by design.
Core Capabilities
- Multiple UUID versions (v1, v4, v5, NIL)
- Bulk generation up to 1000 UUIDs
- Format options: hyphenated or compact
- Case options: uppercase or lowercase
- Built-in UUID validator for verification
- High-entropy randomness via Web Crypto API
- Privacy-focused: local browser generation
- Download results as text file
Why It Matters
- Collision-Free: Astronomically low probability of duplicate IDs.
- Privacy: IDs are generated locally in your browser—no server tracking.
- Standard Compliance: Fully follows RFC 4122 specifications.
- Developer Friendly: Bulk generation and formatting options save time.
- Versatile: Support for v1 (time-based), v4 (random), and v5 (namespace).
Quick Start Guide
Select the UUID version you need (v1, v4, v5, or NIL).
Choose format options: hyphenated or compact, uppercase or lowercase.
For bulk generation, enter the quantity (up to 1000 UUIDs).
Click 'Generate' to create your UUIDs using the Web Crypto API.
Copy individual UUIDs or download all as a text file.
Common Scenarios
Database Primary Keys
Use v4 UUIDs for secure, distributed primary keys.
Distributed Systems
Coordinate across microservices without ID collisions.
Questions?
Technical Architecture
UUID Version Trade-offs
**UUID v1 (Timestamp + MAC):** Encodes current time plus your network card's MAC address. Sortable by creation time, but reveals machine identity. **UUID v4 (Random):** Pure randomness via crypto.getRandomValues(). No information leakage, most common choice for primary keys. **UUID v5 (SHA-1 Name-based):** Deterministic hashing of namespace + name. Useful for reproducible IDs.
Format & Storage
Standard hyphenated (36 chars) or compact (32 chars). PostgreSQL uses native UUID types; MySQL or SQL Server often store as BINARY(16) or UNIQUEIDENTIFIER for performance.
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Related Articles
Learn more about this tool and related topics in our blog.
UUID Versions: Technical Comparison and Selection Criteria
Struggling with UUID versions? This guide cuts through the complexity of v1, v4, and v7, offering clear technical comparisons and selection criteria to help you choose the perfect identifier for your database and API architecture.
Why Offline Tools Matter for Secure, Sensitive Operations
Privacy isn't a perk, it's a requirement. See why top developers are ditching cloud converters for local-first browser utilities.