CUID Generator
Generate collision-resistant IDs for horizontal scaling
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UUID v4
Random UUIDs. Most commonly used for general purposes.
UUID v7
Time-ordered and random. Best for databases and sorting.
ULID
Sortable 26-char IDs. Perfect for distributed systems.
NanoID
Compact 21-char URL-safe IDs. Great for frontend use.
clh3am5n20000v76duz3k6zztWhat is CUID?
CUID (Collision-resistant Unique IDentifier) was designed specifically for horizontal scaling scenarios where multiple servers generate IDs simultaneously. It combines timestamp, counter, client fingerprint, and random data to virtually eliminate collision risk.
CUID2 is the latest version, addressing security concerns in the original CUID while maintaining its collision-resistance properties. It uses a cryptographic hash function to ensure IDs don't leak information about generation time or machine.
Why Use CUID?
CUID excels in distributed systems where coordination is expensive or impossible. Unlike UUID v1, it doesn't require MAC addresses. Unlike centralized sequence generators, it doesn't create bottlenecks.
The embedded counter handles high-throughput scenarios where the same millisecond sees thousands of ID generations. Each server maintains its own counter, incremented atomically, ensuring uniqueness even under extreme load.
How CUID Works
CUID2 generation:
1. Generate random bytes using CSPRNG 2. Include timestamp for rough time-ordering 3. Add machine fingerprint (hostname hash) 4. Include atomic counter for same-ms uniqueness 5. Hash everything together for uniform distribution
The result is a 24-character string that's URL-safe and horizontally scalable.
Common Use Cases
- Microservices and distributed systems
- High-throughput ID generation
- Serverless functions needing unique IDs
- Multi-region database deployments
Pro Tip
CUID2 is the recommended choice for new projects—it fixes security issues in CUID1 while maintaining performance.
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