Online cuid2 generator
Your generated cuid2
Bulk cuid generator
You can generate up to 1000 cuids at a time using the Bulk Cuid Generator. Select the cuid version you require - either version-1 or version-2 - by selecting it from the drop-down list.
Cuid in a nutshell
Collision-resistant ids optimized for horizontal scaling and binary search lookup performance.
Version 1
Cuid, or Collision-resistant Unique Identifier, is a highly efficient system for generating unique IDs, utilizing timestamps and counters for scalability and fingerprints to prevent collisions among multiple clients, created by Eric Elliott. It excels in speed by allowing quick and synchronous ID generation, eliminating the need for database round trips.Read more about Cuid
Version 2
Cuid2 is the next generation of Cuid, which has been used in thousands of applications for over a decade with no confirmed collision reports. The changes in Cuid2 are significant and could potentially disrupt the many projects that rely on Cuid, so it was decided to create a replacement library and id standard, instead. The Cuid is now deprecated in favour of Cuid2, according to author Eric Elliott.Read more about Cuid2
CUIDv2 is a secure, collision-resistant identifier system designed for use in distributed systems. Using cryptographic hashing (SHA3-512), it combines timestamp data with multiple entropy sources to generate URL-safe IDs, eliminating the metadata leakage present in earlier versions.
CUIDv2 eliminates vulnerabilities associated with host fingerprinting and employs NIST-standard SHA3 hashing. Rather than relying solely on system randomness, it mixes four independent entropy sources (timestamp, counter, crypto random, and session salt), making it resistant to prediction attacks.
With a default length of 24 characters (1.62e+37 bits of entropy), CUID2 has a 50% collision risk after generating approximately 4.03e+18 IDs. This is 13 orders of magnitude better than the theoretical maximum entropy of UUIDv4.
CUID2 IDs contain the following: 1) An initial character for JavaScript (JS) compatibility 2) A 48-bit timestamp 3) A 16-bit counter 4) An 80-bit cryptographic hash 5) Base36 encoding The hashing layer ensures uniform entropy distribution across all characters.
Yes, the time-based prefix of CUIDv2 provides better index locality than random UUIDs while maintaining security. Benchmarks show that inserts are 10-20% faster in large distributed databases due to reduced page splits.
Major implementations include: JavaScript (`@paralleldrive/cuid2`), Python (`cuid2`), Rust (`cuid2`), and Dart (`cuid2`). All ports maintain cryptographic security through SHA3 hashing and proper entropy mixing.
No, CUID2 intentionally avoids using embedded timestamps for security reasons. Although the initial characters are time-based, the hashing layer disrupts the ability to sort them directly in order to prevent metadata leakage and timing attacks.
The valid length range is 2-32 characters. Shorter IDs (e.g., 10 characters) provide 51 million collision-resistant IDs while maintaining security. Entropy increases exponentially with length: entropy = 36^(n-1)*26.
Although CUID2 can use standard random number generators, it should be initialized with cryptographically secure sources, such as the `crypto.getRandomValues()` function in browsers or the `secrets` module in Python, for maximum security.
Choose CUID2 for the following: 1) Client-side ID generation 2) Distributed systems without coordination 3) Security-sensitive contexts 4) Applications requiring both collision resistance and optimal database performance Use NanoID for pure speed and ULID for sortability.