CUID vs ULID vs UUID: Choosing the Right Unique ID for Your App
Compare CUID, ULID, and UUID for unique identifiers. Evaluate sortability, collision resistance, size, and ecosystem support for each format.
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Tags: developer-tools, uuid, identifiers
CUID vs ULID vs UUID: Choosing the Right Unique ID for Your App UUID is the standard, but it is not always the best tool. ULID and CUID were both designed to address specific shortcomings of UUID — one optimizing for sortability and readability, the other for distributed collision safety and fingerprinting resistance. This guide compares all three (plus CUID2 and nanoid) with a concrete decision framework. |---|---|---|---|---| | Length (text) | 36 chars | 36 chars | 26 chars | 24 chars | 21 chars (default) | | Charset | hex + hyphens | hex + hyphens | Crockford Base32 | lowercase alpha+digits | URL-safe (A-Za-z0-9-) | | Sortable | No | Yes (ms) | Yes (ms) | No | No | | Timestamp embedded | No | Yes | Yes | No | No | | Random bits | 122 | 74 | 80 | ~128 | ~126 | | Standardised | RFC 9562…
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