SHA-1 Name-Based UUID Generator (v5)
Generate repeatable, name-based version 5 UUIDs using SHA-1 hashing and namespaces.
SHA-1 over MD5
Version 5 UUIDs are generated in the exact same deterministic manner as version 3, but they replace the deprecated MD5 hashing algorithm with the much more secure SHA-1 algorithm.
Because SHA-1 produces a 160-bit (20-byte) hash and standard UUIDs can only hold 128 bits (16 bytes), the algorithm securely truncates the resulting hash to fit into the standard UUID data structure without losing the collision-resistant properties that developers require for database mapping.
Native Web Crypto
This tool implements the SHA-1 generator using the native `crypto.subtle.digest` API built directly into modern browsers.
This guarantees that your sensitive internal project names, user IDs, or API paths are hashed locally on your own machine. We never transmit your inputs or the resulting identifiers to external servers.
Frequently Asked Questions
What is the difference between UUID v3 and v5?
Both versions are deterministic and require a namespace and a name. The only difference is the hashing algorithm used. UUID v3 uses the older MD5 hash, while UUID v5 uses the more secure SHA-1 hash. RFC 4122 recommends using v5 for all new applications.
How does UUID v5 hashing work?
Version 5 UUIDs combine the raw bytes of a 16-byte Namespace UUID and your text string, calculate the 20-byte SHA-1 hash of that combined data, truncate it to 16 bytes, and format it into standard UUID structure.
Is my text string sent to a server?
No. This tool uses the native Web Crypto API built directly into your web browser to perform the SHA-1 hashing locally. Your internal data names and URLs never leave your computer.