UUID v4 & v7 Generator Online - Free Universal Unique ID Tool

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122, used to uniquely identify information in computer systems. It is typically represented as a 36-character string in the format 8-4-4-4-12 hex digits.

UUID v1 is time-based, generated from the current timestamp and device MAC address. UUID v4 is random-based, using 122 bits of randomness from a cryptographically secure generator, providing stronger privacy and unpredictability.

For most modern applications, UUID v4 (random) is recommended due to its simplicity and privacy. Use UUID v1 when you need time-based sorting. For database primary keys, consider UUID v7 for better index locality.

Yes, all operations run locally using crypto.getRandomValues(). No data is ever sent to any server. Generated UUIDs never leave your device.

Select your preferred version, choose the quantity, pick your format, and click "Generate UUIDs". Results appear instantly in the output area below.

Yes, you can generate up to 100 UUIDs in a single batch. Results display as a list, and you can copy all at once using the "Copy All" button.

Standard with dashes, without dashes, uppercase, and uppercase without dashes. Output formats include one-per-line, comma-separated, JSON array, and SQL IN.

Yes! Our tool supports multiple output formats including standard with dashes (xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx), without dashes (xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx), uppercase, and uppercase without dashes. You can also choose output formatting options like one per line, comma-separated, JSON array, or SQL IN format for easy integration into your code.

UUID v4 generates completely random identifiers (122 bits of randomness), while UUID v7 incorporates a Unix timestamp (milliseconds) in the first 48 bits followed by random bits. v7 offers time-ordered sorting benefits, making it ideal for database indexes (B-tree friendly). v4 is better when you need pure randomness and no time-based predictability.

Yes! Our tool uses the Web Crypto API (crypto.getRandomValues) for browser-based generation, which is cryptographically secure. For Node.js, you can use the built-in uuid package: npm install uuid, then const { v4 } = require("uuid"); console.log(v4()); Our tool generates the same standards-compliant UUIDs that work across all platforms.

UUID v6, v7, and v8 were defined in RFC 9562 (originally an update to RFC 4122) published in May 2024. UUID v6 is a reordered v1 for better database indexing. UUID v7 uses a Unix timestamp prefix with random bits, making it time-sortable and B-tree friendly. UUID v8 is an experimental format for custom use cases. UUID v7 is gaining adoption as a primary key format in modern databases and ORMs.

Yes, UUID v1 encodes the generating device's MAC address (48-bit node field) and the exact timestamp (60-bit 100-nanosecond intervals). This means anyone with the UUID can determine when and on which device it was generated. For privacy-sensitive applications, use UUID v4 (random) or v7 (time-ordered without MAC). Modern UUID v1 implementations may use random node IDs instead of actual MAC addresses.

ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier that encodes a 48-bit timestamp and 80 bits of randomness using Crockford's Base32. ULIDs are case-insensitive, URL-safe, and lexicographically sortable by time. Compared to UUID v7, ULIDs are more human-readable and have a simpler specification. UUID v7 has the advantage of being an IETF standard. Choose ULID for sortability with readability, or UUID v7 for standards compliance.

UUID v4 (random) causes significant B-tree page splits because new entries insert at random positions. UUID v7 places new entries sequentially in time order, reducing index fragmentation and improving write performance. PostgreSQL and MySQL both benefit from time-ordered UUIDs for primary keys. CockroachDB uses a similar time-ordered scheme by default. For large tables with frequent inserts, UUID v7 offers 5-10x better insert performance compared to UUID v4 due to less index page splitting.