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Free online tool
Generate cryptographically secure UUIDs instantly and securely in your browser. Supports UUID v4, v7, and v1 singly or in bulk.
Privacy: All generation occurs locally in your browser. No data is sent to any server.
A UUID (Universally Unique Identifier) is a 128-bit label used to identify information in computer systems without requiring a central registration authority. UUIDs are essential in distributed systems, databases, APIs, and microservices where multiple independent systems need to create unique identifiers simultaneously without risk of duplication. This free online UUID Generator creates cryptographically secure UUIDs in three versions — v4 (random), v7 (time-ordered), and v1 (time-based) — entirely in your browser. The generated UUIDs are never sent to any server or stored anywhere.
The generator uses the Web Crypto API for all randomness requirements. For UUID v4, crypto.randomUUID() or a polyfill fills 122 random bits into the standard 8-4-4-4-12 format. For UUID v7 (RFC 9562), the first 48 bits encode the current Unix timestamp in milliseconds, followed by 4 version bits, 12 random bits, 2 variant bits, and 62 more random bits — producing identifiers that are both unique and chronologically sortable. UUID v1 constructs a 60-bit timestamp from 100-nanosecond intervals since October 15, 1582, combined with a clock sequence and a random node ID with the multicast bit set. All formatting, casing, and output wrapping happens client-side in real time.
You are building a REST API and need 10 time-sortable primary keys for a new database table.
You have 10 RFC 9562-compliant UUID v7 identifiers formatted as a JSON array, ready to paste into your database migration or seed file.
Yes. All UUID generation happens entirely in your browser using local client-side JavaScript APIs. No information is ever sent to any remote server or stored anywhere.
UUID v4 is fully random and is the most common format. UUID v7 encodes a millisecond-precision Unix timestamp in its first 48 bits, making it sortable and optimal for database primary keys. UUID v1 is time-based and uses 100-nanosecond intervals along with a node ID.
Since UUID v7 is sequential (time-ordered), databases can insert new rows much faster. Standard random UUIDs (like v4) cause index fragmentation in database B-Trees because they are inserted randomly, whereas v7 maintains sequential insert patterns.
Since browsers do not expose the device's physical MAC address for privacy reasons, a cryptographically secure random node ID is generated once per session with the multicast bit set, complying with RFC 4122 specifications.
For UUID v4, the probability of collision is astronomically low — roughly 1 in 2^122 (about 5.3 × 10^36). You would need to generate over a billion UUIDs per second for 86 years to have a 50% chance of a single duplicate.
UUIDs are the backbone of identity in modern distributed systems. This free UUID Generator gives you instant access to all three major versions — v4, v7, and v1 — with flexible formatting and bulk generation, entirely in your browser. Whether you are building APIs, seeding databases, or debugging existing identifiers, this tool has you covered without compromising your data privacy.