UUID Generator
Generate UUID v4 and v7 IDs locally with bulk output.
UUID Generator creates version 4 and version 7 universally unique identifiers directly in your browser. Generate a single ID or bulk batches for database seeds, API mocks, and distributed systems—using cryptographically appropriate randomness without uploading anything.
How it works
Select UUID version 4 or 7 and how many IDs you need, then click Generate. Version 4 uses crypto.randomUUID when available; version 7 combines the current millisecond timestamp with random bytes per RFC 9562. Results appear as a newline-separated list ready to copy or download.
Benefits
- Cryptographically secure randomness via Web Crypto APIs
- Supports sortable UUID v7 alongside standard v4
- Bulk generation up to 100 IDs per batch
- No server upload—IDs never leave your browser
Use cases
- Seed test databases with unique primary keys
- Generate correlation IDs for logs and traces
- Create mock API payloads with realistic identifiers
- Prototype time-ordered IDs with UUID v7
Best practices
- Prefer v4 for general-purpose random identifiers
- Use v7 when insertion order or time locality helps indexing
- Store UUIDs as native UUID/binary types in databases when possible
- Regenerate rather than reuse IDs across unrelated resources
Common mistakes
- Assuming uppercase and lowercase UUID strings are different values
- Using UUID strings where sequential integers would be simpler
- Generating IDs without uniqueness constraints in the database
- Confusing UUID v7 time ordering with strict monotonic guarantees
Privacy
UUIDs are generated locally with crypto.randomUUID and crypto.getRandomValues. ToolHub does not receive, log, or store generated identifiers unless you separately enable on-device history.
Frequently asked questions
- What is the difference between UUID v4 and v7?
- UUID v4 is purely random and widely supported. UUID v7 embeds a Unix timestamp in the most significant bits so IDs sort roughly by creation time while keeping strong randomness in the rest.
- Are generated UUIDs cryptographically secure?
- Yes. This tool uses crypto.randomUUID for v4 when available and crypto.getRandomValues for v7 and fallback v4 generation. Values are created locally in your browser.
- Does the UUID Generator upload my IDs?
- No. Every UUID is generated entirely on your device. Nothing is sent to ToolHub servers for this tool.
- How many UUIDs can I generate at once?
- You can generate up to 100 UUIDs per batch. Use Download or Copy to move the list into your app, database seed script, or test data file.
- When should I use UUID v7 instead of v4?
- Choose v7 when you want time-ordered identifiers for database indexes or logs while still using a standard UUID format. Use v4 when you only need random uniqueness.
- Can I copy all generated UUIDs at once?
- Yes. Use Copy to place the full newline-separated list on your clipboard, or Download to save them as a plain-text file.
- Are these UUIDs guaranteed to be unique?
- Collisions are astronomically unlikely for v4 and v7 when generated with proper randomness. For critical systems, still enforce uniqueness constraints in your datastore.
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