JWT Decoder
Decode and debug JSON Web Tokens, see when they expire, and verify HS, RS, PS, ES, and EdDSA signatures.
UUID Generator
Generate v4, v7, v1, v5, and v3 UUIDs / GUIDs in bulk, and inspect any UUID. Free, private, and 100% in your browser.
Version
v4 (random): 122 random bits. The most widely used UUID.
How Many?
Validate & Inspect a UUID
Generated UUIDs0 UUIDs
What Is a UUID?
A UUID (universally unique identifier), also called a GUID, is a 128-bit value that can be created independently on any machine with practically no chance of a duplicate. That makes UUIDs ideal for database keys, request and correlation IDs, file names, and distributed systems. They are defined in RFC 9562, which replaced RFC 4122 in 2024 and added versions 6, 7, and 8.
0190f2a4-6b3e-7c12-9f4d-2b8e1a7c5d30
^ ^
version variant (8, 9, a, or b)Features
Five UUID versions
v4 (random), v7 (time-ordered), v1 (time-based), and name-based v5 (SHA-1) and v3 (MD5).
Bulk generation
Generate 1 to 10,000 UUIDs at once, then copy them all or download a .txt file.
GUID formats
Switch to uppercase, remove hyphens, or wrap in braces for Microsoft-style GUIDs.
Validator and inspector
Paste any UUID to check it and see its version, variant, and creation time for v1, v6, and v7.
Cryptographically secure
Random bits come from the browser's crypto.getRandomValues, not Math.random.
Private by design
UUIDs are generated on your device. Nothing is requested from or sent to a server.
How to Generate UUIDs in Bulk
- Choose a version: v4 for random IDs, v7 for sortable database keys.
- Enter how many you need (up to 10,000) or pick a preset. For v5 and v3, choose a namespace and enter one name per line.
- Adjust the format: uppercase, without hyphens, or with braces.
- Copy all UUIDs to the clipboard or download them as a text file.
UUID Versions Compared
v4 is fully random and the most common choice. v7 stores a Unix millisecond timestamp in its first 48 bits, so values sort by creation time, which keeps B-tree indexes in PostgreSQL and MySQL compact. v1 uses a 100-nanosecond Gregorian timestamp. v5 and v3 are deterministic and derived from a namespace and a name.
Frequently Asked Questions
Which UUID version should I use?
Use v4 when you just need a unique random ID. Use v7 for database primary keys: it starts with a timestamp, so new rows are inserted in order and indexes stay efficient. Use v5 when the same input must always produce the same UUID. v1 and v3 are mainly for compatibility with older systems.
What is the difference between a UUID and a GUID?
None in practice. GUID (globally unique identifier) is Microsoft's name for a UUID. GUIDs are often written in uppercase and wrapped in braces, like {3F2504E0-4F89-11D3-9A0C-0305E82C3301}. Enable Uppercase and Braces to get that format.
Can two UUID v4 values ever collide?
In theory, yes; in practice, no. A v4 UUID has 122 random bits. You would need to generate about a billion UUIDs per second for around 86 years to reach a 50% chance of a single collision.
Does the v1 generator expose my MAC address?
No. Browsers cannot read your MAC address, and this tool uses a random node ID with the multicast bit set, as RFC 9562 recommends. v1 UUIDs do reveal their creation time, though.
How do v5 and v3 UUIDs work?
They hash a namespace UUID together with a name (SHA-1 for v5, MD5 for v3). The same namespace and name always produce the same UUID, which is useful for stable IDs derived from URLs, domain names, or other keys. Enter one name per line to generate several at once.
Are these UUIDs generated on a server?
No. Every UUID is created in your browser with the Web Crypto API. Nothing is sent to or stored on a server.
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