UUID v4 Generator
UUID v4 Generator uses crypto.randomUUID() and exposes a How many? field even though its title is singular. Blank, zero, negative, or nonnumeric counts fall back or clamp to at least one; values above 100 clamp to 100. Each line is a standard random version-4 UUID. The page does not reserve identifiers in a database, check prior outputs, attach meaning, or guarantee application-wide uniqueness.
Runs locally — files stay on your deviceHow many UUIDs can this page generate?
From one through 100 per run.
Version 4 uses random bits plus fixed fields
A v4 UUID has 122 random bits after setting version and variant fields. Collision probability is extremely low, but uniqueness is not mathematically guaranteed.
How it works
The count is converted to a number, bounded to 1–100, and crypto.randomUUID is called independently for each output line.
Key concepts
Random, not ordered
v4 values do not naturally sort by creation time.
Identifier is not capability security
An unguessable-looking ID does not enforce access control.
When to use it
- Create opaque test identifiers.
- Generate client-side correlation IDs.
- Seed a small fixture set.
When not to use it
- Do not encode timestamps or business meaning.
- Do not replace a database uniqueness constraint.
- Do not use an ID alone as an authorization secret.
Worked examples
Default
- Input
Blank count- Expected output
One UUID
Nonnumeric/blank falls back to one.
Batch
- Input
Count 5- Expected output
Five lines
Each call is independent.
Large request
- Input
Count 500- Expected output
100 lines
The maximum is enforced.
Common mistakes
Assuming reservation
Generation does not insert into your system. Correction: Persist with a uniqueness constraint.
Sorting as time
v4 has no creation-order field. Correction: Store timestamps separately or choose an appropriate version.
Using as a password
Identifiers and secrets have different lifecycle requirements. Correction: Generate dedicated secrets.
Best practices
- Keep database uniqueness constraints.
- Treat identifiers as public unless protected separately.
- Use the expected UUID version across integrations.
Related operations and differences
Base64 Decoder
Choose Base64 Decoder when you need to decode Base64 into readable text.; use UUID v4 Generator specifically for uuid.
Base64 Encoder
Choose Base64 Encoder when you need to encode text as Base64 in your browser.; use UUID v4 Generator specifically for uuid.
Binary to Text
Choose Binary to Text when you need to decode 8-bit binary groups into text.; use UUID v4 Generator specifically for uuid.
Hex to Text
Choose Hex to Text when you need to decode hexadecimal bytes into text.; use UUID v4 Generator specifically for uuid.
HTML Escape
Choose HTML Escape when you need to escape HTML-sensitive characters.; use UUID v4 Generator specifically for uuid.
HTML Unescape
Choose HTML Unescape when you need to decode HTML entities into characters.; use UUID v4 Generator specifically for uuid.
Limitations and privacy
- One to 100 v4 values only.
- No namespace, timestamp version, uppercase option, compact form, persistence, collision lookup, or deterministic seed.
The entered value is transformed locally in this browser and is not sent to the Toolbox server.
Copying or pasting sensitive output into another service is a separate disclosure decision.
Frequently asked questions
Are outputs uppercase?
Browser UUIDs are normally lowercase canonical strings.
Can a collision happen?
It is possible in principle but extraordinarily unlikely with proper randomness.
Are values stored?
No.
Why can this page make multiple UUIDs?
Its shared generator UI includes a count field.