Create test fixtures
Give mock records stable-looking, collision-resistant identifiers without querying a database.
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UUID Generator
Generate browser-local UUID v4 identifiers with cryptographically secure randomness for fixtures, client-side records, and safe temporary IDs.
Use UUID v4 generator now.
Generate secure UUID v4 identifiers. Your result updates in the current tab as you work.
UUID Generator
Generate secure UUID v4 identifiers. Nothing you enter here is uploaded or stored.
Secure identifiers, generated in your browser
UUID v4 values are useful when identifiers must be unique without coordinating with a central counter.
UUID v4 values
Generate a batch to create client-side UUID v4 values.
WHAT IT DOES
Useful when a small detail is blocking the next step.
A UUID v4 is a 128-bit identifier produced from random values with fixed version and variant bits. It is useful when a client needs an identifier before a database assigns one, when creating isolated fixtures, or when avoiding coordination around a shared counter. This tool uses the browser’s crypto.randomUUID API.
Assign temporary client IDs
Create an ID for a draft or optimistic record before a server returns its authoritative identifier.
Label support artifacts
Attach a non-sequential reference to a local experiment, screenshot set, or manual test note.
WORKED EXAMPLES
See the exact decision the tool can help you make.
These examples are specific to UUID v4 generator. Replace their values with your own, then use the result as a clue—not as a substitute for application validation.
Create an optimistic client record
A task is added before the API has responded.
INPUT
User clicks “Add task”
RESULT
temp id: 73d0d8aa-2ad7-4d52-b00d-925efe07a40d
The interface can key its temporary row consistently. The server must still authorize the request and decide whether to retain or replace the ID.
Seed test data without accidental collisions
You need distinct mock customers across isolated tests.
INPUT
Generate five values
RESULT
Five UUID v4 identifiers with version 4 and standard variant bits
Random UUIDs avoid a shared incrementing counter that can collide when test workers run in parallel.
HOW TO USE IT
Three deliberate steps.
Use the result to make a decision in your code or content, not merely to produce another value to copy.
- 01
Generate the values
Use the button to create five UUID v4 values from the browser’s secure random source.
- 02
Copy only what you need
UUIDs are identifiers, not human-friendly names. Keep a separate descriptive label where people must recognize the record.
- 03
Let the server stay authoritative
A production server should still validate ownership, uniqueness, and references before accepting a client-supplied ID.
Unique is not secret
UUID v4 values are difficult to guess, but an identifier alone should never grant access. Always check authorization on the server, and do not embed sensitive data in IDs or rely on obscurity for protection.
UUID v4 is excellent for decentralised generation and public-facing opaque identifiers. A database integer can still be best for compact internal indexes. Some systems use both: an internal numeric key and a public UUID.
users
id bigint primary key // internal join key
public_id uuid unique not null // safe external referenceCOMMON PITFALLS
Use the result without creating the next bug.
Each tool is deliberately narrow. These are the mistakes most likely to appear when its output is copied into a real product without checking the surrounding constraint.
Using a UUID as proof that someone owns a record.
Why it matters: An identifier is not authorization, even when hard to guess.
Better approach: Load the record server-side and verify the authenticated actor is permitted to access it.
Assuming client-generated IDs replace database constraints.
Why it matters: Rare collisions, malformed input, and malicious requests are still possible.
Better approach: Keep a unique constraint and validate the expected UUID format on the server.
FAQ
Questions worth answering before you rely on the result.
These tools help with bounded client-side work. Production decisions still need the validation, review, and authorization appropriate to your application.
01Are UUID v4 values guaranteed unique?
They are randomly generated with an extremely low collision probability, but a database unique constraint remains the final protection for important records.
02Can I use a UUID as an API secret?
No. Treat access tokens and secrets as separate credentials with rotation, expiry, storage, and revocation rules.
03Why not use an incrementing number?
Sequential IDs are simple and useful in many databases, but UUIDs avoid coordination and do not reveal approximate record counts in a URL.
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