I once watched two production database rows collide on a hand-rolled ‘unique’ ID scheme, ‘user’ + timestamp + random two digits, which collided the moment two signups landed in the same second. Homemade uniqueness is a bug waiting for scale. UUIDs are 128 bits of engineered uniqueness with collision odds so low you can ignore them forever.
Generate single or batch UUID v4 values instantly, ready to paste into databases, APIs, filenames, or test fixtures. Version 4 (random) is the default for good reason: no coordination needed, no central registry, uniqueness by mathematics rather than by hoping.
Try it now: open the free tool, runs 100{e0bed9560a59d6d3feee569f5ae3dad3ee14a646b3fccc2d16becbf099999e03} in your browser.
Usage notes from production: store UUIDs in native UUID columns (Postgres) or BINARY(16), not VARCHAR(36), the text form wastes space and index performance. Never use UUIDs where sequential, guessable IDs are a security boundary (use random tokens with sufficient entropy instead, different problem). And for test data, generate a fresh batch per run rather than reusing fixtures; shared IDs across test suites create the spookiest intermittent failures.
Bottom line: v4 for identity, native columns for storage, fresh batches for tests.
Your turn: use the tool free here, no signup, nothing leaves your device.
How do you use UUID v1 / v4 / v5 Generator Suite?
Open the UUID v1 / v4 / v5 Generator Suite in your browser (Generate UUIDs in any version and quantity). Type or paste your input, adjust the options, and copy the result. Everything runs locally on your device with no account and nothing stored, so the three steps below take seconds even for confidential work.
- Choose the kind of output you need.
- Adjust any options to shape the result.
- Generate, then copy the result with one click.
Try UUID v1 / v4 / v5 Generator Suite free. It opens right in your browser.