IDENTIFIERS · LOCAL PROCESSING
UUID Generator
Generate v4 or v7 identifiers, or inspect an existing list for versions, timestamps and duplicates.
Your IDs stay in this browser. Nothing is uploaded or saved automatically.
Choose a version and count, then generate your IDs.
Generate identifiers
1 to 1,000 per batch.
v4 uses secure browser randomness. Identifiers are not passwords, access tokens or a guarantee against collisions.
Your batch
Inspect existing IDs
Use one UUID per line. Canonical hyphenated UUIDs, matching braces or a urn:uuid: prefix are accepted. Letter case does not change an ID.
Up to 10,000 nonempty lines and 1,000,000 UTF-16 text units. Files up to 1 MB. Blank lines are ignored; original line numbers are retained. Imported line endings stay intact until editing.
Inspection result
| Line | UUID or input | Classification | Duplicate of line | Details |
|---|
Classification checks the bit layout, not who issued an ID or whether it is unique elsewhere. Nil and Max are special values. Only v7 timestamps are decoded here.
CSV protects formula-like cells for spreadsheets. JSON retains each original nonempty line exactly.
Read an identifier
RFC example · No IDs have been generated yet.
For v7, the first 48 bits encode milliseconds since 1 January 1970 UTC. This is encoded time, not proof of when an ID was created. IDs within one millisecond use random order; clock changes can affect ordering.
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Versions, limits and privacy
v4 has 122 random bits. v7 combines a 48-bit millisecond timestamp and 74 random bits. Both use the browser’s cryptographic random generator; no weaker fallback is used. Repeated IDs within a batch are retried, but global uniqueness is not guaranteed.
Use v4 when you do not want an embedded timestamp. This tool does not generate name-based IDs, monotonic v7 counters or secret credentials. Existing legacy and reserved bit patterns are identified separately from RFC versions.
Previews show at most 100 rows. Downloads and copies contain every result within the stated limits. Inputs and results remain in memory until this page is closed or reloaded.
Layouts follow RFC 9562.