UUID Generator Online — Free Bulk v4 & v1 GUID Maker
Generate UUIDs online for free. Create bulk random UUID v4 and time-based UUID v1 identifiers with RFC 4122 compliance, uppercase, brackets, and array formats — 100% in-browser.
How UUID Generation Works
Pick a version, set your formatting, and export RFC 4122 compliant identifiers in three direct steps.
Choose Version & Count
Select UUID v4 for cryptographically secure random identifiers or UUID v1 for time-based, sortable values, then enter a quantity up to 1,000.
Format and Generate
Toggle hyphenated, plain 32-char hex, {braced} GUID, or quoted array output, switch casing, and click Generate New to fill the sandbox.
Copy or Export the List
Copy the entire batch to your clipboard in one click or export it as a .txt file — ready for seed scripts, fixtures, and database imports.
Utilvo In-Browser vs Server UUID Generators
Why client-side Web Crypto generation outclasses conventional server-based GUID tools in speed and privacy.
| Feature | Utilvo In-Browser | Server-Based Generators |
|---|---|---|
| Randomness Source | OS-seeded CSPRNG via native Web Crypto API | Server PRNG quality varies by implementation |
| Generation Latency | Instant — values never leave your device | Network round-trip and rate-limit queues per request |
| Identifier Privacy | Zero transmission, zero server-side logging | Generated values can appear in server access logs |
| Batch Limits | Up to 1,000 per run with unlimited re-runs | API quotas, daily caps, and paid tier paywalls |
| Offline Capability | Works fully offline once the page is loaded | Requires a live connection for every batch |
Engineering Notes on UUID Construction
How version, variant, and timestamp bits assemble compliant identifiers under RFC 4122 and RFC 9562 specifications.
122-Bit CSPRNG Entropy (v4)
UUID v4 fills 122 of its 128 bits from the browser’s cryptographically secure random source. Only the version nibble (4) and two variant bits are fixed, leaving a keyspace of 2^122 — the foundation of its negligible collision probability.
Gregorian Timestamp Layout (v1)
UUID v1 encodes the 60-bit count of 100-nanosecond intervals since 15 October 1582 into time_low, time_mid, and time_hi_and_version fields, producing identifiers that sort chronologically within the same node.
Version & Variant Bit Discipline
Every generated identifier sets the version nibble in the third group (4xxx or 1xxx) and pins the two most significant bits of the clock sequence to binary 10. This is what makes output parseable by uuid validators in every language runtime.
Deterministic Format Post-Processing
Formatting is applied after generation without touching the underlying 128 bits: hyphens are stripped for plain hex, Windows braces wrap the canonical string, and quoted rows emit syntax-ready array literals for JavaScript, Python, and SQL.
Pre-Flight Checklist for UUID Generation
Follow these recommended checks before exporting identifiers into production databases and codebases.
Match Version to Purpose
Prefer v4 for primary keys, session tokens, and API identifiers; choose v1 only when chronological sortability matters more than privacy.
Match Format to Target
Use {braced} GUIDs for Windows/COM contexts and quoted array rows when seeding JavaScript, Python, or SQL fixtures.
Batch Before You Build
Generate the full quantity your test suite or migration needs in one run, then export the .txt file as a single source of truth.
Never Reuse or Trim IDs
Do not shorten UUIDs or paste a previously generated value twice — every identifier in a batch is drawn fresh from the CSPRNG.
UUID Versions & Identifier Specifications
Comparing the identifier families this tool supports against related standards under RFC specifications.
| Identifier | Standard | Layout | Entropy Source | Role | Best Use Case |
|---|---|---|---|---|---|
| UUID v4 (Random) | RFC 4122 / RFC 9562 | 8-4-4-4-12 hex groups, version 4 nibble | CSPRNG (122 random bits) | Default of this tool | Database primary keys, session tokens, idempotency keys, and object IDs |
| UUID v1 (Time-Based) | RFC 4122 Section 4.1.4 | 60-bit Gregorian timestamp + clock sequence | System clock + random node | Supported version | Chronologically sortable ledger entries and event-sourcing records |
| Windows-Style GUID | RFC 4122 + Microsoft braces | Canonical v4 string wrapped in {braces} | Same CSPRNG source | Formatting option | Windows registry entries, COM interfaces, and .NET interoperability |
| Plain 32-Char Hex | RFC 4122 unformatted | Hyphens removed, 32 hex digits | Same CSPRNG source | Compact format | Cache keys, file names, and storage systems that forbid hyphens |
| Quoted Array Row | RFC 4122 + syntax wrap | Single/double quoted, comma-suffixed | Same CSPRNG source | Code-ready format | Seeding JavaScript, Python, and SQL test fixtures in bulk |
| ULID / CUID (Other) | Non-RFC community specs | Lexicographically sortable encodings | Timestamp + randomness | Not generated here | Alternative schemes for URL-safe or time-ordered identifiers |
Frequently Asked Questions
Understand how in-browser CSPRNG generation creates RFC 4122 compliant UUID v4 and UUID v1 identifiers with 100% privacy.
1How do I generate a UUID online for free?
Set the UUID version (v4 for random or v1 for time-based), choose how many identifiers you need — up to 1,000 at once — then click 'Generate New'. Copy the full list to your clipboard or export it as a text file instantly, with no registration required.
2What is the difference between UUID v4 and UUID v1?
UUID v4 is generated purely from cryptographically secure random values (CSPRNG) and is the most widely used version — collision odds are effectively zero. UUID v1 encodes the current 60-bit Gregorian timestamp plus a random clock sequence and node ID, making its identifiers sortable by creation time. Both follow the RFC 4122 layout: 32 hex digits with version and variant bits set.
3Is it safe to generate UUIDs here for databases and API keys?
Yes, 100%. Generation runs entirely inside your browser using the native Web Crypto API (crypto.randomUUID). No identifier is transmitted, logged, or stored on any server, so values generated for database primary keys, session tokens, or internal API identifiers never leave your device.
4How many UUIDs can I generate at once?
You can batch-generate up to 1,000 UUIDs in a single run, then export the full list as a .txt file or copy it to your clipboard in one click. Re-click 'Generate New' as many times as you like — generation is unlimited and free.
5Can I get UUIDs in uppercase, braces, or as a code array?
Yes. The formatting controls let you switch between standard hyphenated form, plain 32-character hex without hyphens, Windows-style {braced} GUIDs, and quoted array rows ('uuid', or "uuid",) ready to paste into JavaScript, Python, or SQL code. A separate casing toggle converts the whole list to UPPERCASE.
6Are generated UUIDs unique and collision-free?
UUID v4 identifiers draw 122 random bits from a cryptographically secure source, giving a collision probability so small it is negligible in practice — you would need to generate 2.7 quintillion UUIDs for a 50% chance of a single duplicate. UUID v1 adds a timestamp and clock sequence for additional spatial-temporal uniqueness.
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