Generate UUIDs, Strings & Serial Numbers Free
Quick answer: A UUID (Universally Unique Identifier) is a 128-bit value used to
uniquely identify database records, API objects, or files — the chance of collision is
astronomically small. This tool generates UUIDs using your browser's built-in
crypto.getRandomValues() function (cryptographically secure, unlike
Math.random()), plus custom random strings and sequential serial numbers for inventory
or licensing use. Generate 1 to 1000 at once, entirely in your browser.
🔒 Security: This tool uses the Web Crypto API for true randomness — suitable for tokens, API keys, and session identifiers.
📊 Bulk limit: Up to 1000 items per batch keeps your browser responsive; run multiple batches for larger needs.
✅ Privacy: Everything is generated locally in your browser. Nothing is uploaded to any server.
Choose a Generator Type to get started
🆔 UUID Settings
✅ 100% Private & Secure: All generation happens in your browser using the Web Crypto API. Nothing is ever uploaded to a server.
How to Generate IDs Online
Pick a Generator Type
Choose UUID, Random String, or Serial Number based on your need.
Configure Settings
Set length, format, quantity, and character options.
Generate & Export
Click Generate, then copy individual results or export the full batch.
🔐 Why Cryptographic Randomness Matters
Many free ID generators rely on JavaScript's Math.random(), which uses a predictable
pseudo-random algorithm not suitable for anything security-sensitive. This tool uses
window.crypto.getRandomValues() — the same secure random source used by password managers
and cryptographic libraries — ensuring your UUIDs and tokens are genuinely unpredictable.
Database Primary Keys
Generate UUIDs for database records instead of sequential integers, avoiding ID collision across distributed systems.
API Keys & Tokens
Create secure random strings for API authentication tokens or session identifiers.
Inventory Serial Numbers
Generate sequential, formatted serial numbers for products, invoices, or asset tags.
Test Data Generation
Quickly populate development or QA databases with realistic unique identifiers.
Coupon & Voucher Codes
Generate unique, hard-to-guess promotional codes for marketing campaigns.
Asset Tracking Labels
Pair generated serial numbers with your Product Label Generator for physical asset tags.
Key Features of This Generator
- 3 Generator Modes: UUID/GUID, Random String, and Sequential Serial Number.
- Cryptographically Secure: Uses the Web Crypto API, not predictable Math.random().
- Bulk Generation: Create 1 to 1000 IDs in a single click.
- Full Format Control: Uppercase, hyphen removal, braces, custom character sets, ambiguous character exclusion.
- Sequential Serials: Custom prefix, suffix, starting number, increment, and zero-padding.
- Multiple Export Options: Copy individually, copy all, or download as TXT/CSV.
- 100% Browser-Based: No installs, no server uploads. All processing is client-side.
- Free Forever: No limits, no watermarks, no account required.
UUID & Random ID Generator – Complete Guide
Unique identifiers are the backbone of modern software systems — from database records to API tokens to physical inventory tags. Choosing the right type of identifier for your use case matters: a database record typically needs a UUID, an API key needs a cryptographically random string, and a physical product needs a human-readable sequential serial number. This tool covers all three scenarios in one place.
UUID Versions Explained
| Version | How It's Generated | Best For |
|---|---|---|
| Version 4 | 122 bits of pure randomness | Database keys, general-purpose unique IDs (most common choice) |
| Version 1 | Timestamp + random node identifier | Systems needing rough chronological ordering |
| Nil UUID | All zeros: 00000000-0000-0000-0000-000000000000 |
Placeholder/default value in testing |
Generator Type Comparison
| Type | Example Output | Typical Use |
|---|---|---|
| UUID v4 | f47ac10b-58cc-4372-a567-0e02b2c3d479 |
Database primary keys, distributed systems |
| Random String | aB3$kL9pQmZ2 |
API tokens, passwords, session IDs |
| Serial Number | INV-00001 |
Invoices, inventory, licensing keys |
How the Generation Engine Works
- Secure Random Byte Generation: The tool calls
window.crypto.getRandomValues()to fill a typed array with cryptographically secure random bytes, sourced from your operating system's entropy pool. - UUID v4 Assembly: Per RFC 4122, specific bits are set to mark the UUID as version 4 and variant 1, while the remaining 122 bits come directly from the secure random source.
- Random String Mapping: Each random byte is mapped to an index within your selected character set (uppercase, lowercase, digits, symbols, or a custom set) using modulo reduction with bias correction.
- Serial Number Assembly: Sequential numbers are zero-padded to your specified width and wrapped with your custom prefix/suffix, incrementing by your chosen step for each subsequent item.
- Duplicate Prevention: For random string generation, each result is checked against previously generated values in the same batch to avoid accidental duplicates.
Recommended Settings by Use Case
| Use Case | Generator Type | Recommended Settings |
|---|---|---|
| Database Record ID | UUID v4 | Lowercase, with hyphens |
| API Secret Key | Random String | 32+ characters, all character sets enabled |
| User-Facing Coupon Code | Random String | 8 characters, exclude ambiguous, uppercase + digits only |
| Invoice Numbers | Serial Number | Prefix "INV-", 5-digit padding, increment by 1 |
| Product Asset Tags | Serial Number | Prefix with year, 6-digit padding |
Security and Privacy Considerations
- Zero Network Transfer: All generation happens directly in your browser using JavaScript and is never transmitted to any server.
- Cryptographically Secure Source: Uses the Web Crypto API rather than Math.random(), making outputs suitable for security-sensitive use cases like tokens.
- No Data Storage: Generated values exist only in your browser's memory during your session. Nothing is logged or persisted.
- No Server-Side Generation: Unlike some online generators that create IDs server-side (and could theoretically log them), everything here is generated locally.
Troubleshooting Common Issues
Explanation: If only one character set (e.g., digits only) is enabled with a short length, results will naturally look similar. Solution: Enable more character sets (uppercase, lowercase, symbols) and increase the length for more visual variety.
Explanation: If your starting number already has more digits than your padding setting, padding has no visible effect. Solution: Increase the padding value to exceed your highest expected serial number's digit count.
Explanation: If you enter duplicate characters in the custom set field, some characters have a higher chance of appearing. Solution: Ensure each character in your custom set appears only once.
Explanation: Very long random strings (200+ characters) combined with 1000 quantity requires significant secure random byte generation. Solution: Reduce quantity or length, or generate in smaller batches.
Frequently Asked Technical Questions
Question 1: What is the Web Crypto API and why is it used here?
Answer: The Web Crypto API is a browser standard providing access to
cryptographically strong random number generation via window.crypto.getRandomValues().
Unlike Math.random(), which uses a fast but predictable algorithm, this API sources
randomness from your operating system's secure entropy pool, making it suitable for
security-sensitive applications.
Question 2: How many possible UUID v4 values are there?
Answer: A UUID v4 has 122 truly random bits (6 bits are fixed to indicate version and variant), giving 2^122 ≈ 5.3 × 10^36 possible values — a number so large that random collisions are considered practically impossible even at massive generation scale.
Question 3: Is Version 1 UUID generated here fully RFC-4122 compliant?
Answer: This tool generates a simplified timestamp-based UUID variant using the current timestamp plus secure random bits for the node identifier portion, rather than an actual MAC address (which browsers cannot access for privacy reasons). For most practical timestamp-ordering use cases, this works identically; strict RFC compliance for distributed systems may require a server-side library.
Question 4: What does "bias correction" mean in random string generation?
Answer: When mapping random bytes (0-255) to a character set of arbitrary size (e.g., 62 characters) using simple modulo division, characters at the start of the set can appear slightly more often. This tool uses rejection sampling to discard biased byte values, ensuring truly uniform character distribution.
Question 5: Can I use generated UUIDs as database primary keys safely?
Answer: Yes, UUID v4 is widely used as a primary key type in production databases (PostgreSQL, MySQL, MongoDB all support it natively), particularly useful in distributed systems where multiple servers generate IDs independently without coordination.
Frequently Asked Questions (FAQs)
Yes, this tool is 100% free with no limits, no signup, and no watermarks.
This tool uses the Web Crypto API, a cryptographically secure random number generator built into your browser, rather than the less secure Math.random() function.
Practically no. A version 4 UUID has 122 random bits, giving over 5.3 undecillion possible values. Collisions are not expected even at massive scale.
Yes, use Serial Number mode with your desired prefix (e.g., "INV-"), starting number, and zero-padding to generate sequential invoice numbers instantly.
Absolutely. Everything is generated locally in your browser. Nothing is uploaded to any server.
Yes, use the "Download TXT" or "Download CSV" buttons to export your entire batch as a file.
A UUID, or Universally Unique Identifier, is a 128-bit value used to uniquely identify records, objects, files, API resources, and other data in software systems. UUIDs can be generated independently without relying on a central database sequence or ID server.
UUID v1 is based on a timestamp and node identifier, while UUID v4 is generated primarily from random values. UUID v4 is commonly used when you need a highly unpredictable unique identifier, while UUID v1 can be useful when time-based generation is required.
For most general-purpose applications, UUID v4 is a common choice because it is generated from cryptographically secure random values. UUID v1 can be useful for time-based or legacy compatibility requirements. Choose the version that best matches your application's requirements.
UUID and GUID are closely related terms for globally unique identifiers. GUID is commonly used in Microsoft environments, while UUID is the more general term used across software platforms. Both are typically represented as 128-bit identifiers.
Yes. UUIDs are commonly used as database identifiers and primary keys, especially in distributed applications where multiple systems need to generate IDs independently. Before choosing a UUID strategy, consider your database type, indexing requirements, storage format, and expected data volume.
Yes. You can format generated UUIDs using the available uppercase, no-hyphen, and brace options. These options change the displayed format to match the requirements of your programming language, database, API, or software system.
A cryptographically secure random string is generated using a secure source of randomness rather than a predictable function such as Math.random(). This tool uses your browser's Web Crypto API to generate random values for supported generation modes.
Yes. You can generate random strings using uppercase letters, lowercase letters, numbers, symbols, or a custom character set. You can also adjust the length and quantity to create IDs or strings for your specific use case.
Yes. Serial Number mode lets you create sequential numbers with a custom prefix, suffix, starting number, increment value, and zero padding. This can be useful for invoices, product asset tags, inventory records, licenses, orders, and internal reference numbers.
Yes. You can generate UUIDs, random strings, or sequential serial numbers in bulk. The current tool supports generating up to 1,000 items in a batch, which you can copy or export as TXT or CSV.
Final Thoughts
Whether you need a cryptographically secure UUID for a database, a random token for API authentication, or a sequential serial number for inventory tracking, this free tool covers all three use cases with proper cryptographic randomness — entirely in your browser, with instant bulk export.
Choose a generator type above to start creating your IDs now!