UUID Validator

Check if a string is a valid UUID (v4 or v1).

Developer

The UUID Validator checks whether a given string is a properly formatted UUID and reports its version and variant. UUIDs follow a strict format — 32 hexadecimal digits arranged in five groups separated by hyphens (8-4-4-4-12). This tool validates the format, identifies the UUID version (v1 for time-based, v4 for random, etc.), and verifies the variant bits. It is useful for validating API inputs, debugging identifier issues, and ensuring data integrity in systems that use UUIDs. Paste any string and click Validate to get instant results. All validation runs in your browser — nothing is sent to a server.

About UUID Validator

A UUID (Universally Unique Identifier) is a 128-bit identifier standardized by RFC 4122. It is displayed as 36 characters: 32 hexadecimal digits separated by four hyphens in the pattern 8-4-4-4-12 (e.g., 550e8400-e29b-41d4-a716-446655440000). The 13th character indicates the version (1 for time-based, 4 for random, etc.), and the 17th character indicates the variant.

This validator checks the overall format, verifies the version nibble, and confirms the variant bits according to the RFC 4122 specification. It accepts both uppercase and lowercase hexadecimal characters. This is useful for API developers who need to validate incoming UUID parameters, quality assurance engineers verifying test data, and anyone debugging UUID-related issues.

How to Use UUID Validator

  1. Paste or type a UUID string into the input field.
  2. Click Validate to check the format.
  3. The result shows whether the UUID is valid, along with its detected version and variant.

Key Features

  • Format validation — Checks the 8-4-4-4-12 hexadecimal pattern
  • Version detection — Identifies UUID v1 (time-based), v4 (random), and others
  • Variant verification — Confirms RFC 4122 variant bits
  • Case-insensitive — Accepts both uppercase and lowercase hex characters
  • Client-side processing — No server communication; your data stays private

When to Use This Tool

  • Validating UUID parameters in API requests or database inputs
  • Debugging identifier issues where UUIDs may be malformed or truncated
  • Verifying the UUID version used by a system (v1 vs. v4 vs. others)
  • Quality assurance testing to ensure generated UUIDs meet specification
  • Quick checks when working with UUID-based systems and logs

Technical Details

The validator checks the input against the UUID format defined in RFC 4122: 8 hex digits, hyphen, 4 hex digits, hyphen, 4 hex digits (with version nibble), hyphen, 4 hex digits (with variant bits), hyphen, 12 hex digits. The version is determined by the first character of the third group: "1" for v1 (time-based), "4" for v4 (random), "3" for v3 (MD5 hash), "5" for v5 (SHA-1 hash). The variant is determined by the first character of the fourth group: values 8, 9, a, or b indicate the RFC 4122 variant. Both uppercase and lowercase hex are accepted. All validation runs in JavaScript within your browser.

Conclusion

UUID Validator is a quick, reliable tool for checking whether a string is a properly formatted UUID. With version detection, variant verification, and complete browser-side privacy, it is essential for developers and QA engineers working with UUID-based systems. To generate new UUIDs, use the UUID Generator.

Frequently Asked Questions

What UUID versions are detected?
The tool detects the version from the 13th character: v1 (time-based), v3 (MD5 hash), v4 (random), and v5 (SHA-1 hash). The variant bits are also verified.
Is my UUID sent to a server?
No. All validation runs entirely in your browser using JavaScript. Your input never leaves your device.
Are hyphens required?
Yes. The standard UUID format requires hyphens in the 8-4-4-4-12 pattern (e.g., 550e8400-e29b-41d4-a716-446655440000). Both lowercase and uppercase hex characters are accepted.
What is a UUID variant?
The variant indicates which UUID specification the ID conforms to. Most modern UUIDs use the RFC 4122 variant (indicated by the first hex digit of the fourth group being 8, 9, a, or b). Other variants exist for backward compatibility with earlier systems.