UUID Version 5 Generator
UUIDv5 • SHA-1 Hashed Namespace & Name
00000000-0000-0000-0000-000000000000
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Generate Bulk UUIDs
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Max 5,000
Formatting & Structure
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No batch active1-click copy available on each row
Deterministic Name-Based•RFC 9562 Section 5.5 / RFC 4122
UUID Version 5 Technical Specification (SHA-1 Namespace)
UUIDv5 generates deterministic, reproducible 128-bit identifiers by hashing a namespace UUID and a name string using the SHA-1 cryptographic digest. Given the identical namespace and input string, UUIDv5 always outputs the exact same identifier.
Bitfield Layout & Binary Structure
Detailed 128-bit byte distribution according to RFC standards.
| Field Name | Bit Range | Purpose & Description |
|---|---|---|
| sha1_hash[0..47] | 48 bits (0-47) | First 48 bits of the SHA-1 hash output. |
| ver | 4 bits (48-51) | Constant binary value 0101 (identifies Version 5). |
| sha1_hash[52..63] | 12 bits (52-63) | Bits 52 to 63 of the SHA-1 hash output. |
| var | 2 bits (64-65) | Constant binary value 10 (RFC standard variant). |
| sha1_hash[66..127] | 62 bits (66-127) | Bits 66 to 127 of the SHA-1 hash output. |
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Advantages & Strengths
- •Deterministic & Idempotent: same inputs guarantee the exact same UUID across any system or language.
- •Zero storage coordination needed: remote services can generate matching IDs without network calls.
- •Far more collision-resistant than MD5-based UUIDv3.
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Considerations & Trade-offs
- •Cannot be reversed or decoded back to the original string.
- •SHA-1 is deprecated for digital signatures, though still safe for non-cryptographic unique identification.
Best Recommended For
- →Consistent entity identification (e.g. converting user emails, domain names, or external IDs to UUIDs).
- →Idempotent API operations and deduplication pipelines.
When to Avoid
- ✕Random token generation or security session keys.
Code Implementation Examples
Python Standard LibraryPython
import uuid
# DNS Namespace
id = uuid.uuid5(uuid.NAMESPACE_DNS, 'bulkuuidgenerator.com')
print(id)Frequently Asked Questions
What standard namespaces are available for UUIDv5?▼
RFC 9562 defines standard pre-allocated namespaces: DNS (6ba7b810-9dad-11d1-80b4-00c04fd430c8), URL (6ba7b811-9dad-11d1-80b4-00c04fd430c8), OID (6ba7b812-9dad-11d1-80b4-00c04fd430c8), and X.500 (6ba7b814-9dad-11d1-80b4-00c04fd430c8).
Is UUIDv5 superior to UUIDv3?▼
Yes. UUIDv5 uses SHA-1 (160-bit digest), which provides far stronger hash distribution and collision resistance than the older MD5 hash (128-bit) used by UUIDv3.