UUID Generator
Articles, guides, and in-depth tips for the UUID Generator — everything you need to get the most out of it.
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The Real UUID Collision Risk Isn't Random — It's Container Snapshots and Broken Random Number Generators
Reading a UUID: What the Hex Characters Actually Encode — and Why v1 Exposes Your Server's MAC Address
A UUID looks random but encodes information depending on its version: v1 embeds the creation timestamp and the generating machine's MAC address (recoverable by anyone who sees the UUID); v4 is genuinely random (122 random bits); v5 is deterministically computed from a namespace and name; v7 is timestamp-ordered with random low bits. Here's what each segment of a UUID actually contains, why v1 is a privacy risk in public-facing contexts, and when UUIDs shouldn't be used as security tokens.
UUID Primary Keys in PostgreSQL, MySQL, and MongoDB: Performance Differences and Implementation Patterns
PostgreSQL stores UUIDs as 16-byte native types with no performance penalty. MySQL's InnoDB clustered index makes random UUID v4 fragmentation far worse than in PostgreSQL. MongoDB's ObjectId is 12 bytes with an embedded timestamp. Here's how UUID primary keys actually behave in each database and the ORM patterns to use them correctly.
Beyond UUID: How Twitter's Snowflake IDs, ULID, CUID2, and Nano ID Work
Twitter, Discord, and Instagram all built custom ID systems because UUID couldn't handle time-sortability, distributed generation, and 64-bit constraints simultaneously. Here's how Snowflake IDs work, what ULID and CUID2 offer, and when each alternative makes sense.
UUID v1, v4, v5, v7 Compared — Which Version Should You Actually Use?
UUID v1, v3, v4, v5, and v7 all work differently and suit different use cases. Here's when to use each — including why v7 is now the recommended choice for database primary keys.
UUID Generator — Generate Unique Identifiers for Any Application
Learn what UUIDs are, the differences between versions 1, 4, and 7, when to use UUIDs over auto-increment integers, and how to generate them instantly with a free UUID generator.
