We just had an actual UUID v4 collision...

I know what you're thinking... and I still can't believe it, but...This morning, our database flagged a duplicate UUID (v4). I checked, thinking it may have been a double-insert bug or something, but no.The original UUID was from a record added in 2025 (about a year ago), and today the system inserted a new document with a fresh UUIDv4 and it came up with the exact same one:b6133fd6-70fe-4fe3-bed6-8ca8fc9386cdWe're using this: https://www.npmjs.com/package/uuidI thought this is technically impossible, and it will never happen, and since we're not modifying the UUIDs in any way, I really wonder how that.... is possible!? We're literally only calling:import { v4 as uuidv4 } from "uuid";const document_id = uuidv4();... and then insert into the database, that's it.Additionally, the database only has about 15.000 records, and now one collision. Statistically... impossible.Has that ever happened to anyone?! What in the...

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An article recounting a rare UUID v4 collision event in a small database.

The pain

Developers and engineers rely on UUID v4 for unique identifiers, assuming collisions are practically impossible; a collision challenges this trust and could cause data integrity issues.

The gap

There is no existing comprehensive investigation or tooling to detect, prevent, or analyze UUID collisions in real-world systems, especially at small scale or in edge cases.

Build angle

Create a tool or service that monitors UUID generation and flags potential collisions early, or educates developers on UUID collision risks and mitigation strategies.

Strengths

  • Highlights a surprising real-world edge case that challenges common assumptions.
  • Could spark awareness about UUID collision risks in software engineering.
  • Leverages a widely used open-source library and a common developer pain point.

Risks

  • UUID v4 collisions are statistically negligible, so market demand for solutions may be very low.
  • The idea is more of a cautionary tale than a scalable business opportunity.
  • Difficult to monetize or build a sustainable product around a rare event.
  • May be perceived as a niche or academic curiosity rather than a pressing problem.

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