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ObjectId Generator

Generate MongoDB-style ObjectIds: 24-character hex IDs built from a Unix timestamp, random bytes and an incrementing counter. Perfect for seed data, test fixtures and prototyping document databases.

ObjectId options

12-byte IDs: timestamp, random, counter.

Press Generate ObjectIds.

Everything runs locally. Nothing is sent to any server.

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How ObjectId works

A MongoDB ObjectId is 12 bytes shown as 24 hex characters: a 4-byte Unix timestamp, a 5-byte random value unique per process, and a 3-byte incrementing counter. The timestamp leads, so ObjectIds sort roughly by creation time, and the counter guarantees uniqueness when many IDs are minted in the same second.

Why ObjectId exists

ObjectIds shine as distributed-friendly primary keys: any application server can mint one without asking the database, so inserts never block on ID generation. The embedded timestamp also lets you extract creation time later, which is exactly what the companion ObjectId timestamp tool does.

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ObjectId Generator FAQs

Are these real ObjectIds I can use in MongoDB?
Yes. Any 24-character hex string works wherever an ObjectId is accepted, in seed scripts, test fixtures, API payloads and database shells. They follow the real layout: timestamp plus random plus counter.
Do ObjectIds sort by creation time?
Yes. The first 8 hex characters are the Unix timestamp in seconds, so sorting ObjectIds as strings is roughly the same as sorting by creation time, down to one-second precision.
Can two ObjectIds collide?
The 5 random bytes plus the 3-byte counter give about 2^64 combinations per second per process, so collisions are practically impossible unless a process generates over 16 million IDs in a single second.
ObjectId vs UUID, which should I use?
Use ObjectId when you need time-ordered, database-friendly keys you can generate on any server. Use UUID v4 when you need a formal standard with no time information, or v7 for time-ordered IDs outside MongoDB.
How do I read the timestamp from an ObjectId?
Take the first 8 hex characters, parse them as a hexadecimal integer, and you have the Unix timestamp in seconds. Paste the ID into the ObjectId timestamp tool on this site to see the date instantly.
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