MongoDB ObjectId Generator
Generate valid 12-byte MongoDB ObjectIDs and parse their internal timestamp.
What is the MongoDB ObjectId Generator?
The MongoDB ObjectId Generator is a free tool that creates valid 12-byte MongoDB ObjectIds and shows the creation timestamp embedded inside each one. You can generate a single ID or a batch, and optionally base the timestamp on a custom date instead of the current time.
A MongoDB ObjectId is a 24-character hexadecimal value made of three parts: a 4-byte Unix timestamp, a 5-byte random value, and a 3-byte counter. Because the timestamp comes first, ObjectIds sort roughly in creation order. This tool builds IDs in that format and decodes the timestamp back into a readable date.
Everything runs in your browser with no signup. The generated IDs never leave your machine, which makes the tool convenient for seeding test data and fixtures.
How to use the MongoDB ObjectId Generator
- 1Set the Number of IDs field to how many ObjectIds you want, between 1 and 100.
- 2Leave Use current timestamp checked to stamp each ID with the current time.
- 3To backdate the IDs, uncheck that box and pick a date and time in the Custom Timestamp field.
- 4Click Generate ObjectID to produce the IDs.
- 5Review each generated ID along with the creation date decoded from its embedded timestamp.
- 6Use the copy icon on any ID, click Copy All to grab the whole batch, or press Ctrl+L to clear.
What you can use it for
- Seeding a MongoDB collection with realistic _id values for development or test fixtures.
- Creating placeholder ObjectIds for API mocks and integration tests before real data exists.
- Generating ObjectIds with a backdated timestamp to test time-based sorting or queries.
- Producing a batch of unique IDs to populate sample documents or demo datasets.
- Inspecting how the timestamp is encoded in the first eight hex characters of an ObjectId.
- Getting a valid 24-character ObjectId quickly without opening a Mongo shell or driver.
Key features
- Generates valid 12-byte, 24-character hexadecimal ObjectIds.
- Batch generation of up to 100 IDs at once.
- Optional custom timestamp so IDs can be dated to any moment.
- Decodes and displays the creation date stored in each ID's first four bytes.
- Copy a single ID or copy the whole batch with one click.
Frequently asked questions
What is a MongoDB ObjectId?
A MongoDB ObjectId is a 12-byte identifier, shown as 24 hexadecimal characters, used as the default _id for documents. It is made of a 4-byte timestamp, a 5-byte random value, and a 3-byte counter, which together keep it unique across machines.
How does the MongoDB ObjectId generator work?
It builds each ID from the three standard parts: the chosen timestamp in seconds as the first four bytes, five random bytes, and a three-byte counter value. The result is a correctly formatted 24-character hexadecimal ObjectId.
Are the generated ObjectIds valid for use in MongoDB?
Yes. The tool produces 24-character hexadecimal strings in the correct 12-byte ObjectId structure, so they are accepted wherever MongoDB expects an ObjectId. For production records, MongoDB normally generates _id values itself.
Can I generate an ObjectId for a specific date?
Yes. Uncheck Use current timestamp and pick a date and time in the Custom Timestamp field. The generator encodes that moment into the timestamp portion of every ID in the batch.
How do I extract the timestamp from an ObjectId?
The first eight hexadecimal characters of an ObjectId are the creation time in seconds since the Unix epoch. This tool decodes that value automatically and shows the creation date next to each generated ID.
Is the ObjectId generator free and private?
Yes. The generator is free, needs no signup, and runs entirely in your browser. The IDs are created locally with JavaScript and are never sent to a server.