Build metadata

Buildhub is a database of metadata for official Mozilla builds of Firefox, Thunderbird, and Fennec (legacy Firefox for Android). Support for the new Firefox for Android is being tracked in bug 1622948.

It includes data on the build id and revision, which can help you understand what changes went into a specific version of the product you see in telemetry.

Buildhub data is exported to BigQuery as it becomes available (generally very soon after our software is released) at mozdata.telemetry.buildhub2.

The build column contains a struct value that matches the structure of the buildhub.json files built by during a Firefox build.

An example of a build record is:

  "build": {
    "as": "/builds/worker/workspace/build/src/clang/bin/clang -std=gnu99",
    "cc": "/builds/worker/workspace/build/src/clang/bin/clang -std=gnu99",
    "cxx": "/builds/worker/workspace/build/src/clang/bin/clang++",
    "date": "2019-06-03T18:14:08Z",
    "host": "x86_64-pc-linux-gnu",
    "id": "20190603181408",
    "target": "x86_64-pc-linux-gnu"
  "download": {
    "date": "2019-06-03T20:49:46.559307+00:00",
    "mimetype": "application/octet-stream",
    "size": 63655677,
    "url": ""
  "source": {
    "product": "firefox",
    "repository": "",
    "revision": "ed47966f79228df65b6326979609fbee94731ef0",
    "tree": "mozilla-beta"
  "target": {
    "channel": "beta",
    "locale": "en-US",
    "os": "linux",
    "platform": "linux-x86_64",
    "version": "68.0b7"

The fields of build are documented in the schema.

Notably, the timestamp in reflects the publication date of the build on This is earlier than the moment that the build would have been offered to clients through either the download website or the in-product updater.

To find the earliest publication date for each release in the Firefox 82 series, you can use a query like:

    MIN( AS published
FROM mozdata.telemetry.buildhub2
    AND ENDS_WITH(build.source.repository, "mozilla-release")