Export a filtered set of Marketo leads in bulk using the Bulk Lead Extract REST API

Steps

1. Obtain an OAuth 2.0 access token via the Marketo identity endpoint and pass it as an Authorization: Bearer header on all subsequent requests — do not use the access_token query parameter, which is scheduled for removal.
2. Create the export job by sending POST /bulk/v1/leads/export/create.json with a JSON body specifying the fields array, the format (CSV, TSV, or SSV), optional columnHeaderNames, and exactly one filter — e.g., {"createdAt": {"startAt": "...", "endAt": "..."}} — covering a range of 31 days or fewer.
3. Enqueue the job by sending POST /bulk/v1/leads/export/{exportId}/enqueue.json using the exportId returned in the create response; the job status will move to Queued and then Processing.
4. Poll job status with GET /bulk/v1/leads/export/{exportId}/status.json no more than once per minute until status returns Completed; the job queue holds a maximum of 10 jobs and runs at most 2 concurrently.
5. Download the file with GET /bulk/v1/leads/export/{exportId}/file.json; use an HTTP Range header to support resumable partial downloads if the file is large.
6. If the job is no longer needed, cancel it with POST /bulk/v1/leads/export/{exportId}/cancel.json to free the queue slot.