Export an Amplitude behavioral cohort asynchronously using the Behavioral Cohorts API

Steps

1. Authenticate all requests using HTTP Basic Authentication with your Amplitude API key as the username and your secret key as the password.
2. List available cohorts with GET https://amplitude.com/api/3/cohorts to identify the cohort ID and confirm its size — cohorts over 2 million users cannot be exported via this API and require a cohort sync instead.
3. Initiate the async export by sending GET https://amplitude.com/api/5/cohorts/request/{cohort_id}; optionally append ?props=1 to include all user properties or ?propKeys=email,plan to include specific ones. The response returns a request_id.
4. Poll the job status with GET https://amplitude.com/api/5/cohorts/request-status/{request_id} until async_status returns JOB COMPLETED (HTTP 200); a still-running job returns HTTP 202 with JOB INPROGRESS.
5. Download the cohort file with GET https://amplitude.com/api/5/cohorts/request/{request_id}/file — small cohorts return data inline; large cohorts redirect (HTTP 302) to a pre-signed S3 URL that expires after one minute, so download immediately.