API for Agencies

API for Agencies As an agency, you can use the same REST API your clients use, but point individual requests at one of your managed sub-accounts instead of your own account. This lets you build tooling that onboards a client end to end — creating their campaigns, training their AI on a knowledge base, importing their contacts, connecting their messaging channels, and buying phone numbers — all without logging into each sub-account by hand. This page covers only the agency-specific behaviour: how to act on behalf of a sub-account with the sub_account_id parameter. For the basics (generating a key, authentication, base URL, error format, rate limits), start with the API Access guide. Everything there applies here too — you authenticate with your agency account's API key. 📝 Note: This page is technical. If you are not a developer, share it with the person building your integration. How "acting on behalf of" works By default, every API request acts on the account that owns the API key — your agency account. To act on a managed client account instead, add the optional sub_account_id parameter to the request, set to that client's account id. Omit sub_account_id → the request acts on your own agency account. Include sub_account_id → the request acts on that sub-account, but only after the platform confirms the sub-account is really yours. You always authenticate with your agency account's API key. You never need the sub-account's own key, and you never handle the sub-account's cred