What is Async Mode?
Async Mode lets a client continue after its request or upload completes while Transloadit processes the Assembly separately. When the Assembly specifies a notify_url, an Assembly Notification later delivers the results to the client’s back end.
How Async Mode works
Async Mode changes the request lifecycle, not the processing graph: the client is released once submission is complete while the Assembly continues on service infrastructure. Final data arrives through the notification sent to the configured notify_url rather than an interactive response held open for the full job, which avoids client and proxy timeouts for costly media work. Applications that cannot receive notifications can poll the Assembly Status URL until a terminal state appears. The application must maintain durable correlation state and expose its own pending, succeeded, or failed job experience.
Key facts
- 1The initial response confirms handoff rather than successful media output, so a user-facing system needs a separate state between accepted submission and terminal completion.
- 2Assembly Notifications are sent only when the Assembly specifies a
notify_url, and receiving them requires a reachable server endpoint. A browser tab or mobile process is not a dependable receiver; clients without a server endpoint should poll the Assembly Status URL for completion. - 3Retries and out-of-order application events are normal distributed-system concerns, so the receiver should key updates by Assembly identity and reject stale state transitions.
When Async Mode matters
Choose Async Mode when processing may outlast an interactive request or should not block the client, and set notify_url so results reach your back end. The receiving endpoint must authenticate notifications and handle retries or duplicate deliveries safely; integrations without a server endpoint can poll Assembly Status instead.