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.
Common use cases for platform workflows
These examples cover platform workflows broadly, not specifically Async Mode.
- Running repeatable upload, import, processing, AI, storage, and notification pipelines.
- Tracking long-running media work independently from an application request.
- Referencing centrally stored credentials by name instead of sending storage secrets with each request.
Working with platform workflows
This guidance covers platform workflows broadly, not just Async Mode.
A client authenticates and submits files or references together with workflow instructions. The platform validates the request, schedules dependent operations, records state transitions, and exposes results through a response, polling endpoint, or notification.
Platform concepts become reliable only when their lifecycle is explicit. Authentication, idempotency, retries, timeouts, observability, quotas, and terminal states should be designed together rather than added after failures occur.
What you gain
- Reusable workflows separate application intent from processing infrastructure.
- Stable job identifiers and lifecycle events improve observability and recovery.
- Managed queues and workers let products scale without embedding every media tool.
What it costs
- Synchronous responses are simple but keep connections open while long work executes.
- Aggressive retries improve recovery from transient faults but can duplicate work or overload a dependency.
- Higher concurrency reduces queue time until resource contention or a downstream limit becomes the bottleneck.
Before production
- 1Define authentication, authorization, idempotency, retries, and terminal error behavior.
- 2Observe queue time, execution time, callbacks, and partial results with stable identifiers.
- 3Exercise malformed, duplicate, interrupted, and unauthorized requests before launch.