Transloadit

What is a Job Slot Limit?

A Job Slot Limit is the concurrency allowance that comes with a Transloadit subscription plan and applies per Workspace in each processing region. Priority Job Slots bound how many weighted Encoding Jobs can run in the Live Queue at once, and a separate batch job slot allowance bounds concurrent batch work; live jobs beyond the priority allowance wait in a Backup Queue until slots free up.

Request + files
Processing platform
Results + status
A processing platform accepts an authenticated request, executes a workflow, and returns observable results. This diagram shows platform workflows broadly, not specifically Job Slot Limits.

How Job Slot Limits work

The limit is a weighted concurrency budget rather than a simple count of files or Assemblies. Each active job claims a Robot-specific number of slots; for example, an image resize claims five and a video encode claims sixty. The total is evaluated for the Workspace within each processing region. Overflow beyond the priority allowance waits in a Backup Queue and retains its intended queue, which is different from deliberately assigning a Step to the Batch Queue. Planning therefore uses the mix and duration of operations, not upload volume alone.

Key facts

  1. Robot types have different slot claims, so the same limit can admit many lightweight image operations but far fewer simultaneous video encodes.
  2. Priority and batch job slot allowances apply per processing region, so traffic distribution across regions can change observed concurrency without any plan change.
  3. Exceeding the limit does not fail jobs: excess live work trickles into a Backup Queue and is re-enqueued to the Live Queue as the Workspace’s slots free up, while a step-level queue setting can intentionally send nonurgent work to the shared Batch Queue.

When Job Slot Limits matter

Plan capacity around the slot costs of the Robots you use and the latency your urgent work requires. When live jobs exceed the Priority Job Slots, the excess waits in a Backup Queue and returns to the Live Queue as running jobs complete; higher or custom limits come from upgrading the plan or arranging an add-on with support rather than from a settings page.

Common use cases for platform workflows

These examples cover platform workflows broadly, not specifically Job Slot Limits.

  • 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 Job Slot Limits.

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

  1. Define authentication, authorization, idempotency, retries, and terminal error behavior.
  2. Observe queue time, execution time, callbacks, and partial results with stable identifiers.
  3. Exercise malformed, duplicate, interrupted, and unauthorized requests before launch.

Turn media knowledge into a working pipeline

Connect uploads, processing, AI, storage, and delivery through one declarative API — with the encoding stack, scaling, and format churn handled for you.

Try Transloadit for free