Simulate API conditions with Postman Simulator

With Postman Simulator, you can create simulations to test how your service behaves under real-world conditions like latency, errors, and rate limits. Simulations can be applied to mock servers deployed from a mock.

Simulations are most useful when you want to test how your service responds when multiple dependencies fail at the same time. For example, you can combine a mock server that simulates a slow auth service with one that returns errors from an inventory API, then observe how your service handles both conditions together.

Create a simulation

A simulation groups one or more mocks together so you can test them under simulated conditions as a set. You choose which mocks to include when you create the simulation, and you can add or remove mocks later.

Learn how to create a simulation.

Apply scenarios to a simulation

For each mock in a simulation, select a scenario and, optionally, override its conditions without changing the scenario itself. This lets you push a scenario further for a specific test run. For example, overriding a scenario’s 500ms latency to 5000ms for a load test while the original scenario stays unchanged.

Learn how to apply scenarios to a simulation.

Start a simulation

Using the Collection Runner or the Postman CLI, start all mocks in the simulation at once, or start them individually after applying scenarios. Conditions are applied dynamically as your mock handles requests, so you can observe how your service responds to disruptions and identify issues before deploying to staging or production.

Learn how to start a simulation.

View, edit, or update a simulation

After you start a simulation, view its logs to see how the simulated conditions are affecting your API’s behavior. You can also edit or update the mocks and scenarios in the simulation at any time.

Learn how to view, edit, or update a simulation.