Skip to main content
When you import an OpenAPI file, you can ask Requestly to build a mock server from it in the same step. Pick Create a collection + mock server in the import preview and Requestly does two things in order: it imports the file as a collection of requests, then generates a mock server from that collection. You keep both. Under the hood this is the same generator that runs when you create a mock from a collection, so the routes, responses, and summary counts mean the same thing. The difference is that you never have to import first and generate second.
The generated mock starts serving the moment it is created, and anyone with its URL can call it without signing in. Scan your spec’s example responses for anything real before you import.

​
Prerequisites

  • You are signed in and a cloud project is active. Mock servers are cloud-only, so in a local project the option is not shown at all.
  • Your role has permission to create mocks in the project. Without it the option appears greyed out, and the reason takes the place of its description.
  • The spec defines at least one operation. A spec with no paths cannot be mocked, and the option is greyed out before you import rather than failing afterwards.
  • The spec is small enough to mock. If it would produce a collection with more requests than mock generation supports, the option is greyed out and the reason names the limit and the count that exceeded it.
Unlike Create a spec and Create a spec + collection, this option is not restricted to OpenAPI 3.x, to a single file, or to files up to 16 MB. Swagger 2.0 files, multi-file imports, and files above the 16 MB spec ceiling all work, because no API specification is created: the mock is built from the imported collection. The importer’s own 100 MB per-file limit still applies.
A greyed-out option never blocks the import. Leave Create a collection selected, import the file, and generate the mock later from the collection’s Create mock server menu item.

​
Generate the mock

1

Start the OpenAPI import

Click Import in the API Client and choose OpenAPI, then select your .yaml or .json file. Requestly parses the file and shows the import preview.
2

Choose Create a collection + mock server

In the What to create list, select Create a collection + mock server. It is the last of the four options.Selecting it reveals a notice about what the mock will expose. The notice is informational: it does not block the import and there is nothing to acknowledge.
The What to create options in the OpenAPI import preview with Create a collection plus mock server selected and the public exposure notice below it
3

Import

Click Import. The collection is imported first, and then the window switches to Creating the mock server while the mock is built.Large specs are generated in the background and can take a few minutes. You can close the window while that runs: it does not cancel anything, and Requestly notifies you when the mock is ready. A mock created while the window was closed is already serving and publicly reachable, so open it from the Mocks section and click Stop if you are not ready for that.
4

Review the summary

When generation finishes, the window reports what was produced: how many routes and responses were created, and what was dropped or could not be mapped. See Read the generation summary for what each row means.
The import window showing Mock server created with the counts for routes created, responses created, requests unmapped, routes with no response, responses dropped, and routes shadowed
5

Open the mock and call it

Click Open mock. The mock opens in an editor tab and is already serving, so the URL strip offers Stop rather than Start. Copy the base URL, append a route path, and call it:
You get back the example response that the spec declared for that operation.

​
What gets generated

The imported collection is created alongside the mock and stays in your sidebar. The mock takes its name from that collection, which comes from the spec’s info.title. Names longer than 120 characters are shortened, and a file with no title falls back to OpenAPI Import.
The mock is a snapshot. Re-importing the spec does not update an existing mock, and editing the collection afterwards does not change the mock either. Each import creates a fresh collection and a fresh mock.
Every generated route is set to the Rules-based selection mode, and one response per route is marked as the default. Add matching rules when you want a route to answer differently depending on the request.

​
Read the generation summary

All six rows always appear, zeros included, so a zero is a statement that nothing was quietly lost. The four rows that report a loss carry an information icon; hover or tab to it for the same explanation inside the app. Below the counts, the summary states that templated paths match any value, so a call to /pets/42 reaches the route built from /pets/{petId}.
This summary is shorter than the one you get when you generate from a collection. Requests skipped, Paths wildcarded, and Extra endpoints from examples are not shown, because an OpenAPI file cannot produce any of them: it holds only HTTP operations, its templated paths are already parameters, and its examples always belong to the operation they are declared under.
If some of the spec failed to import, the summary says so above the counts and tells you how many items failed. The mock covers less than the spec does in that case. Fix the failures in the collection, then generate a new mock from it through the collection’s menu.

​
Importing several spec files at once

You can select more than one OpenAPI file in a single import. Each file becomes its own root collection, and each root collection gets its own mock. The summary reports the first mock in full, and lists the rest under Other specs in this import with their route and response counts. A spec that produced no mock is listed there as no mock, and a warning above the counts names it. Its collection is still imported, so you can generate its mock later from the collection’s menu.

​
When the mock is not created

The collection is imported and committed before generation starts, so a failure here never costs you the import. The window reports what happened, names the collection that landed, and the button reads Keep collection. There is no retry button. To try again, use the imported collection’s own Create mock server menu item, which re-runs generation against the collection you already have.
One message reads Mock creation is still finishing: generation ran longer than Requestly waits for and is probably still running. Check the Mocks section before creating another one.