StubEngine
Turns plain-English requirements into live mock APIs and manages them in a shared workspace.
What StubEngine can do in ChatGPT
Make live mock APIs from plain English.
Mock Endpoints
Describe an endpoint and get a live mock back.
Error Simulation
Mock failures like a 402 payment error for testing.
Full API Projects
Build several related endpoints in one project.
Shared Workspace
Keep mocks in a workspace your team can use.
Mock Management
List and change existing mocks later.
You stay in control
You approve access, and you can disconnect StubEngine at any time.
Apps 1
What StubEngine does in ChatGPT
The StubEngine plugin turns API requirements written in plain English into live mock APIs. A mock API is a fake version of a real service that returns set responses, so developers can build and test against it before the real one exists.
You can ask for a single endpoint, such as a status check that returns a 200 response with a small JSON body, or a full API project with several related endpoints. You can also mock failures, for example a payment endpoint that returns a 402 error.
Mocks are kept in a shared business workspace, where you can manage them later. The listing says the aim is to cut manual setup so teams can prototype, test and ship integrations faster. That means less time spent writing placeholder code by hand.
Built-in skills
The listing says StubEngine comes with 2 skills. Skills are ready-made instructions ChatGPT can use for a specific job.
- Create API Mock
- Manage API Mocks
Who it is for
- Frontend developers waiting on a backend
- QA testers simulating API errors
- Teams prototyping integrations
How to add StubEngine to ChatGPT
- Open the StubEngine listing in ChatGPT ↗.
- Click Install plugin.
- Sign in to your StubEngine account when asked and approve the access it requests.
- Start a chat and ask for what you need, mentioning StubEngine if ChatGPT does not pick it up.
- To stop, disconnect StubEngine under apps in your ChatGPT settings.
Questions about StubEngine
What is the StubEngine ChatGPT plugin?
The StubEngine plugin turns API requirements written in plain English into live mock APIs. A mock API is a fake version of a real service that returns set responses, so developers can build and test against it before the real one exists. It is listed in ChatGPT's plugin marketplace under Developer Tools.
What can I ask StubEngine to do in ChatGPT?
For example: "Create a GET endpoint /api/v1/status that returns 200 and {"status": "healthy"}", "Create a POST mock payments charge that returns a 402 error", "Build a mock API project for a todo app with list, create and delete endpoints". It also comes with built-in skills such as Create API Mock and Manage API Mocks.
Who makes the StubEngine plugin for ChatGPT?
The ChatGPT listing names StubEngine as the developer. The version listed on 8 October 2026 was 1.0.0.
How do I add StubEngine to ChatGPT?
Open the StubEngine listing in ChatGPT, click Install plugin, sign in to your StubEngine account and approve the access it asks for. Then ask for what you need in a chat, mentioning StubEngine if ChatGPT does not pick it up.
Can StubEngine change things in my account, or only read?
It creates and manages mock API endpoints and projects in your StubEngine business workspace.
Who is the StubEngine plugin for?
Frontend developers waiting on a backend, qA testers simulating API errors and teams prototyping integrations.
Can StubEngine mock error responses?
Yes. The listing's example creates a payment endpoint that returns a 402 error.
Can StubEngine build more than one endpoint at a time?
Yes. It can make a single mocked endpoint or a full API project with related endpoints.
Does StubEngine see my ChatGPT chats?
When StubEngine is connected, ChatGPT may share the parts of your chats and memories that matter for a request with StubEngine. What StubEngine does with that data falls under its own terms and privacy policy. ChatGPT keeps your training-data settings, and you can disconnect at any time.
How do I disconnect StubEngine from ChatGPT?
Open your ChatGPT settings, go to apps, and disconnect StubEngine. You can reconnect later from the listing.
What are alternatives to StubEngine in ChatGPT?
Similar plugins in the ChatGPT marketplace include 3Min API, Neon and AppDeploy. Each has its own page in this directory.
Privacy and your data
When StubEngine is connected, ChatGPT may share the parts of your chats and memories that matter for a request with StubEngine. What StubEngine then does with that data falls under its own terms and privacy policy, not only OpenAI's. ChatGPT keeps your training-data settings for data that comes from connected apps, and you can disconnect at any time.
StubEngine privacy policy ↗StubEngine terms ↗OpenAI: apps in ChatGPT ↗