Developer Tools · Integration
OpenAPI
Add OpenAPI to your product for your customers, and give your AI agents governed access to it.
OpenAPI is a specification for describing REST APIs, not a vendor you sign up with, and this connector exists so your product can call any API that ships one. Each customer supplies their own OpenAPI or Swagger document plus the base URL and credentials for the service it describes, and the operations, parameters and response shapes come from that document rather than from code you wrote. That is how you support a customer's internal service, or a long-tail vendor with no named connector, without a release on your side. fastn owns the credential storage, retries, pagination and per-tenant isolation, and the same governed connection is what your AI agents use.
In your product
Embedded for your customers. Per-tenant auth, no per-customer code, maintained by fastn.
Let customers connect an API your product has never seen by supplying its OpenAPI description, a base URL and credentials.
Generate the callable operations from the specification so adding an endpoint is configuration rather than a code change.
Map request parameters and response fields per customer so one flow serves many differently shaped services.
Call a customer's own internal service from your product with their credentials rather than a shared key.
For your AI agents
Governed, audited access for the agents you build, through the MCP server.
An agent reads the specification to see which operations exist before it decides what to call.
An agent calls an approved read operation and grounds its answer in the customer's own service data.
An agent runs a write operation within the methods and paths you allow, with every request logged.
Example prompt
Using this OpenAPI spec, list the operations available and then fetch the record for customer 4412.
Set up OpenAPI in 4 steps
- 01Enable the OpenAPI connector in your fastn dashboard.
- 02Have each customer supply their OpenAPI or Swagger document, the base URL and authentication details for the service.
- 03Choose which operations your product exposes and map the request and response fields, per customer.
- 04Call them from your product and expose the same connection to your agents through the MCP gateway.
Why teams use the OpenAPI integration
What you get by embedding it with fastn instead of building it yourself.
- Ship an OpenAPI integration without building it. Your customers point it at their own endpoint and credentials and work their services, builds and deployments through it, with no per-customer code on your side.
- Handle the part that actually costs time: these systems emit a lot of webhooks, and replay after downtime has to be handled. fastn owns the auth, token refresh, rate limits, pagination and breaking-change fixes, so an OpenAPI update is not your on-call problem.
- One integration serves your product and your agents. The same governed OpenAPI connection powers in-product features and gives AI agents scoped, audited access, so you connect engineering activity to the rest of the business without wiring it twice.
Used by these teams
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PostgreSQLOpenAPI integration FAQ
How do I add an OpenAPI integration to my product?
Enable the OpenAPI connector in your fastn dashboard, then let each customer authenticate their own OpenAPI account. fastn handles the OAuth flow, token storage and refresh per tenant, so there is no OpenAPI client code in your app and no per-customer branch in your codebase. Setup is 4 steps.
How is an OpenAPI connection configured per customer?
OpenAPI is a specification rather than a service you sign up for, so there is no OpenAPI account. Each customer supplies their own endpoint and credentials, and that connection is scoped to them, so they only ever reach their own services, builds and deployments. The per-tenant isolation works the same way it does for a vendor product.
Can AI agents use this OpenAPI integration?
Yes. The same connection is exposed to your agents through the fastn MCP gateway, with permissions scoped per tenant and every call audited. An agent reads the specification to see which operations exist before it decides what to call.
Who maintains the OpenAPI integration?
fastn does. When OpenAPI changes an endpoint, deprecates a field or alters its auth, the fix lands in the connector rather than in your backlog, and your customers' connections keep working.
Can I react to OpenAPI events in real time?
Yes, through event triggers. Events are delivered per tenant and can be replayed after an outage, so a webhook missed during downtime is not silently lost.
Can an agent open or update items in OpenAPI?
Yes, within scoped permissions, and every action is audited so an agent's changes are attributable.
What can I build with the OpenAPI integration?
A common starting point: connect an API your product has never seen by supplying its OpenAPI description, a base URL and credentials. Teams also use it for the other use cases listed above, and expose it to agents for governed reads and writes.
How much does the OpenAPI integration cost?
It is included. Pricing is based on connected accounts, not on how many connectors you enable, so adding OpenAPI does not change your per-connector cost. You can start free with 3 connected accounts.
Add OpenAPI to your product
Start free with 3 connected accounts. No sales call required, and no per-customer integration code.