For common services like Google Drive, Slack, or AWS S3, use the Integrations Task instead—it connects to 3,500+ services from the Integrations Marketplace and is simpler to set up.
Key Capabilities
Any REST API
Connect to any HTTP endpoint, public or private.
Flexible Authentication
Support for Bearer tokens, API keys, Basic auth, JWT, or no auth.
Full Control
Configure HTTP method, headers, and request body.
Structured Output
Returns request details and service response for downstream processing.
When to Use It
Use External Service when you need to call a custom API:- Connect to proprietary internal APIs
- Access public APIs without built-in integrations
- Send data to webhook endpoints
- Fetch data from specialized services
The 5 Configuration Areas
To call an API, you’ll configure these five things:| Area | What It Does |
|---|---|
| Authentication | How to authenticate: Bearer token, API key, Basic auth, JWT, or none |
| Endpoint URL | The full URL of the API you’re calling |
| HTTP Method | The action: GET (fetch data), POST (send data), PUT, DELETE, PATCH |
| Content Type | Format of your request (usually application/json) |
| Request Body | The data to send (for POST, PUT, PATCH requests) |
Authentication Options
| Type | Use Case |
|---|---|
| None | Public APIs that don’t require authentication |
| Bearer Token | APIs using OAuth2 or API tokens |
| API Key (Header) | APIs that accept keys in custom headers |
| Basic Auth | APIs using username/password authentication |
| JWT | APIs requiring signed JSON Web Tokens |
Output
The External Service task always returns two output variables:| Output | Type | Description |
|---|---|---|
| Request Details | Object | Contains information about the request that was made |
| Service Response | Text | The raw response from the API |
To parse or extract specific fields from the Service Response, add an Opus Agent task after External Service to process and structure the data.
How to Add External Service
1
Drop it into your workflow
Drag an External Service task into your workflow where you need to call an API.
2
Enter the endpoint
Type the full API URL and select the HTTP method (GET, POST, etc.).
3
Set up authentication
Choose the authentication type and provide credentials if needed. For public APIs, select “None”.
4
Configure the request
Add any required headers and configure the request body.
5
Test it
Run a preview to verify the API call works and returns the expected response.
6
Parse the response
Add an Opus Agent task after External Service to extract specific fields from the Service Response.
Tips for Better Results
Test your API outside Opus first
Test your API outside Opus first
Before configuring External Service:
- Test the API with a tool like Postman or curl
- Verify your credentials work
- Understand the response structure
Handle errors gracefully
Handle errors gracefully
APIs can fail for various reasons:
- Check the response for success/failure status
- Use a Decision Agent to handle error responses
- Add fallback paths for when calls fail
Keep credentials secure
Keep credentials secure
Protect your API credentials:
- Use organization-scoped credentials for shared APIs
- Never hardcode secrets in request bodies
- Use variables for sensitive values