> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/integrations/builtin/app-nodes/n8n-nodes-base.onesimpleapi.md).

# Use One Simple API in Duaer

Use One Simple API in a Duaer digital organization to call that service. Save the connection under Credentials, then pick a resource and operation on the node. Node note: A toolbox of no-code utilities
## One Simple API in Duaer

One Simple API is an app node in Duaer for calling that service’s API from a digital organization.

The product’s node note is: A toolbox of no-code utilities.

## Credentials and parameters

Credential notes are under [One Simple API credentials](/integrations/builtin/credentials/onesimpleapi.md).

Parameters accept expressions. Tool parameters that an AI Agent should fill use $fromAI. When a run fails, read the error on the node output first.
## Questions

### How do you add One Simple API to a Duaer digital organization?

Open the node panel on the Duaer canvas, search for One Simple API, and drop it onto the digital organization. Connect it after a trigger or a previous node. If auth is required, save the credential first and select it on the node.

### What should you check first when One Simple API fails in Duaer?

Read the error text on that node’s output, then confirm the credential still works and required parameters are filled. For app nodes, also check permissions and quota on the provider side.