> For the complete documentation index, see [llms.txt](https://developer.celigo.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.celigo.com/api/api-reference/connections-and-http-connectors.md).

# Connections & HTTP connectors

Everything needed to reach an external system: the credentials and configuration of a connection, the shared OAuth clients connections reuse, the connector definitions that describe an HTTP application's endpoints, and the agents that reach systems behind a firewall.

Looking for Integration App connectors (the installable applications Partners publish)? Those are under [Marketplace & templates](/api/api-reference/marketplace-and-templates.md).

| Resource                                                                                                                            | What it covers                                                                                         |
| ----------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
| [Connections](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/connections)                           | Credentials and configuration for one external system.                                                 |
| [iClients](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/iclients)                                 | Shared OAuth 2.0 client registrations that multiple connections reuse.                                 |
| [HTTP Connectors](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/http-connectors)                   | Connector definitions that power HTTP connections, exports, and imports.                               |
| [HTTP Connector Endpoints](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/http-connector-endpoints) | The individual endpoint definitions inside an HTTP connector.                                          |
| [HTTP Connector Resources](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/http-connector-resources) | The resource definitions that group an HTTP connector's endpoints.                                     |
| [On-premise Agents](https://developer.celigo.com/api/api-reference/connections-and-http-connectors/on-premise-agents)               | Secure outbound tunnels that let connections reach databases and applications inside your own network. |