> ## Documentation Index
> Fetch the complete documentation index at: https://docs.speckle.systems/llms.txt
> Use this file to discover all available pages before exploring further.

# Desktop host connectivity

> Connect Speckle from CAD/BIM/structural desktop applications via add-ins or standalone agents.

Decide [publish, load, and integration depth](/developers/connectivity/integration-depth) before choosing add-in vs agent patterns below.

## Host add-in or plugin

**When to use:** Code runs inside a CAD/BIM/structural desktop application (Revit, Rhino, Tekla Structures, ETABS, or a custom host). Users send or receive from that application’s UI.

**Typical stack:**

* C# / .NET in the host process
* [speckle-sharp-sdk](https://github.com/specklesystems/speckle-sharp-sdk) — server and object APIs
* [speckle-sharp-connectors](https://github.com/specklesystems/speckle-sharp-connectors) — DUI, converters, send/receive pipelines

**Reference code:** [Tekla Structures](https://github.com/specklesystems/speckle-sharp-connectors/tree/main/Connectors/Tekla) · [ETABS](https://github.com/specklesystems/speckle-sharp-connectors/tree/main/Connectors/CSi/Speckle.Connectors.ETABS22) · [All .NET connectors](https://github.com/specklesystems/speckle-sharp-connectors)

**Docs:** [Authentication](/developers/authentication/introduction) · [.NET SDK](/developers/sdks/dotnet/introduction) · [Data schema](/developers/data-schema/overview) · [Connector schemas](/developers/data-schema/connector-index)

## Native desktop agent

**When to use:** A standalone tray app, agent, or background service talks to Speckle and optionally calls host APIs (COM, export, file watch)—without living inside the host UI.

**Typical stack:**

* [speckle-sharp-sdk](https://github.com/specklesystems/speckle-sharp-sdk) or [specklepy](/developers/sdks/python/introduction)
* [GraphQL API](/developers/api/graphql) for projects, models, and versions

**Docs:** [GraphQL API](/developers/api/graphql) · [Python SDK](/developers/sdks/python/introduction)

## Related

* [Data & build order](/developers/connectivity/data-and-build) — shared data model and build sequence
* [Cloud & automation](/developers/connectivity/cloud-automation) · [Middleware](/developers/connectivity/middleware) · [Hybrid](/developers/connectivity/hybrid)
* [Resources](/developers/connectivity/resources) — SDK and repository index