Senior C# / .NET Developer - NetSapiens Integrations

**Job Description**

We are looking for a senior C\# / .NET / NetSapiens developer based in Brazil for a remote contract role focused on telecom and call\-center systems integration.

**This is not a generic .NET position.** A key requirement is hands\-on experience with the NetSapiens platform, including its APIs and subscription\-based event model. We need someone who already understands how NetSapiens works in practice and can build reliable software around live telephony and operational data.

The role involves backend and integration work within our existing technology stack, including C\#, .NET / .NET Core, SignalR, SQL Server, Azure containers, and .NET Aspire. You will help build secure APIs, real\-time services, internal tools, and operational applications that integrate NetSapiens data with our own systems.

Because part of the work involves reading technical documentation and communicating with our U.S. team, strong written English is required, especially for technical reading, writing, and email communication. Fluent spoken English is a strong plus.

**Responsibilities**

* Build and maintain backend services that integrate with NetSapiens.
* Consume, process, and store data from NetSapiens APIs and subscription\-based events.
* Develop secure internal and external REST APIs.
* Build real\-time and near\-real\-time application features using SignalR or similar technologies.
* Design and maintain SQL Server data models for operational and reporting workloads.
* Wor...