Backend Engineer (.NET) – WhatsApp/WABA

The role

You will build and maintain core backend services for messaging infrastructure. The role focuses on WhatsApp integrations, APIs, and messaging workflows.

What you will do

• Design, build, and maintain backend services using C#, .NET, and ASP.NET Core.
• Build and maintain integrations with the WhatsApp Business Platform (WABA), WhatsApp Cloud API, and related Meta APIs.
• Develop and maintain WhatsApp messaging workflows, including message sending and receiving, webhooks, templates, delivery statuses, and messaging events.
• Design and maintain RESTful APIs.
• Integrate Sent's platform with Meta/WhatsApp, carrier networks, third-party messaging providers, and internal services.
• Build reliable systems for processing asynchronous messaging events, retries, failures, and high-volume traffic.
• Monitor and improve the reliability, performance, and scalability of backend services.
• Identify bottlenecks, optimize database queries, and evolve database schemas.
• Troubleshoot production issues and external API or messaging integration failures.
• Participate in technical design and architecture discussions.

Required qualifications

• 3+ years of professional experience with C# / .NET / ASP.NET Core building production backend services.
• Hands-on experience with the WhatsApp Business Platform (WABA), WhatsApp Cloud API, or WhatsApp Business APIs.
• Experience working with WhatsApp messaging workflows, including webhooks, message templates, delivery statuses, and messaging events.
• Strong experience designing, building, and maintaining RESTful APIs.
• Strong understanding of asynchronous systems, webhooks, queues, retries, and event-driven architectures.
• Solid knowledge of relational databases, including schema design, efficient queries, and data integrity.
• Strong understanding of authentication, authorization, API security, and secure backend development.
• Experience troubleshooting production integrations and third-party API failures.
• Strong security and reliability mindset.
• Strong written and verbal English communication skills.
• Ability to work effectively with engineering, product, and other cross-functional teams.

Nice to have

• Experience with WhatsApp Business Solution Providers (BSPs), Meta Business Manager, phone number onboarding, or WABA configuration
• Experience with CPaaS, telecommunications, SMS, RCS, messaging infrastructure, or high-volume communication platforms
• Experience building high-availability or high-throughput systems

Benefits

• Work with an experienced engineering team on products used by customers worldwide.
• Work on high-scale messaging infrastructure across WhatsApp, SMS, RCS, and other communication channels.
• Meaningful ownership of the systems and integrations you build.
• Competitive salary based on experience.
• Career growth opportunities in a fast-growing US technology company.
• Private health insurance (including 50% family coverage).
• Monthly gym membership allowance.
• Modern office in central Prishtina.
• Snacks, coffee, and refreshments in the office.
• Regular company and team activities.
• In accordance with Kosovo Labor Law.

About the company

Sent is building the messaging infrastructure that powers how businesses communicate with their customers. They provide a unified API for SMS, WhatsApp, iMessage, and RCS.