Product Engineer (backend C# .net core) (Greater London)

Job Role: Product Engineer (backend C# .net core)

Reference: BH-355p

Job Type: Permanent

Location: Hybrid, West Hampstead, London (2 days/week in-office)

Salary: up to £75-£80k per annum

About The Client:

Our client builds AI-driven voice automation for regulated industries, helping companies reduce costs while meeting strict compliance standards. Founded by experienced engineers and repeat startup founders, their team combines deep technical expertise with a fast-moving, execution-focused approach.

Overview:

We’re hiring on behalf of our client for a Product Engineer (backend C# .net core) to join their growing team. The role will focus on backend development for a platform that blends telephony, voice AI, and LLMs to create next-generation voice automation features.

You’ll play a key role in building core product functionality, from low-latency backend services to real-time communications and third-party integrations. If you’re proactive, technically strong, and excited about building high-impact systems in a startup environment, this role is for you.

Key Responsibilities:

• Communicate clearly, seek clarification when needed.
• Navigate ambiguity and working with minimal supervision.
• Develop and maintain backend services using C# and .NET Core.
• Design and test REST APIs with JWT-based authentication (OAuth is desirable for the future).
• Write performant SQL for PostgreSQL databases; help design schemas and queries.
• Build and manage WebSocket connections for real-time features.
• Build clean automation tests (unit, functional, API).
• Build minimal UI components using Blazor SSR (checkboxes, graphs ..etc).
• Assist with deployment using Docker (containerisation) and AWS (EC2, RDS).
• Integrate with telephony and AI services like Twilio, ChatGPT, and ElevenLabs.
• Maintain compliance and security in systems handling sensitive financial or personal data.

Requirements/experience:

• 5+ years of software engineering experience.
• Proven backend experience with C# (.NET Core) in Linux-based production environments.
• Comfortable navigating ambiguity and working with minimal supervision.
• Strong SQL knowledge, with experience using PostgreSQL in live systems.
• REST API development experience; understanding of JWT and cookie-based auth.
• Familiarity with Docker and AWS services, from a developer perspective.
• Comfortable with WebSockets.
• Comfortable with building lightweight frontends in Blazor or similar.
• Strong communicator with a startup mentality—proactive, curious, and self-driven.

Additional/Desirable experience:

• Familiar with Terraform, from a developer perspective.
• Previous work in financial services, healthcare, or similarly regulated data environments.
• Experience with LLMs, voice agents, or tools like AWS SageMaker, AWS Bedrock, or ElevenLabs.
• Exposure to soft real-time systems or distributed system architectures.
• Knowledge of OAuth, SQS, or running containers in production.