Senior Backend Engineer( AdTech)

Sigma Software

About The Position

The Senior Backend Engineer will take end-to-end ownership of Vast Gateway, a high-throughput edge proxy built on Cloudflare Workers that handles tens of millions of requests per day in the video advertising delivery flow. The service retrieves and processes VAST responses, applies modifications including malicious-ad protection logic for VPAID creatives, and consolidates multiple VAST documents into a single XML response for video players. The platform prioritizes low latency, high availability, scalability, and operational stability. The role involves maintaining and extending the platform, designing scalable backend solutions for high-load environments, supporting client onboarding and integrations, and building customer-specific features. The engineer will monitor system performance and reliability, improve observability, participate in releases and production support, and collaborate with Product and engineering stakeholders to evolve the platform architecture. The position calls for an analytical, data-driven professional with strong ownership, autonomy, troubleshooting skills, and a focus on reliability and quality.

Requirements

At least 5 years of commercial backend development experience.
Strong expertise in server-side JavaScript or other backend technologies.
Commercial experience in AdTech environments.
Proven experience supporting production systems in high-load environments.
Strong understanding of debugging, monitoring, hotfixing, and zero-downtime deployments.
Solid knowledge of HTTP protocols, web fundamentals, HTML, and tracking pixels.
Experience building scalable and highly available distributed systems.
Strong analytical and problem-solving skills.
Ability to independently own services and drive technical improvements.
Upper-Intermediate English level or higher.
Strong communication and collaboration skills in distributed teams.

Nice To Haves

Experience with the VAST protocol.
Hands-on experience with Cloudflare Workers.
Experience with VPAID creatives.
Background in video advertising technologies.
Experience with high-load distributed systems.
Performance optimization expertise.
Experience with edge-computing architectures.

Responsibilities

Take end-to-end ownership of the Vast Gateway service.
Maintain, develop, and extend platform functionality.
Design and implement scalable backend solutions for high-load environments.
Support onboarding of new clients, including integrations, monitoring setup, troubleshooting, and optimization.
Build custom features and integrations based on customer requirements.
Monitor system performance and proactively identify optimization opportunities.
Ensure service reliability, availability, and low-latency performance.
Participate in release planning, deployments, and production support activities.
Improve observability through monitoring, alerting, and operational tooling.
Collaborate with Product and engineering stakeholders to evolve platform architecture.