Backend Developer (AdTech)

Keystone AI is a Ukrainian venture builder that connects ambitious tech businesses with the international stage, fostering an ecosystem for rapid growth. We unite visionary founders and diverse talent to create companies that drive global progress. Our portfolio features over 10 projects spanning Adtech, Martech, Mobile apps, and more. We’re looking for a Backend Developer to build and develop AdTech publishment services — systems responsible for ad serving, traffic delivery, and monetization logic. Experience with OpenRTB or integrations with ad networks is a strong plus. You’ll join our core backend team, led by the CTO — a group of experienced engineers building the infrastructure behind ad delivery and monetization. The team works within a stable business model and has strong expertise in developing scalable, data-driven AdTech platforms. What you will be doing: build and maintain scalable Node.js services (ES6+); improve application performance through profiling, optimization, and best practices; enhance, refactor, and modernize existing codebases; design efficient data models and work with SQL/NoSQL databases, including query optimization and caching; write and maintain unit and integration tests, and contribute to high-quality code through code reviews; troubleshoot and resolve production issues in Linux environments, ensuring system stability and reliability. What you bring: hands-on experience with RTB / DSP / SSP / ad serving pipelines; 3–5+ years of backend development experience with Node.js, Go, or Python; strong understanding of asynchronous and concurrent programming; experience building high-throughput / low-latency systems; strong SQL skills (MySQL/PostgreSQL): indexing, query optimization, execution plans, transactions; hands-on experience with Redis/MongoDB and caching strategies; confident debugging and profiling skills; solid understanding of HTTP/TCP and distributed systems; strong command of Linux CLI and Git; clean code approach with focus on performance, scalability, and reliability. Bonus skills: AdTech / OpenRTB 2.x/3.x (auctions, bid req/resp, schain, ads.txt/sellers.json); ClickHouse, Aerospike, Nginx; parallel/stream data processing; experience with high-load/distributed systems; Kafka or RabbitMQ. What we offer you: flexibility and freedom: choose fully remote, hybrid, or office-based work yourself; strong team: work alongside some of the industry’s top talent; unlimited growth: grow in multiple directions, get freedom to launch your own product; career development: take courses, attend top-notch conferences, explore digital library for nonstop growth; health support: get medical insurance, paid vacation and sick leaves, and access to a corporate psychologist; fun and culture: enjoy off site parties, team-buildings, sport events, and corporate gifts. Thanks for your time. Lets bring things to the next level? Originally posted on Himalayas