Senior JavaScript Engineer

📍Hybrid in Warsaw (3 days/week office)

Your Story:

As a Software Engineer you will be part of our Player team. You will optimize a high-scale infrastructure product with billions of transactions every day, own end-to-end features, and handle the entire development cycle — architecture, implementation, deployment and monitoring. As part of the job, you will work closely with the product, BI, operations, and business teams. Build a great product that will leverage our capabilities and influence directly the way billions of people consume and engage with content over the internet.

Long story short, you will:

• Support 99.999 uptime infrastructure products with billions of transactions every day.
• Collaborate with stakeholders to create a product roadmap and maintain an ongoing technical roadmap.
• Collaborate with the product analysts team to optimize products based on relevant KPIs.
• Improve our development cycle working with DevOps to optimize git flows and CI/CD processes.

Would be awesome if you had:

• 4–5+ years of professional experience as a Software Engineer with a strong focus on TypeScript and Vanilla JavaScript.
• Understanding of core algorithms, data structures, and front-end performance optimization techniques.
• Experience with Micro Services architecture, Event Sourcing, and modern frameworks.
• Good knowledge of client-side architecture; experience in API design is an advantage.
• Basic understanding of databases (SQL / NoSQL) and how front-end applications interact with data layers.
• Familiarity with CI/CD pipelines and the full application release lifecycle from a front-end perspective.
• Exposure to cloud environments (AWS and/or GCP) — infrastructure experience is a plus, not a must.
• Ability to think beyond the UI and understand the bigger product and system picture.
• Experience working with complex projects and features such as SDKs, browser extensions, data-heavy interfaces, or complex front-end architectures.
• High standards for code quality, performance, security, testability, and maintainability.
• Strong documentation skills, including UI logic flows, technical specs, and collaboration with backend and product teams.
• Self-driven mindset and genuine desire to learn and grow in a fast-paced startup environment.

Advantages:

• Experience working in the Ad-tech industry.
• Exposure to Kafka, data streaming, or event-driven systems.
• Prior collaboration with backend or DevOps teams on architecture or infrastructure-related topics.