Senior Backend Engineer - Spark team

Title: Senior Backend Engineer - Spark team Location: Warsaw, Kyiv, Remote

Spark is a cross-platform email client, available on iOS, macOS, Android and Windows. Our mission has always been to help people fall in love with the email again, filter out the noise, and focus on what's important. Some of our most loyal users have been with us almost since day one. More than 19 million users have downloaded Spark and turned their emails from a constant distraction into a clear, manageable workflow.

Recognized with Apple's Editor's Choice in 2015 and the Golden Kitty Award for Productivity on Product Hunt in 2022.
About the role:
As a Senior Backend Engineer, you’ll own features end to end, from design and decomposition to delivery in production. You’ll architect robust Go services within a distributed system: scaling databases, syncing data across devices, building integrations with other services (e.g., calendars), and optimising the performance of critical components. AI-assisted development is now a natural part of our workflow, giving you the reach to work across many parts of the product.
What you’ll do:

• Own features end to end: design, decompose, estimate, coordinate with teammates, and ship to production
• Build and evolve Go services that handle sync, integrations, and data processing at scale
• Optimise queries and data access on large MySQL tables, and design async processing flows
• Keep the system healthy: investigate alerts, dig into logs in Kibana, metrics in Grafana, and pods in Kubernetes
• Test your own changes before they reach users, and review code in backend repositories
• Contribute to the frontend parts of your features (desktop and iOS clients), using AI agents to work efficiently across the stack
• You’ll start with backend only and gradually take on client-side work as you get to know the product

About you:

• Solid Go experience with strong hands-on coding
• Experience building large features with full ownership, from idea to production
• Strong knowledge of database optimisation (indexing, query tuning, working with large tables)
• Experience with async processing and distributed systems: queues, retries, failure handling, consistency
• Practical Kubernetes experience: deploying, debugging, investigating issues
• Confidence using AI coding tools, and the judgment to review and verify what they produce
• Some experience with any frontend technology, and readiness to contribute to client-side code when a feature requires it