Backend Engineer – Senior – Go – Product & Startup Experience – Saily

Details

Saily is looking for a backend engineer to build and improve a secure mobile data product used by millions of paying customers across more than 200 destinations. The role involves end-to-end product ownership, from shaping ideas with Product and Design through shipping, measuring, and iterating in production.

The engineering culture is AI-native: engineers solve customer problems end-to-end, while AI agents support coding and repeatable tasks. The role requires product thinking, autonomy, curiosity, and a focus on measurable customer and business impact.

Responsibilities

• Own product features end-to-end, from ideation with Product and Design to production delivery, measurement, and iteration.
• Build features supporting multi-dimensional personalization, A/B experimentation, and analytics.
• Make technical decisions with a product-oriented understanding of the underlying customer and business goals.
• Develop and maintain a high-quality, high-performance Go codebase.
• Mentor colleagues and improve engineering best practices.
• Influence team vision and long-term goals, including decisions about what to build.
• Conduct research and development spikes when the path forward is unclear.
• Collaborate with engineering, product, and design in a cross-functional team.

Requirements

• At least 5 years of backend development experience.
• Strong skills in Python, PHP, Ruby, or a similar language, with readiness to work in Go daily.
• Experience in a product company, ideally a startup or scale-up environment characterized by speed, ambiguity, and ownership.
• B2C experience is strongly preferred, particularly experience building products for millions of users.
• Solid system design skills and the ability to select appropriate architectural patterns.
• Experience with SQL databases such as MySQL and PostgreSQL.
• Experience with NoSQL technologies such as Redis and Cassandra.
• Experience with Kafka or similar event-driven systems.
• Interest in building simple, easy-to-use APIs.
• Collaborative approach to discussing, rethinking, and redesigning ideas.

Bonus Points

• Experience building an independent product, startup, side project, or application used by real users.
• Experience with Kubernetes and microservice architecture.
• A record of shipping experiments, testing hypotheses, and measuring impact.
• Comfort working with AI-native development tools such as Claude Code, OpenAI Codex, and Cursor.

Technologies

• Backend: Go, MySQL, Kafka, Docker, Kubernetes, AWS, Redis.
• Frontend: Next.js, React, TypeScript, GraphQL, Tailwind CSS, Cloudflare Workers.
• iOS: SwiftUI, Xcode, Combine, SPM, MVVM.
• Android: Kotlin, Hilt, Coroutines, Jetpack Compose, MVVM.
• AI tools: Claude Code, OpenAI Codex, OpenCode, Cursor.

Benefits

• Online and in-person training, Coursera and Skillshare access, mentorship, and internal career opportunities.
• Extra vacation days, sick leave, special occasion leave, and parenting leave.
• Premium private health insurance in Poland and Lithuania.
• Subscriptions to Calm, Headspace, and Mindletic, plus mental health and resilience programs.
• Fitness benefits including in-house gyms, Multisport and Urban Sport cards, online workouts, and physical well-being support.
• Company workations and the option to work from different locations.
• Gifts for birthdays, work anniversaries, weddings, and new family members.
• Summer camps for children and flexible arrangements for parents.
• Team-building activities and company events.
• Access to the Vilnius headquarters and its workspace facilities.