Backend Engineer - Senior - Go - Saily

Details

Saily is building a mobile data product that helps travelers stay connected without roaming fees or physical SIM cards. The product provides secure mobile data in more than 200 destinations and serves millions of paying customers.

Saily fosters an AI-native Product Engineering culture in which engineers solve customer problems end to end, while AI agents help write code and handle repeatable tasks. Engineers are expected to contribute to product improvement, share knowledge, and focus on customer outcomes.

Responsibilities

• Enhance the Saily product by developing and maintaining new features.
• Create features supporting multi-dimensional personalization, A/B experimentation, and analytics.
• Develop and maintain a high-quality codebase.
• Continuously improve code quality and performance.
• Mentor colleagues on development best practices and provide technical guidance.
• Influence the overall vision and long-term goals of the team.
• Perform research and development operations when required.
• Work as part of a cross-functional team and support smooth communication between team members.
• Collaborate with engineering, product, and design professionals from other teams.

This position requires office attendance three times per week.

Requirements

• 4+ years of product experience, preferably in a startup or scaleup environment.
• Proven experience working with Go.
• Strong system design knowledge, including understanding which patterns to use, when, and why.
• Experience with Kubernetes and microservice architecture is a plus.
• Experience with SQL solutions such as MySQL and PostgreSQL.
• Experience with NoSQL solutions such as Cassandra and Redis.
• Experience with Kafka.
• Passion for building APIs that are easy to use and simple to understand.
• Strong product mindset, with a focus on problems, outcomes, and impact rather than only tickets or tasks.
• Curiosity about AI and enthusiasm for working with AI agents.

Technologies

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

Benefits

• Online and in-person training, access to Coursera and Skillshare, mentorship, and internal career opportunities.
• Extra vacation days that increase with tenure, additional sick leave, special-occasion and parenting days.
• Premium private health insurance available in Lithuania and Poland.
• Subscriptions to Calm, Headspace, and Mindletic, along with resilience and mindfulness training and mental health events.
• In-house gyms, Multisport and Urban Sport cards, online workouts, group mobility sessions, fitness guidance, and individual consultations.
• Company workation opportunities.
• The ability to work from different locations.
• Gifts for birthdays, work anniversaries, weddings, and new family members.
• Summer camps for children and flexibility for parents.
• Team-building activities and company events.
• Access to the Vilnius headquarters, including silent rooms, gyms, a game room, music room, and coffee bar.