Backend Engineer | Mid - Senior | Go | Saily

Saily; Warszawa; Hybrid; PLN 320,000 - 460,000; Full time

Benefits offered by this job

Private health insurance

Multisport card for fitness

Mental health resources & wellness

Company events & team-building

Work from anywhere

Job summary

Saily is building a cutting-edge product engineering culture in the travel data space. The company prioritizes AI-native approaches, cross‑functional collaboration, and an impact‑driven mindset to deliver fast, secure mobile data globally.

The Senior Product Engineer role focuses on extending features, designing scalable APIs, and mentoring peers within a hybrid work setup. You’ll collaborate with engineering, product, and design teams to propel the product forward.

Qualifications

• 4+ years of product experience, preferably in a startup/scaleup environment.
• Proven experience working with Go.
• System design is familiar; know what patterns to use and when.
• Experience with Kubernetes and microservice architecture is a plus.
• Experience with SQL (MySQL, PostgreSQL) and NoSQL (Cassandra, Redis) technologies.
• Experience with Kafka.
• Passionate about building APIs that are easy to use and understand.
• Strong product mindset: focus on problems, outcomes, and impact.
• Curious about AI and excited to work with agents.

Responsibilities

• Enhancing the Saily product by developing and maintaining new features.
• Create features to support layers of multi-dimensional personalization, A/B experimentation, and analytics.
• Develop and maintain a high-quality codebase.
• Seek to improve code and performance constantly.
• Mentor colleagues on development best practices & provide technical guidance.
• Exercise influence on the overall vision and long‑range goals of your team.
• Perform R&D operations whenever required.
• Work as part of a cross‑functional team and help to ensure smooth communication between all team members.
• Collaborate with engineering, product, and design professionals from other teams.

Skills

Strong API mindset

Product-focused

Cross-functional collaboration

Curiosity about AI

Tools

Go

Kubernetes

Kafka

SQL (MySQL, PostgreSQL)

NoSQL (Cassandra, Redis)

REST/GraphQL APIs

Front-end tech (Next.js, React.js, TypeScript)

Job description

At Saily, we’re removing the hassle of staying connected while traveling — no roaming fees, no plastic SIM cards, just lightning-fast, secure mobile data in 200+ destinations. Saily has millions of paying customers and hundreds of thousands of travelers browsing through Saily at any given moment.

To build the best product for our customers, we foster AI-native Product Engineering culture, where:

• The Engineer is the builder, who is responsible for solving customer problems end-to-end (idea to production)
• AI Agents are the enablers who write most of the code and solve repeatable tasks to help the Engineers maximize their impact
• Everyone contributes to making Saily effective by suggesting new areas for improvement, delegating them to agents, and then implementing the changes
• Curiosity, learning and sharing are everyone's responsibility
• Customer, having a comfortable, connected, hassle-free journey is never lost from the focus

We value growth over comfort, contribution over hierarchy, and impact over process. At Saily, we believe in giving sharp people context, autonomy, and AI as their multiplier to allow them to just do their best work.

Main Responsibilities

• Enhancing the Saily product by developing and maintaining new features.
• Create features to support layers of multi-dimensional personalization, A/B experimentation, and analytics.
• Develop and maintain a high-quality codebase.
• Seek to improve code and performance constantly.
• Mentor colleagues on development best practices & provide technical guidance.
• Exercise influence on the overall vision and long‑range goals of your team.
• Perform R&D operations whenever required.
• Work as part of a cross‑functional team and help to ensure smooth communication between all team members.
• Collaborate with engineering, product, and design professionals from other teams.

This is a hybrid position requiring office attendance 3 times a week - Monday, Wednesday, Friday.

Core Requirements

• 4+ years of product experience, preferably in a startup/scaleup environment
• Proven experience working with Go
• System design is nothing new to you, and you know what patterns to use, when, and why
• Previous experience in working with K8s and microservice architecture is a plus
• Previous experience with SQL (MySQL, PostgreSQL) and NoSQL (Cassandra, Redis) solutions
• Previous experience with Kafka
• Passionate about building APIs that are easy to use and simple to understand
• Strong product mindset: focus on problems, outcomes, and impact—not just tickets or tasks
• You are curious about AI and excited to work with agents.

Tools You Will Use

• Frontend: Next.js, React.js, TypeScript, GraphQL, Tailwind CSS, Cloudflare Workers
• AI tools: Claude Code, OpenAI Codex, OpenCode, Cursor with Composer

Salary range

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What We Offer

Innovate with industry leaders

Work alongside global experts to build world‑leading cybersecurity tools, impacting millions of users around the world.

Learn & grow

Boost your skills via our extensive training programs (online and offline) & other resources. Benefit from mentorship and career‑switch opportunities to grow within the company.

Work from anywhere

Recharge with a change of scenery – choose work from any location when you feel a need to power your creativity and drive.

Physical well‑being

Fuel your active lifestyle with online workouts led by our Physical Well‑Being experts. Unlock a variety of sports and wellness facilities, like gyms, swimming pools, and fitness classes, with the Multisport card.

Mental & emotional health

Nurture your mind with free psychologist consultations, dedicated mental health events, and premium access to top‑rated wellness apps like Calm, Headspace, and Mindletic.

Receive private health insurance giving you peace of mind for your health needs.

Joyful moments – special treats

Celebrate life’s big moments with special gifts from us on your birthday, anniversary, and other major events, such as weddings or the arrival of a new family member.

Company events & team‑building

Experience iconic Nord Security celebrations, team‑buildings, and knowledge‑sharing events, nurturing bonds that fuel our success.

Workation

Embark on a legendary company getaway abroad, filled with exciting activities, live concerts, engaging workshops, and epic time together.