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

Nord Security; Polska; On-site; PLN 180,000 - 260,000; Full time

Benefits offered by this job

Training & mentorship

Extra vacation days

Healthcare in Poland and Lithuania

Mindfulness trainings

In-house gyms & sport cards

Workation opportunities

Job summary

Saily is seeking a seasoned backend engineer to ship real-world features for travelers. You will own features end-to-end from idea to production, with autonomy and a product-driven mindset. Go is central, but you’ll work with Python, PHP, and various data systems to move metrics.

You’ll join an AI-native engineering culture that emphasizes curiosity, cross-functional collaboration, and scalable architectures to support 200+ destinations and millions of users.

Qualifications

• 5+ years of backend development experience.
• Strong skills in Python, PHP, Ruby, or similar; daily Go usage.
• Product company experience, ideally startup or scale-up.
• B2C experience for millions of users.
• Solid system design skills.
• Experience with SQL and NoSQL.
• Experience with Kafka or similar event-driven systems.
• Passion for building APIs that are easy to use and understand.

Responsibilities

• Own product features end-to-end: shaping the idea with Product and Design to shipping, measuring, and iterating.
• Build features supporting multi-dimensional personalization, A/B experimentation, and analytics.
• Make technical decisions with a product lens — you’ll know the 'why' behind every 'what'
• Develop and maintain a high-quality, high-performance codebase in Go.
• Mentor colleagues and raise the bar on engineering best practices.
• Influence your team's vision and long-range goals — your opinion on what we build matters as much as how
• Run R&D spikes when the path forward isn't obvious.
• Collaborate across engineering, product, and design in a cross-functional team.

Skills

Backend development

Go

Python

PHP

Ruby

SQL (MySQL, PostgreSQL)

NoSQL (Redis, Cassandra)

Kafka

API Design

Collaboration

Tools

Go

MySQL

Kafka

Docker

Kubernetes

AWS

Redis

PostgreSQL

GraphQL

TypeScript

React

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. Millions of paying customers trust us, and hundreds of thousands of travelers browse Saily at any given moment.
We're not looking for someone to close tickets. We're looking for a builder — someone who has shipped products real people use, felt the pain of a 2 AM incident on something they care about, and gets a kick out of seeing a metric move because of something they built.

Our Culture: AI-native Product Engineering

• The Engineer is the builder — responsible for solving customer problems end-to-end, from idea to production

• AI Agents are the enablers — they write most of the code and handle repeatable tasks, so you maximize your impact

• Everyone makes Saily more effective — you suggest what to delegate to agents, then implement the changes

• Curiosity, learning, and sharing are everyone's job

• The customer — a traveler on a comfortable, connected, hassle-free journey — never leaves our focus

We value growth over comfort, contribution over hierarchy, and impact over process. We give sharp people context, autonomy, and AI as their multiplier — and expect their best work in return.
Main Responsibilities

• Own product features end-to-end: from shaping the idea with Product and Design to shipping, measuring, and iterating

• Build features supporting multi-dimensional personalization, A/B experimentation, and analytics

• Make technical decisions with a product lens — you'll know the "why" behind every "what"

• Develop and maintain a high-quality, high-performance codebase in Go

• Mentor colleagues and raise the bar on engineering best practices

• Influence your team's vision and long-range goals — your opinion on what we build matters as much as how

• Run R&D spikes when the path forward isn't obvious

• Collaborate across engineering, product, and design in a cross-functional team

Requirements

• 5+ years of backend development experience, with strong skills in Python, PHP, Ruby, or similar — and readiness to work in Go daily

• Product company experience, ideally startup or scale-up — you've worked where speed, ambiguity, and ownership are the norm, not the exception

• B2C experience strongly preferred — you understand what it means to build for millions of users you'll never meet, where small UX details and performance directly hit revenue and retention

• Solid system design skills: you know which patterns to use, when, and why

• Experience with SQL (MySQL, PostgreSQL) and NoSQL (Redis, Cassandra) solutions

• Experience with Kafka or similar event-driven systems

• Passion for building APIs that are easy to use and simple to understand

• A collaborative mindset — you love discussing, rethinking, and redesigning ideas toward shared success

Bonus Points

• You've built your own product — a side project, a startup (successful or not), an indie app, anything you took from zero to real users. We find that people who've carried a product themselves think differently: they obsess over the user, they ship, they own outcomes. If that's you, tell us about it — it matters more to us than logos on your CV

• Experience with K8s and microservice architecture

• A track record of experiments shipped, hypotheses tested, and impact measured (not just features delivered)

• Comfort working AI-native: Claude Code, Codex, Cursor — you see AI as a multiplier, not a threat

Tools You Will Use

• 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

What We Offer

• Sharpen your edge: training, mentorship, and room to grow — always.

• Take the time you need: extra vacation days, sick days, and time off when life calls.

• Get premium healthcare: private health insurance in Lithuania and Poland — fully covered.

• Protect your peace: enjoy free subscriptions to Calm, Headspace, and Mindletic, and our own resilience and mindfulness trainings.

• Own your fitness: in-house gyms, sport cards, online workouts, and personal guidance — on us.

• Pack your bags for workation: experience our company-wide