Backend Engineer – Senior – Go – Saily

📍 Poland

PLN 288,000-400,800 per year

SENIOR

✅ Hybrid

Tech Stack
Tag name is followed by "@" symbol and proficiency level value. About proficiency levels:

1-2 — basic awareness. Minimal hands-on experience, and a rudimentary understanding of the technology's purpose;

3-6 — daily use. Comfortable and regular usage, capable of handling common tasks and challenges related to the technology;

7-9 — you are an expert, you can teach others, you know all the pitfalls and tricks;

10 — exceptional knowledge, comprehensive understanding, and adeptness in all aspects of the technology, including advanced problem-solving. Think twice before claiming or demanding such level.

AI @ 6 API @ 4 AWS Cassandra @ 4 Experimentation Go @ 6 Java @ 6 Kafka @ 4 Kotlin @ 6 Kubernetes @ 1 Microservices MySQL @ 4 NoSQL @ 4 PHP @ 6 PostgreSQL @ 4 Python @ 6 Redis @ 4 SQL @ 4

Details

Saily is building a sophisticated new eSIM product to provide secure mobile data in more than 200 destinations. The team follows an AI-native Product Engineering culture in which engineers solve customer problems end-to-end, while AI agents support coding, analysis, testing, and other repeatable tasks.

Responsibilities

Build a completely new sophisticated microservices system for the new eSIM product.
Create features supporting multidimensional 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-range goals of the team.
Perform research and development operations when required.
Use AI agents for specifications, coding, analysis, testing, and iteration.
Work as part of a cross-functional team and help ensure smooth communication between team members.
Collaborate with engineering, product, and design professionals from other teams.

Requirements

4+ years of experience with Go, or experience with a backend language such as PHP, Python, C#/.NET, Java, or Kotlin.
Strong system design experience, including knowledge of which patterns to use and when.
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.

Tools and Technologies

Go
MySQL
Kafka
Kubernetes
AWS
Redis
AI tools such as Copilot and Cursor

Benefits

Online and in-person training, access to Coursera and Skillshare, mentorship, and internal career opportunities.
Extra vacation days, additional sick leave, special-occasion and parenting leave.
Premium private health insurance in Lithuania and Poland.
Free subscriptions to Calm, Headspace, and Mindletic, plus resilience and mindfulness training and mental health events.
In-house gyms, Multisport and Urban Sport cards, online workouts, and physical well-being support.
Company workations abroad.
The ability to work from different locations.
Gifts for birthdays, work anniversaries, weddings, and new family members.
Summer camps for children and flexible working arrangements for parents.
Team-building activities and company events.
Access to the Vilnius headquarters, including silent rooms, gyms, a game room, a music room, and a coffee bar.