Senior Backend Engineer

BlueThrone; Warszawa; Remote; PLN 180,000 - 280,000; Full time

Job summary

BlueThrone is seeking a Senior Backend Engineer to design and build scalable backend systems across multiple products. You’ll operate across infrastructure, architecture, and product domains, shifting between contexts with ease to resolve production issues and improve systems.

You’ll work primarily in Go, with exposure to Node.js and Python as needed, and collaborate with product, frontend, data, and other engineers in a remote-first setup across time zones.

Qualifications

• 5+ years of backend engineering experience.
• Designed or significantly changed a backend system.
• Made architectural decisions and explained trade-offs.
• Worked with databases beyond an ORM.
• Operated and debugged services in production.
• Understood infrastructure and how it impacts systems.
• Took work from unclear problems to shipped results.
• Learnt new technology when needed.

Responsibilities

• Design, build, run, and improve backend systems across multiple products.
• Take problems from unclear starting points through architecture, implementation, deployment, and iteration.
• Investigate systems you didn’t build.
• Work with product, frontend, data, and other engineers.
• Improve existing systems rather than always rewriting.

Skills

Backend engineering

Go

Distributed systems

Docker

Kubernetes

Cloud infrastructure

Production troubleshooting

Architecture discussions

Tools

Docker

Kubernetes

Kafka

Job description

Build systems, not just services.
Work across products, not inside one codebase.
Own problems from first question to production.

The role

We run a portfolio of mobile products used by millions of people.

Our engineering team works across that portfolio.

You won't join a permanent team attached to one app. You might spend your first few weeks improving the backend of one product because that's where the biggest technical need is. A month later, you could be designing a service for another, helping resolve a production incident elsewhere, or improving infrastructure used across several products.

That's intentional.

We want engineers who can understand a system quickly, find the real problem, and move between different technical contexts without needing everything to stay familiar.

We're looking for a Senior Backend Engineer who combines depth in backend engineering with breadth across systems, infrastructure, architecture, and product.

Think T-shaped: deep in backend engineering, broad enough to understand the systems around it.

How engineering works here

There is not always a perfectly specified ticket waiting for you.

Usually, there is a problem.

A service is struggling under load. A database model no longer fits the product. A team needs to test something quickly. An API needs redesigning. Something breaks in production.

Your job is to understand the context, decide what engineering should do next, and build it.

That means asking questions beyond implementation:

What problem are we actually solving? What happens upstream and downstream? What breaks if usage grows 5x? What trade-off are we making? Does this need a new service at all?

We care more about how you reason about the whole system than how well you know one framework.

What you'll work with

Go is our backend standard.

Roughly 80–90% of our backend work is Go, with the rest mainly in Node.js and Python.

You don't need to have spent your whole career writing Go. You might come from Java, Kotlin, Python, Node.js, or another backend ecosystem.

What matters is that you can become productive in Go and don't treat one language as your professional identity.

You should also understand the infrastructure behind the code, including:

• relational databases, schema design, migrations, indexing, and query behaviour;
• distributed systems, message queues, and brokers such as Kafka;
• Docker and Kubernetes;
• cloud infrastructure and APIs;
• observability, performance, reliability, and failure modes.

What you'll actually do

You'll design, build, run, and improve backend systems across multiple products.

You'll take problems from an unclear starting point through architecture, implementation, deployment, and iteration.

You'll investigate systems you didn't build.

You'll work directly with product, frontend, data, and other engineers.

You'll improve existing systems instead of assuming everything needs a rewrite.

And when something breaks, you'll help solve it even if it wasn't part of your plan that morning.

Ownership means the whole thing

When we say ownership, we don't mean completing your assigned engineering tasks without reminders.

It's being able to take a problem, understand the context, speak to the right people, identify the unknowns, make the trade-offs visible, and get the solution into production.

Then check whether it worked.

There won't always be someone turning the problem into a checklist first.

You’ll probably thrive here if

You naturally zoom out before zooming in.

You can discuss architecture in the morning, debug a production issue in the afternoon, and work in an unfamiliar codebase the next day.

You care more about solving the problem than protecting your preferred stack.

You can make a sensible decision without having 100% of the information.

You ask questions about the product and user instead of treating requirements as fixed instructions.

You learn unfamiliar technology when the problem requires it.

You change your mind when new evidence makes your original approach wrong.

And when you notice a problem outside your current task, your first reaction isn't: “That's not mine.”

This probably won't work if

You want to spend the next 2 years inside one product, codebase, or narrowly defined area.

You need a detailed specification before you can start thinking about a problem.

You want architecture separated from implementation.

You prefer handing infrastructure, databases, deployments, or production problems to another team.

You strongly identify with one programming language and don't want to work outside it.

Frequent context changes drain you more than they interest you.

Or you measure seniority mainly by how little hands-on engineering you have to do.

None of those are bad ways to work.

They're just different from how engineering works here.

What we’re looking for

As a guide, this usually means 5+ years of backend engineering experience, but the number matters less than what you've owned.

You should be able to show examples where you:

• designed or significantly changed a backend system;
• made architectural decisions and explained the trade-offs;
• worked with databases beyond using an ORM;
• operated and debugged services in production;
• understood infrastructure rather than treating it as a black box;
• took work from an unclear problem to a shipped result;
• learned new technology when needed.

Production experience with Go is useful.

Strong backend experience in another language plus evidence that you learn new stacks quickly can work too.

How we work

We work across a portfolio of live products with real users and existing systems.

Some systems need scaling. Some need simplifying. Some need migrating. Some should be left alone.

Being able to tell the difference matters.

We're remote-first and work across countries and time zones.

We document decisions, communicate directly, and care about outcomes more than visible activity.

Priorities can change when new information appears. A production issue can become more important than yesterday's plan.

We expect people to understand the new context, adjust, and keep moving.

The mindset we value

Think in systems. Understand how the parts connect before optimising one of them.

Think about the product. The technically elegant solution isn't automatically the useful one.

Own the outcome. Don't stop at “my code works.”

Stay flexible. Your current project, technology, or priority isn't your territory.

Learn quickly. What you know matters. How fast you can understand what you don't know matters too.

Use judgment. Some problems deserve 3 days of investigation. Others need a good decision in 30 minutes.

Change your mind when the evidence changes.

One last thing

We're not hiring you for one app.

We're hiring you because we want someone who can become useful wherever the most important backend problem is.

If your favourite engineering question is “How does this whole thing actually work?”, we'll probably have plenty to talk about

Equal opportunities for everyone

To truly represent our vibrant and diverse BlueThrone community, we prioritize diversity and inclusion. We are committed to fostering an environment where everyone can do their best work. We strongly encourage applicants of all backgrounds. We consider all candidates regardless of age, ethnicity, religion, sex, sexual orientation, gender identity, family or parental status, national origin, veteran status, neurodiversity, or disability. If you need reasonable adjustments at any point in the application or interview process, please let us know.