Application session / Alex Kostyniuk

I build features across the stack. I care a lot about the UI, but I'm just as comfortable following the work into backend services or the data behind them when that's what the feature needs.

Full-stack engineer · Frontend / Backend · Stockholm

Alex Kostyniuk

Now building

End-to-end features

React · Backend · APIs · Data

Why we're a good fit

Why Spotify should hire me

I can ship
I build features end to end—from the React interface and design system to backend services and the data behind them.
I care about the details
I care deeply about UI and UX. I want the interaction to feel obvious, fast, and polished, not merely work.
I think beyond the ticket
I start with the customer and business problem, then work with Design and engineering to find the right feature to build.
I use AI well
I introduced agentic workflows at my current company and use them to move faster while keeping judgment, testing, and review in the loop.
I can go deep
I am as happy discussing a small interaction detail as I am tracing a slow query or changing the architecture behind a workflow.
I care about the team
I lead engineers today. I still build, but I get just as much satisfaction from helping the people around me do their best work.

Why I want to join Spotify

A product people choose every day
Spotify is the kind of product I want to build: something people open because they want to, and where a small improvement can matter at enormous scale.
The whole stack matters
The simple experience hides difficult work across product, UI, data, experimentation, and distributed systems. That range is exactly what I enjoy.

How I work.

I start with either a problem to solve or a business idea. I shape it around customer needs and technical realities, and look for a solution that can serve many customers instead of just one. Once the core is clear, I work with Design team on the experience, break it down into a focused story, and leave it ready for a developer or me to build.

How I develop features

  1. 01

    Start with an agent

    I always work with an agent. For bigger features or bugs that aren't obvious at first, I use specific skills to help it focus. For smaller tasks, I explain what needs doing and jump in.

  2. 02

    Scope the solution

    When the work needs a plan, I turn it into a detailed spec, including edge cases and what done looks like.

  3. 03

    Implement with agents

    Once the task is clear, I let one or more agents build the feature.

  4. 04

    Create feedback loops

    Browser Use, types, and tests help the agents see what they built and catch their own mistakes.

  5. 05

    Check manually

    I still open the feature and use it myself, from start to finish.

  6. 06

    Run an agent review

    I ask fresh agents to review the work and catch anything the first ones missed.

  7. 07

    Review the code

    Then I read the diff myself and fix whatever is left.

  8. 08

    Babysit the PR

    Finally, an agent watches CI and review comments until the PR is ready to merge.

Outcome

The result is a feature that has been planned, built, checked, and reviewed from a few different angles—usually in much less time.

Let's build something people want to come back to.

Spotify × Alex

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