Senior Software Engineer (Android) - Service Agreement

FlixTrain is hiring a Senior Software Engineer (Android) - Service Agreement in Warsaw, Poland. Level rates it ; you can apply on FlixTrain.

Level's read on this job

Level rates this software engineer role Little AI ●○○○: aI is not part of the work.
The posting mentions Kotlin, Jetpack Compose and Android among its tools and skills.
Level classes it as a senior role.
FlixTrain has 124 other open roles on Level.
Posted within the past two weeks.

AI in this role

Build, optimize, and scale Android applications to enhance the passenger journey and drive mobile development excellence.

kotlinjetpack-composeandroidgitci-cd

android-developmentmobile-architectureui-optimizationperformance-tuningtesting

Rate: 135 – 170 PLN/hour (B2B)

We are looking for an experienced Senior Software Engineer to join Flix on a freelance/service agreement basis (B2B contract). This is a contractor engagement for a seasoned professional who doesn’t just write code but thinks about the entire mobile ecosystem, including performance, quality, scalability, UX, and testing.

Scope of Services

Bring expertise in building high-quality, scalable, and user-friendly Android applications to enhance the Flix passenger journey — optimizing key features such as post-booking and home page experiences, while incorporating innovative solutions that drive mobile development excellence.

About the Engagement

Design, develop, and maintain high-quality Android applications with a focus on scalability, performance, and user experience.
Support closely iOS, Backend, and feature teams to align on feature specifications and ensure seamless cross-platform integration.
Drive technical improvements across the entire codebase, including architecture enhancements and codebase modernization.
Enhance app performance and user experience through UI optimizations, accessibility compliance, and improvements in battery usage, memory management, and load times.
Leverage analytics & metrics to make data-driven decisions, optimizing performance and engagement based on user behavior and app health.
Write clean, maintainable, high quality and testable code, ensuring high test coverage through unit, integration, and UI tests to guarantee reliability.
Actively contribute to improving CI/CD pipelines, app stability, and release processes, driving faster delivery and higher productivity.
Maintain clear, up-to-date technical documentation, including API specs, architectural decisions, and code comments, fostering transparency and knowledge sharing within the stakeholders.

About You

6+ years of Android development experience with a proven track record of building high-quality, user-facing Android apps.
Strong expertise in Kotlin (Jetpack Compose, MVVM, Coroutines), with a deep understanding of Android architecture and best practices.
Hands-on experience with performance optimizations, background services, memory management, and smooth user interactions (UI, animations).
Experience with testing (unit, integration, UI testing) and a strong commitment to writing testable, maintainable code.
Ability to drive technical strategy, ensuring high standards in code quality, performance, and scalability.
Understanding of SOLID principles and software architecture patterns.
Experience working with CI/CD pipelines and automated deployment systems (GitLab, Fastlane, Docker).
Experience with Firebase SDK, including Firebase Analytics, Remote Config, and Crashlytics.
Customer-centric approach with a focus on delivering great user experiences.

Cooperation model

Cooperation based on a service agreement (B2B/freelance contract), not an employment contract.
You will operate as an independent contractor, responsible for delivering agreed services and submitting invoices
Location: open for contractors based in Poland

How we rate this

Senior Software Engineer (Android) - Service Agreement at FlixTrain rates 0 out of 100 for how much of the daily work is AI. That makes it Little AI (AI Level 1 of 4). The level is about AI in the job, not seniority.

Classification

Little AI. AI is not part of the work.

●●●● Builds AI80 to 100
●●●○ Works on AI60 to 79
●●○○ Uses AI40 to 59
●○○○ Little AI0 to 39

Levels come from how often the tools, models and workflows of the role are named in the posting itself. Read the description and count the AI tools, models and workflows it names.

Key facts

Senior Software Engineer (Android) - Service Agreement is an open job at FlixTrain.
Level rates this role AI Level 1 of 4: Little AI.
The role is based in Warsaw.
The job was posted on October 21, 2026.
Seniority: senior.
Applications are handled by FlixTrain. Apply on FlixTrain

Prepare for this job

Built from this posting and from similar jobs on Level.

Skills and AI tools this role asks for

Android DevelopmentMobile ArchitectureUI OptimizationPerformance TuningTestingKotlinJetpack ComposeAndroid

Also common in software engineer jobs at this level

Python Java AWS C++Kubernetes TypeScript

Pay

Typical software engineer job: $167k

This posting doesn't list pay. Use the typical software engineer figure when pay comes up. See software engineer jobs

Questions you could be asked

Tell me about a project where android development was part of your work. What did you do?
Tell me about a project where mobile architecture was part of your work. What did you do?
Tell me about a project where ui optimization was part of your work. What did you do?
Tell me about a project where performance tuning was part of your work. What did you do?
Tell me about a project where testing was part of your work. What did you do?

Adapt your resume

List these exact terms on your resume: Android Development, Mobile Architecture, UI Optimization, Performance Tuning, and Testing. An applicant tracking system matches the wording, not the idea.
Attach one line of real, concrete experience to at least one of them. A tool named with nothing behind it rarely survives a human read.

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