Senior Fullstack Software Engineer (Python/Java) - Service Agreement

FlixTrain is hiring a Senior Fullstack Software Engineer (Python/Java) - Service Agreement for a remote role open to applicants in 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.
This is listed as a remote role.
The posting mentions Python, JavaScript and TypeScript among its tools and skills.
FlixTrain has 124 other open roles on Level.
Posted within the past week.

AI in this role

Senior Fullstack Software Engineer contractor needed to develop contact center applications and agent-facing interfaces using Python and Java.

pythonjavascripttypescriptjavaflaskfastapinode-jsreactspring-bootawsazureterraform+4

fullstack-developmentsystem-designapiagile

Rate: 135 – 170 PLN/hour (B2B)

We are looking for an experienced Software Engineer to join Flix on a freelance/service agreement basis (B2B contract). This is a contractor engagement for a seasoned professional with a full-stack mindset.

Scope of Services

Developing Flix’s contact center applications, with a focus on scalable agent-facing interfaces and automation. The role will involve extensive discovery to identify the most efficient and effective workflows.

Our tech stack

Languages & Frameworks: Python, JavaScript, TypeScript, Java, flask, FastAPI, Node.js, React, Spring Boot.
Cloud Providers and IaC: AWS, Azure, Terraform, Serverless.
Data Layer: Elasticsearch, Snowflake
Streaming and Messaging Layer: Kafka.
Observability: Datadog, Kibana.

About the Engagement

Deliver solutions for a defined portfolio of products, contributing to business objectives.
Design and develop user-focused solutions tailored to product requirements and user needs.
Apply Agile methodologies to organize and execute the development process.
Develop and enhance products using modern technology stacks.
Make technical decisions within the scope of services provided, promoting technical excellence and consistency across solutions.

About You

Minimum 5 years of professional experience in full-stack development, with a focus on architecture, system design, and legacy product migration.
Extensive experience with Python and its ecosystem for the development of new products.
Solid knowledge of Java for the maintenance and further development of existing products.
Strong focus on quality assurance practices and technical standards throughout the product development lifecycle.
Hands-on with automated testing and experience with different test runners.
Comfortable with Agile methodologies in planning and executing development work.

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 Fullstack Software Engineer (Python/Java) - 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 Fullstack Software Engineer (Python/Java) - 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 and is marked remote.
The job was posted on October 26, 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

Fullstack DevelopmentSystem DesignAPIAgilePythonJavaScriptTypeScriptJava

Also common in software engineer jobs at this level

C++Kubernetes Docker C#Google Cloud Rust

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 fullstack development was part of your work. What did you do?
Tell me about a project where system design was part of your work. What did you do?
Tell me about a project where api was part of your work. What did you do?
Tell me about a project where agile was part of your work. What did you do?
Walk me through how you've used Python in your day-to-day work.

Adapt your resume

List these exact terms on your resume: Fullstack Development, System Design, API, Agile, and Python. 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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