Senior Fullstack Software Engineer (Python/Java) - Service Agreement
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Before you apply
LocationBerlin, Warsaw
Also inPoland
Typecontract
SenioritySenior
Experience5+ yrs
DepartmentIT & Engineering
Company size1,001–5,000 people
PostedOct 26, 2026 · 1w ago
Verified live16h ago
At a glanceSummarised by Seekless from the posting.
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 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
Skills
Python
JavaScript
TypeScript
Java
flask
FastAPI
Node.js
React
Spring Boot
AWS
Azure
Terraform
Serverless
Elasticsearch
Snowflake
Kafka
Datadog
Kibana
Rate: 135 – 170 PLN/hour (B2B)
About the role
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
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Languages & Frameworks: Python, JavaScript, TypeScript, Java, flask, FastAPI, Node.js, React, Spring Boot.
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Cloud Providers and IaC: AWS, Azure, Terraform, Serverless.
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Data Layer: Elasticsearch, Snowflake
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Streaming and Messaging Layer: Kafka.
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Observability: Datadog, Kibana.
About the Engagement
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Deliver solutions for a defined portfolio of products, contributing to business objectives.
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Design and develop user-focused solutions tailored to product requirements and user needs.
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Apply Agile methodologies to organize and execute the development process.
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Develop and enhance products using modern technology stacks.
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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