Senior Software Engineer - Data Engineering (m/f/d)
Klar
Software Engineering, Data Science
Posted on Oct 22, 2025
Senior Software Engineer - Data Engineering (m/f/d)
About Klar
Klar is the Data Operating System for growing eCommerce companies - no more spreadsheets. We integrate with all their data sources to provide them with detailed insights on how to accelerate growth and increase profitability.
We deeply empathise with the struggles of our customers - after having worked most of the last 10 years in e-commerce companies, we know their pain and built Klar to help.
We work with over 1,000 leading eCom brands like Sunday Natural, Loop Earplugs, Holy, Maniko, Armed Angels and hundreds more use Klar to make better decisions every day.
Our guiding principle is Do Work You Are Proud Of - we emphasize long-term quality over short-term results.
If you want to learn more about Klar, click here.
The Klar tech stack:
We are a 100% Open Source shop and make use of industry-leading tools & technologies.
Frontend:
TypeScript
React & Redux
MUI ( Formerly material-ui )
Backend
Backend for Frontend API Layer written using TypeScript & NestJS
Backend Core is an implementation of clean architecture with event sourcing
Data, Integrations & Query layer
Various applications written using Python 3
Kafka & Clickhouse
Prefect 2 & Luigi workflow management
Infrastructure
Kubernetes, Flux CD Git Ops
CI using Github Actions
Cloudflare Pages
About the Senior Software Engineer - Data Engineering role
As a Senior Data Engineer at Klar, you will be a key driver in the evolution of our data platform. You will be responsible for architecting, building, and scaling the systems that ingest, process, and serve petabytes of data, providing the core value our customers rely on. Beyond just maintaining pipelines, you will take ownership of major components of our data infrastructure, mentor other engineers, and set the technical direction for how we handle data at scale.
We leverage Prefect for our core extraction workflow, Clickhouse as our primary data store, and a custom Python application for our Query Layer, which also performs ELT. You will not only contribute to these systems but also help define their future. We are on the road to Continuous Delivery and you will play a vital role in making that a reality for our data platform.
Read more about engineering at Klar:
What you’ll do:
Design & Build: Architect, implement, and maintain scalable, reliable, and performant data pipelines and systems.
Lead & Mentor: Take technical ownership of complex projects, guide technical decisions, and mentor other engineers on the team, fostering a culture of excellence.
Optimise & Scale: Identify and resolve performance bottlenecks in our data processing, storage, and query layers to ensure our platform can handle ever-increasing data volumes.
Collaborate: Work closely with backend, frontend, and product teams to understand data requirements and deliver robust solutions.
Innovate: Research and champion new technologies, architectural patterns, and best practices to keep our data platform modern and effective.
Requirements:
Strong Python Proficiency: Proven, hands-on experience using modern Python (3.x) to build and maintain data-intensive applications.
Advanced SQL: Deep, practical knowledge of SQL and data modeling, with experience in query optimization and working with analytical databases.
System Design: Proven experience designing, building, and operating large-scale data processing systems and pipelines in a production environment.
Big Data Expertise: You love dealing with big data and have a demonstrable track record of wrangling huge datasets efficiently and reliably.
Quality-Driven: You pride yourself in the quality of your work, producing code that is well-tested, concise, readable, and maintainable.
DevOps Mindset: You are comfortable setting up and maintaining a modern build-pipeline using tools like Github Actions, Docker, and Kubernetes.
Strong Communicator: You can articulate complex technical concepts clearly and are keen on expanding your technical horizon, always open to challenging the status-quo.
Previous experience with Kafka, Clickhouse, Prefect, or similar technologies (e.g., Airflow, Spark, Flink) is a significant advantage.
Our recruiting process:
Application Review:
We review your application. In order to make the process as efficient as possible, please make sure that all the info on your CV is up to date and that you've included all relevant information about yourself and your professional experience in your documents.
If we come to the conclusion that you could be a good fit for the position you'll receive an invitation for Step 2 (the first interview).
First Interview
The first interview only takes between 30 and 45 minutes and the goal is to get to know each other better. We'll talk about your motivation for joining Klar as well as your professional experience and also give you the opportunity to get to know us better and learn everything you want to know about Klar.
If both parties like what they hear and we proceed to step no. 3 we'll invite you to solve a coding challenge.
Coding Challenge
We've developed a few interesting challenges that are very similar to the real-world tasks you could face at Klar. You'll get an adequate amount of time to complete the challenge and submit your code back to us.
We'll swiftly review your solution and if you've managed to convince us with the solution and your approach you'll receive an invitation for the second interview.
Second Interview
Based on your professional experience and your fields of expertise we'll prepare a bunch of questions to really get to know your level of proficiency. That can be anything from describing an interesting project you've worked on to talking about a hypothetical technical problem you're facing and how your approach to solving it would look like. We're trying to keep this step as fair and unbiased as possible and no, ... you don't have to write code to invert a binary tree on a white-board.
Like in the first interview there will be also time for you to ask questions about our tech stack, and what it's like to work with us.
Meet the Co-Founders
We value strong fit and alignment within our team. This gives you and us a chance for a final check.
Offer
We'll personally contact you to discuss the terms of the employment with you.
