Senior Software Developer (all genders) — Scalable Mobility Platform

About us

CheckCars24 GmbH is a modern, fast-growing e-commerce company based in Berlin. Our mission is to reinvent the way people buy cars - making the process simpler, more transparent, and more customer-friendly than ever before. With a stock of over 20,000 immediately available new and nearly-new condition vehicles across more than 33 brands, we offer attractive deals and a seamless buying experience. To support our growth, we are looking for motivated people who want to help shape the future of online car purchasing with us.

Checkcars24 is looking for you as an expert Senior Software Developer (C# / .NET).

We are looking for a Senior Software Developer (C# / .NET) to design, build, and evolve scalable cloud-native microservices on Microsoft Azure. You will work on a high-impact platform that manages the full lifecycle of automotive sales leads - from multi-channel ingestion (web, HubSpot, Meta, TikTok) through a complex 10-stage CRM workflow to customer feedback and analytics.

This role involves working on systems with real financial implications, strict SLA requirements, and multiple external integrations. You will take ownership of core services, set engineering standards, and mentor other developers.

Your mission

Design and extend a complex 10-stage CRM workflow engine with state transitions and audit trails

Build and maintain .NET 7+/8 microservices on Azure

Develop and secure REST APIs (OAuth2, JWT, webhook HMAC validation)

Integrate external systems (HubSpot, Microsoft Graph, Meta, TikTok, TrustPilot)

Implement resilient background processing (queues, retries, idempotency, scheduling)

Work with Azure services (Blob Storage, Queue Storage, Cosmos DB, App Service, Key Vault)

Ensure system reliability using observability, logging, and performance monitoring

Maintain CI/CD pipelines and testing standards

Your profile

Requirements

Strong experience with C# / .NET 7+ (async/await, DI, ASP.NET Core)

Hands-on experience with Azure cloud services

Strong understanding of REST API design and security

Experience with distributed systems (queues, retries, idempotency, concurrency)

Background in clean architecture and domain-driven design

Experience with testing (xUnit, Moq) and CI/CD pipelines

Nice to have

CRM integrations (HubSpot preferred)

Meta / TikTok lead ad APIs

Microsoft Graph API

TrustPilot or similar review platforms

OAuth2 server experience (e.g. OpenIddict)

Soft Skills

Ability to model complex business workflows into reliable state machines

Strong ownership of production systems and incident troubleshooting

Clear communication in English and German

Willingness to challenge technical risks and improve system design

Tech Stack

NET 8, ASP.NET Core, Azure (Blob/Queue/Cosmos/Key Vault/App Service), Microsoft Graph, HubSpot API, Meta & TikTok APIs, TrustPilot API, OpenIddict, Polly, xUnit, Azure DevOps, Swagger/OpenAPI

Why us?

What you can expect

Join a company where technology is becoming the core driver of the business. You will work on products that directly impact thousands of real customer interactions, building systems that solve meaningful, real-world problems at scale. Instead of maintaining legacy software or acting as an external service provider, you will own your products end-to-end and continuously evolve them.

Shape Systems, Not just Features

You will contribute to the architecture and development of modern, cloud-native platforms built on .NET and Azure. From distributed workflows and AI-supported processes to deep integrations with leading external providers, you will work on systems that are business-critical, highly reliable, and continuously evolving.

Grow with a Company in Transformation

We are in a phase of rapid growth and strong technological expansion. This creates real opportunities to influence architecture decisions, define engineering standards, and take ownership of initiatives that visibly shape the company’s future direction.

Work with Modern Technologies

Our engineering culture embraces modern software practices, cloud infrastructure, automation, AI-driven solutions, and scalable system design. You will have the freedom to apply new technologies where they create real value, rather than being constrained by legacy systems.

Learn from a Strong Technology Network

You will collaborate with partners at the forefront of AI and emerging technologies, gaining exposure to innovative engineering approaches and international technology ecosystems.

Flexible and Sustainable Working

Flexible working hours

Hybrid working model with one office day per week

A stable, long-term role in a growing, technology-driven company

If you are motivated by building impactful products, influencing technical direction, and scaling modern digital mobility solutions, this is the right environment for you.