Key Engineer (Staff / Principal Level) – Backend, Infrastructure & IoT

Key Engineer (Staff / Principal Level) – Backend, Infrastructure & IoT

Berlin | Full-Time | Start ASAP

We're looking for an exceptional engineer. A true A-player who wants to take ownership, build world-class technology, and play a key role in shaping the future of Heidi Systems.

About Heidi Systems

Heidi Systems is building the data infrastructure layer for buildings and energy.

We're transforming one of Europe's largest and most outdated industries by digitizing metering, consumption data, reporting, and billing. Our platform connects physical infrastructure with intelligent software, making buildings smarter, operations more efficient, and energy data accessible in real time.

We're a fast-growing, venture-backed startup with real customers, real traction, and ambitious plans to scale.

Now we're looking for a Key Engineer to become one of the technical pillars of our company.

This is not a traditional engineering position. We want someone with exceptional technical depth, strong architectural judgment, and an entrepreneurial mindset. Someone who doesn't just execute tasks but takes complete ownership of complex problems and builds solutions that last.

You'll have the autonomy to make important technical decisions, challenge existing approaches, and help define the engineering foundation of Heidi Systems.

What You'll Own

You'll take ownership of critical parts of our technology and infrastructure, working directly with the founding team.

• System Architecture: Design and evolve scalable, reliable backend and infrastructure architectures that can support rapid growth.

• Backend Engineering: Build and optimize high-performance services using Go and TypeScript.

• Data Infrastructure: Own the ingestion, validation, processing, and transformation of large volumes of meter, gateway, and building data.

• DevOps & Production: Take responsibility for our production infrastructure, CI/CD pipelines, deployments, containers, and servers.

• Database Engineering: Architect and optimize PostgreSQL environments, including performance, backups, replication, and reliability.

• IoT & Connectivity: Solve complex challenges involving MQTT, wireless gateways, device communication, APIs, and real-world hardware.

• Reliability & Monitoring: Establish robust monitoring, alerting, logging, and incident-response processes.

• Engineering Excellence: Define technical standards, improve development processes, and build the foundation for a world-class engineering organization.

• Technical Leadership: Work closely with the founders on major architectural decisions and help shape our future engineering team.

You're not here to maintain someone else's architecture. You're here to help build the architecture of a company that intends to become a market leader.

Who We're Looking For

We're looking for a top-tier engineer. Not simply someone with years of experience, but someone with an exceptional track record of building and owning complex systems.

You combine deep technical expertise with speed, pragmatism, and an uncompromising commitment to quality.

You don't need someone to tell you what to do every day. You identify problems, make decisions, take initiative, and deliver outstanding results.

What makes you an exceptional fit

• Outstanding technical expertise: You have extensive experience building, scaling, and operating complex production systems.

• Strong ownership mentality: You take full responsibility for your work, from architectural decisions to production reliability.

• Architectural excellence: You think in systems, understand trade-offs, and can design scalable solutions from the ground up.

• High execution speed: You move fast without compromising engineering quality.

• Independent problem-solving: You thrive with autonomy and don't need constant guidance or supervision.

• Hands-on mentality: You're equally comfortable designing infrastructure and debugging production issues yourself.

• Product mindset: You understand that great engineering ultimately means creating outstanding products and customer experiences.

• Leadership potential: You raise the technical bar, challenge assumptions, and can eventually mentor and lead other exceptional engineers.

• Entrepreneurial ambition: You want to build something meaningful, not just work through another backlog.

Technical Requirements

• Deep experience with backend engineering, infrastructure, DevOps, or distributed systems

• Strong proficiency in Go and/or TypeScript

• Extensive experience with PostgreSQL or comparable relational databases

• Proven ability to design, deploy, and operate production infrastructure

• Hands-on experience with Docker, CI/CD pipelines, and automated deployment workflows

• Strong understanding of APIs, data pipelines, and system performance

• Experience building monitoring, logging, and alerting solutions

• Excellent debugging and analytical skills

Bonus points for:

• MQTT, IoT, or high-volume time-series data

• Bare-metal or VPS infrastructure, particularly Hetzner

• Building and scaling engineering teams

• Experience in energy, PropTech, or infrastructure technology

• Previous experience as a founding engineer, tech lead, staff engineer, or principal engineer

Our Tech Stack

• Languages: Go, TypeScript

• Databases: PostgreSQL

• Infrastructure: Hetzner, Docker, Caddy

• CI/CD: GitHub Actions, GHCR

• Data & Connectivity: MQTT, IoT data streams, APIs

• Configuration: YAML, TOML

We care more about your ability to make excellent engineering decisions than your familiarity with every technology in our stack.

Why Join Heidi Systems?

This is an opportunity to become a key technical contributor at an ambitious company in its early growth stage.

• Real ownership: You'll own mission-critical systems and have a meaningful influence on our technology.

• Exceptional autonomy: We trust great engineers to make decisions. No micromanagement, unnecessary bureaucracy, or endless approval processes.

• Direct founder access: Work closely with the founders and contribute directly to technical and strategic decisions.

• High impact: Your work will directly shape the product, infrastructure, and future of Heidi Systems.

• Build from the ground up: Help establish the architecture, engineering culture, and technical standards for a rapidly growing company.

• Real-world complexity: Work at the intersection of software, hardware, energy infrastructure, and large-scale data.

• Long-term opportunity: Grow with the company and play an increasingly important role as we scale.

• Ambitious environment: Work with people who care deeply about quality, speed, ownership, and building something exceptional.

We're not looking for someone who simply wants another senior engineering job.

We're looking for someone who wants to become one of the engineers behind a category-defining company.

Location

Berlin, Germany – On-site

Living in Berlin or being willing to relocate is required.

Full-time position. Start as soon as possible.

How to Apply

We care much more about what you've built than how impressive your CV looks.

Send us:

• A short introduction and your CV or LinkedIn profile

• Your GitHub profile or examples of previous technical work

• One complex system you personally designed, built, or operated in production

Tell us what made that system challenging, which architectural decisions you made, what went wrong, and how you solved it.

If you're an exceptional engineer who wants real ownership, technical freedom, and the opportunity to build something significant, we'd love to hear from you.