Senior Backend Engineer

Helicon Technologies AB; Stockholms kommun; On-site; SEK 700,000 - 900,000; Full time

Job summary

Helicon Technologies AB in Sweden is seeking a Senior Backend Engineer to help build the energy software systems that connect assets, time-series data, and energy markets. You’ll design and implement backend services, APIs, and data platforms that scale across thousands of devices and millions of measurements.

You’ll work with cloud platforms (AWS/Azure/GCP), modern containers, and distributed architectures, while keeping reliability and maintainability at the forefront.

Qualifications

• 5+ years of professional software development experience.
• Strong backend development skills, preferably with Python.
• Experience designing APIs, integrations, and backend services.
• Experience with relational databases and data modelling.
• Experience with AWS, Azure, or GCP.
• Good understanding of Docker, Git, and CI/CD.
• Experience designing and operating production systems.
• The ability to reason about architecture, performance, reliability and maintainability.
• The ability to communicate technical decisions clearly.
• Professional proficiency in Swedish and English.

Responsibilities

• Designing and building backend services, APIs and integrations.
• Building systems for ingesting and processing large amounts of energy and time-series data.
• Connecting cloud software with devices, industrial systems and third-party platforms.
• Designing data models and distributed architectures.
• Building services for forecasting, optimization and control.
• Taking a problem from a conversation with a customer all the way to running software in production.
• Making architectural decisions without turning every decision into an architecture project.
• Reviewing code and helping other engineers become better.
• Taking technical leadership of a project or small engineering team when needed.

Skills

5+ years of experience

Python

APIs & backend

Relational databases

Cloud platforms

Docker & CI/CD

Production systems

Architecture & design

Swedish & English

Tools

Kafka

Kubernetes

TimescaleDB

PostgreSQL

Databricks

Spark

Airflow

Job description

We build software for the energy system.

Helicon is a software engineering company specialized in energy. We work with energy companies, technology companies, and industrial customers to build the systems that connect, understand, and control the physical world.

That means everything from APIs and integrations to data platforms, optimization systems, and applications handling thousands of connected assets and millions of measurements.

Now we're looking for a Senior Backend Engineer who wants to build those systems with us.

The challenge

The energy system is becoming increasingly software-defined.

Batteries, buildings, heat pumps, EV chargers, solar panels, meters, and entire energy plants are being connected and need to exchange data, make decisions, and interact with increasingly complex energy markets.

That creates some genuinely interesting engineering problems.

How do you reliably ingest data from thousands of assets and systems that were never designed to talk to each other?

How do you build APIs and services that remain understandable as the system grows?

How do you process large amounts of time-series data and turn it into something useful in real time?

And how do you build software that customers can trust when it starts controlling physical equipment?

These are the kinds of problems you'll work on at Helicon.

We've previously built systems connecting more than 15,000 buildings and 30,000 sensors, software for optimizing energy assets, and digital twins for complex energy systems.

There's plenty left to build.

What you'll do

You'll spend most of your time building software.

Depending on the project, that might mean:

• Designing and building backend services, APIs and integrations.
• Building systems for ingesting and processing large amounts of energy and time-series data.
• Connecting cloud software with devices, industrial systems and third-party platforms.
• Designing data models and distributed architectures.
• Building services for forecasting, optimization and control.
• Taking a problem from a conversation with a customer all the way to running software in production.
• Making architectural decisions without turning every decision into an architecture project.
• Reviewing code and helping other engineers become better.
• Taking technical leadership of a project or small engineering team when needed.

We expect senior engineers to take ownership beyond their own tickets.

If something doesn't make sense, question it. If there's a simpler solution, suggest it. If something should be fixed, fix it.

You might like working here if

You genuinely enjoy software engineering.

You're comfortable moving between understanding the customer's problem, sketching an architecture, digging through an unfamiliar API, and writing the code that ultimately solves it.

You care about good engineering, but don't confuse complexity with quality.

You know that sometimes the right solution is a carefully designed distributed system, and sometimes it's a straightforward service with a database.

You like autonomy, short decision paths, and seeing what you build being used in the real world.

And you probably get slightly annoyed when a meeting could have been a Slack message.

What we're looking for

We care more about engineering ability than matching an exact technology checklist.

But you'll probably have:

• 5+ years of professional software development experience
• Strong backend development skills, preferably with Python
• Experience designing APIs, integrations, and backend services
• Experience with relational databases and data modelling
• Experience with AWS, Azure, or GCP
• Good understanding of Docker, Git, and CI/CD
• Experience designing and operating production systems
• The ability to reason about architecture, performance, reliability and maintainability
• The ability to communicate technical decisions clearly
• Professional proficiency in Swedish and English

Experience as a Tech Lead, Lead Developer, or senior engineer with significant technical ownership is valuable, but having held a particular title isn't important.

Even better if you've worked with

• Energy, IoT, or connected products
• Event-driven or distributed systems
• Large-scale time-series data
• Kafka
• Kubernetes
• TimescaleDB, PostgreSQL, or similar technologies
• Databricks, Spark or Airflow
• Optimization, forecasting, or machine learning
• Industrial systems, edge computing, or OT/IT integrations

You definitely don't need to know all of these.

How we think about engineering

Ship useful things.

Software creates value when someone uses it.

Keep it simple.

Complexity has to earn its place.

Own the problem.

Don't just implement requirements. Understand what we're actually trying to achieve.

Use the best tool for the job.

We're not interested in technology for technology's sake.

AI is part of modern software engineering.

We expect our engineers to use modern AI tools where they make them faster and better, while still understanding the systems and code they build.

Leave things better than you found them.

Good engineering compounds. We want every project to improve the way we build the next one.

Why Helicon?

Because there aren't many places where a backend engineer gets to work with problems spanning cloud software, large-scale data, physical infrastructure, and the energy system.

We're small enough that good engineers have a real influence on how things are built.

You'll work alongside experienced engineers and data scientists, have significant technical autonomy, and get close to both the customer and the actual problem.

And you'll get to build software where changing a few lines of code can ultimately change how a building, battery, or energy system behaves in the physical world.

That's pretty cool.