Senior Backend Developer (Ruby on Rails)

Ruby

Targowa 35, Łódź

Ragnarson

140 - 160PLN

Net per hour - B2B

Full-time

B2B

Senior

Remote

Tech stack

English

C1

Ruby on Rails

master

PostreSQL

advanced

Solid

advanced

JSON

advanced

ClickHouse

advanced

IoT devices

regular

GraphQL

regular

Job description

🚀 Wondering what would make you a better developer at this stage of your career? By working with dozens of different developers, we concluded that in many cases, it’s not only about your technical skills. It might be about your soft skills and looking at problems with the big picture in mind. Many companies and environments support the development of technical skills. There are only a handful, including Ragnarson, that focus on shaping developers as well-rounded professionals.

🧩 About the Project

We are looking for an experienced Senior Backend Developer (RoR) to join one of our clients – a fast-growing technology company operating in the environmental and property data management space.

The project focuses on building a large-scale data platform that monitors and analyzes utility consumption (electricity, heating, water) across extensive real estate portfolios. The platform integrates with hundreds of thousands of devices and external data sources to provide users with accurate, real-time insights that support sustainability goals, compliance, and operational efficiency.

Handling millions of time-series records daily, the system is designed for scale, performance, and robustness – and your role will directly contribute to shaping its architecture and future direction.

📍 Remote (within the EU)

🕓 Full-time | B2B or Employment Contract

🐦💻 What you'll do

• Design and implement backend features and scalable APIs

• Work with large datasets and time-series data from metering devices

• Collaborate with cross-functional teams to deliver high-quality features

• Identify performance bottlenecks and optimize queries and services

• Help shape architectural decisions and improve engineering best practices

🎯 What do we expect

• 5+ years of experience working with Ruby on Rails in production

• Strong knowledge of Ruby language and Rails internals

• SOLID :) understanding of software design principles (e.g. SOLID, modular design, decoupling strategies)

• Experience designing and scaling RESTful APIs for high-traffic applications

• Familiarity with JSON:API, versioning strategies, and API architecture

• Strong PostgreSQL skills, including query tuning and indexing

• Experience working with analytical databases (preferably ClickHouse or similar columnar stores like Redshift, Vertica)

• Background job processing experience (Sidekiq or similar)

🎯 Nice-to-have:

• Production experience with ClickHouse

• Familiarity with multi-tenant SaaS architectures

• Exposure to the energy/utility domain and relevant data formats/protocols

• Experience integrating with IoT devices and normalizing incoming data

• Understanding of Domain-Driven Design (DDD)

• Background in building systems for real estate or energy management

• Bonus: familiarity with GraphQL and/or Elixir

What do you get by joining us?

Ragnarson was founded in 2006 as a web development agency. In 2019, we started investing in early-stage impact-driven startups. We act as a software agency and angel investor, investing and co-creating products with founders.

Our focus on projects that combat climate change and socio-economic inequalities is what sets us apart from the crowd. We count on and rely on mature individuals with broad interests. They gain access to all crucial information within the company, and based on this, they make critical decisions.

If you are an aspiring technical lead, you will have an excellent opportunity to be exposed to various situations, which will help you develop relevant skills. Nothing happens if you don’t get out of your comfort zone. Ragnarson offers a great place to give you the right push.

We also offer:

• 100% remote work

• Open company financial records (for example, income, expenses, forecast)

• Transparent communication and company documents

• Opportunity to develop in non-programming fields (project management, customer relations, recruitment, marketing, sales)

• Various benefits (MacBook Pro, co-funding of the healthcare package, sports activities, etc.)

Published: 07.08.2025

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