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Python Backend Developer

Bucharest, Romania · Backend developer

CO2HERO is fast becoming the world's leading app to take climate action. 

We connect businesses committed to a positive impact for the planet with a global community committed to making eco-friendly choices. In particular, we guide our users to cut down on their CO2 emissions through different lifestyle activities such as commuting, recycling, reusing, food .... just to name a few. 

CO2HERO is a (SaaS) scale-up. Our clients are Fortune 500 companies. We have a global vision and exist to encourage change in everyday behaviour, in a balanced way.

 As one of our customers said “CO2HERO is a one-stop platform for carbon-friendly actions that combines gameplay, competition, and climate science no matter where people may be in the world”. 

With roots in Scandinavia, we continue to build momentum towards a better tomorrow - for all of us. 

Based in Copenhagen, you will report directly to, and work closely with our Chief Technology Officer to bring to life our CO2HERO Development Strategy. 

Join our team, already with 8 different nationalities where the company language is in English. We are working closely together across borders to improve our daily lives.  


  • Backend development in Python, GraphQL/REST API’s and PostgreSQL
  • Interaction with other members of the project team
  • Estimation management, code review
  • Extending our proprietary framework (We are not using Django)
  • Analyzing and troubleshoot complex problems in a timely and accurate manner
  • Actively looking for security vulnerabilities in the code, in code reviews, and in the project design


Required skills

  • 3+ experience with Python and SQL using psycopg2
  • Experience with advanced queries in SQL without using ORM
  • Experience with PostgreSQL
  • Experience with Panda & Numpy
  • Solid knowledge of object-oriented programming and experience in a low level programming language
  • Experience with implementing based on security by design
  • Experience with performance tuning and improvements
  • Experience with caching
  • Write clean and well-documented code
  • Analytical thinking
  • Experience with UnitTesting based on testing logic and not just code coverage


  • Understanding and experience with GraphQL
  • Experience with NoSQL databases
  • Experience with Git / GitHub
  • Experience with Microservice architecture and messaging

As part of our team, you’ll enjoy

  • Ability to work directly with Lead developer from Denmark who has wide experience working with global dev teams
  • Working in a team of smart, creative people
  • Flexible working hours
  • Paid vacation
  • Paid sick-leaves
  • Corporate events
  • Nice office in Bucharest
  • Coffee and cookies in the kitchen, parties, lunches, etc.