Ruby Backend Developer – SRE Team Published: August 27, 2020
Krakow, Poland
Job Type


At Castle, we're on a mission to protect online users against hackers and bots. Our vision is to be the easiest and most developer friendly way of adding user account security processes to your platform. Using our APIs, companies can track user interactions to figure out when accounts have been compromised, as well as giving their users the ability to recover their accounts eg. by sending out an email notification or text message.
We are looking for a Ruby Backend Developer to join our SRE team, working on our central platform that allows the analysis of data coming from a myriad of events. Working together with a small but influential team, you will have a significant impact on the product shape. This role is a great opportunity for people seeking creativity and impactfulness of their work.


    • Design, build and maintain efficient, reusable, and reliable Ruby and Ruby on Rails code
    • Design and develop backend solutions and APIs
    • Have some basic knowledge of frontend solutions
    • Write unit and functional automation tests
    • Maintain and troubleshoot existing applications codebase
    • Ensure security and SLAs compliance of our APIs
    • Integrate data storage solutions
    • Design and develop applications in an agile development environment
    • Build features with a major focus on performance, scalability and future expansion
    • Identify opportunities for improvement in system interfaces
    • Work productively with product team members to ensure feature requirements are adequately scoped and clearly defined
    • Onboard and mentor new team members
    • Includes some after-hours on-call responsibilities


    • 5 years of experience with Ruby and the Rails framework
    • 5 years of experience with SQL backends, preferably PostgreSQL
    • Experience with Git and Github
    • Experience with CI/CD tools like CircleCI/TravisCI/GitHub Actions
    • Experience working in a collaborative agile development environment
    • Experience in Unit Testing or Test-Driven Development
    • Experience or ability to mentor other developers

Knowledge, Skills, and Abilities

    • Knowledge of Docker and Docker-based deployment
    • Knowledge of distributed system design patterns
    • Good understanding and experience developing and consuming RESTful services
    • Deep understanding of good software engineering practices (version control, code reviews, testing, refactoring)
    • Good time-management skills
    • Fluency in English (both spoken and written)
    • Excellent organisational skills
    • Attention to detail: must be able to manage a complex project and maintain accuracy while working on complex tasks
    • Strong problem solving and debugging skills, eye for detail, ability to anticipate and find corner cases
    • Ability to design data models
    • Ability to work collaboratively and to communicate effectively both with other developers and with non-technical colleagues

Perks and Benefits

    • Competitive salary package
    • We provide a full hardware package: MacBook Pro, noise-cancelling headphones, 27-inch screen
    • Remote work budget for equipment needed to work remotely
    • Development opportunities, including IT conferences, internal training, an individual development budget
    • Employee stock purchase plan
    • Flexible work hours
    • Annual offsites, team events and the possibility to visit and work from our offices in Cracow, Malmö and San Francisco
Castle has a positive, inclusive, and supportive culture and the folks we seek are passionate about evolving it. Creating a place of belonging for all individuals is part of our core ethos, and we are committed to fostering a safe and productive environment where everyone can do their best work. Together, we aim to be humble, hardworking, solution-oriented and, above all, good team players who get things done. If this sounds like you, we encourage you to apply even if your experience doesn't precisely match the job description.
Note: This role is fully remote within the EU

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