Aleksander Janiszewski
Staff Software Engineer at Airbnb
Berlin Metropolitan Area Germany
Summary
🤩
RockstarAleksander Janiszewski is a Staff Software Engineer based in Berlin with 15 years of experience building maintainable web platforms and leading engineering teams at Airbnb and HotelTonight. He brings deep expertise in Ruby, design patterns, BDD, Git and Vim, and a strong track record of improving code quality both in production systems and in prominent open-source projects like RSpec and geocoder. A polyglot thinker increasingly focused on machine learning, he combines hands-on implementation with pragmatic architecture and developer ergonomics. Aleksander is also an experienced manager, coach, and public speaker who enjoys mentoring engineers and fostering continuous learning. His open-source contributions reveal a particular attention to long-term maintainability—refactoring core testing primitives and silencing subtle warnings that can erode developer confidence.
15 years of coding experience
15 years of employment as a software developer
English, Polish, German, French
Github Skills (6)
testing10
rspec10
google-geocoding-api10
refactoring10
geocoding10
ruby10
Programming languages (6)
Github contributions (5)
rspec/rspec-core
Jan 2012 - Jan 2013
RSpec runner and formatters
Role in this project:
Backend Developer
Backend DeveloperContributions:7 commits in 11 months
Contributions summary:Aleksander primarily focused on improving the RSpec core library. Their contributions involved fixing warnings related to deprecation and variable shadowing, indicating a focus on code quality and maintenance. They also refactored and improved the implementation of `let` and `subject` methods, including updates to the `its` method, enhancing testing functionality.
railsrubyrspecrspec-runnerformatters
alexreisner/geocoder
Feb 2014 - Feb 2014
Complete Ruby geocoding solution.
Role in this project:Back-end Developer
Back-end DeveloperContributions:6 commits in 1 day
Contributions summary:Aleksander primarily focused on improving the codebase's quality and maintainability. Their contributions involved fixing warnings related to ambiguous arguments, unused variables, and uninitialized variables. They also addressed circular require warnings and fixed private attr_reader warnings. The user made changes across multiple files to resolve these issues, suggesting a broad understanding of the project's structure.
geocoding-objectsmongoidgeocodingrubygeocoding-requests
Find and Hire Top DevelopersWe’ve analyzed the programming source code of over 60 million software developers on GitHub and scored them by 50,000 skills. Sign-up on Prog,AI to search for software developers.