During the years I’ve helped dozens of companies with my expertise:
Building COVID-19 passport issuing platform with Pairing.dev:
Easily one of the top 3 Freelancers I’ve ever worked with. The technical complexity Jan is able to grasp is astounding. He was on point in every call, even worked overtime when needed, and delivered a solution without bugs. We worked closely in an agile team, and I’m a Senior dev myself who checked all his code. 100% test coverage. If you have a tough nut to crack, call Jan. He’ll get it done. 5/5 would hire again!
- Build a working platform on a short 3 weeks deadline
- Bug-free release
- Helping 500 000 patients to securely obtain their certificates
- Participate in designing secure and scalable platform
Ruby on Rails Development for Scan.com:
Jan has worked with us now for a while on a number of different projects. He is a super hard working developer that gets almost anything you throw at home done quickly and at a high standard. I highly recommend him for any full stack projects, especially Ruby on Rails with React.
- Find and optimize performance bottlenecks of the application using NewRelic and ensure 99th per. of response times is below 1 second
- Extensive work on the application test suite to reduce number of bugs and achieve 99.9% user session stability according to Bugsnag
- Implement CI pipeline using Github Actions, pre-commit hooks assuring code quality using Overcommit and application downtime alerts using Pingdom
- Implement A/B tests that helped us to increase search results page conversion by 2%
Ruby on Rails / Elixir Development for Charper Bonaroo:
He is a great all-round developer that’s there when you need him. Just give him something to do and he does what’s being asked, not more, not less, without wasting resources or asking too many questions. Delivered code fits the project’s style and doesn’t stand out negatively. Jan also has no problems with improving the project by improving documentation or setting up CIs or deployment targets.
Ruby on Rails / React Development for Diagonal:
Jan did a great job. He communicated very well. During the project there were a lot of new things coming up. Jan was very professional and did an absolutely great job.
Fix broken Rails application, code quality review for BioMark:
We had a broken project and he came in and got it running in no time! Later, we asked him to do a code review of our Ruby on Rails codebase, and he did a terrific job with his many recommendations. Would hire again if we have more Ruby work.
Ruby on Rails Development for Auditi:
Top notch developer, who was a big help during a staffing shortage with out internal team! Would definitely hire again.
Ruby on Rails Development for Xomly:
Jan was great at giving recommendation on improvements to the plans and getting work done in a timely manner. He was very responsive and got everything done to our satisfaction. I would recommend Jan for Rails projects.
Algolia Search Optimization for Zentered:
Everything went great from the initial contact to discussing the project, implementing the solution and support / changes afterwards. Jan was very professional and delivered great work. Thanks!