Sergey Kuznetsov
Lead Engineer at Klarna
Stockholm, Sweden
Summary
👤
Senior🎓
Top SchoolSergey Kuznetsov is a Lead Engineer based in Stockholm with 16 years of experience building resilient backend systems and coaching high-performing teams across remote and distributed environments. He combines deep expertise in Elixir, Ruby, and JavaScript with a pragmatic focus on system design, maintainability, and engineering best practices. Sergey has led and scaled teams at Klarna and Budbee, guided global clients as a Principal Alchemist, and delivered measurable product impact—such as an in-house eSignature that saved $50K/year and increased adoption significantly. An active open-source contributor, he has improved error reporting and test coverage in well-known projects like Errbit, reflecting a penchant for iterative refinement and long-term maintenance. Known for bridging hands-on engineering with leadership, he often drives process improvements, documentation initiatives, and mentoring programs that accelerate team throughput. Beyond code, Sergey’s curiosity for distributed systems and functional programming fuels pragmatic architectural choices that balance reliability with developer velocity.
16 years of coding experience
19 years of employment as a software developer
Master's degree Information Technology and Computers Applied Computer Science, Master's degree Information Technology and Computers Applied Computer Science at Saratov State Technical University
English, Russian
Stackoverflow
8,721reputation
1.8mreached
82answers
0questions
jquery
top-5%
php
top-1%
javascript
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dynamic
top-5%
Github Skills (20)
testing10
ruby10
php10
error-log10
javascript9
ruby-rails9
jquery9
rails9
dynamic9
gitlab8
airbrake7
crash-reports7
html6
asset-pipeline6
ruby-on-rails6
Programming languages (9)
Github contributions (5)
errbit/errbit
Sep 2012 - Nov 2012
The open source error catcher that's Airbrake API compliant
Role in this project:
Back-end Developer & QA Engineer
Back-end Developer & QA EngineerContributions:6 commits in 2 months
Contributions summary:Sergey primarily focused on enhancing the error-reporting functionality and improving test coverage for the Errbit application. They fixed a bug related to URL generation for GitHub file references. The user also added tests to validate the updated functionality and refactored code to incorporate Gitlab tracker integrations. Furthermore, they reverted an old method and corresponding spec fixes, suggesting ongoing maintenance and iterative refinement of the codebase.
apicatchererror-monitoringcompliantairbrake
cr0t/ruby-on-whales
Nov 2019 - Apr 2021
Contributions:14 commits, 1 push in 1 year 4 months
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