What clients, employers, colleagues and students think about Konstantin's work. 19 testimonials from 11 countries.

"Come for a solution, stay for years."

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Outstanding full-stack developer. Very easy to work with, proactive recommendations, always on time with extremely high quality results.

Feb 2024 via Upwork

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Kos has very high standards for his own performance/ethics and delivers high quality work. He helped us get a functional site up very quickly at a reasonable/honest cost...

Oct 2023 via Upwork

Dmirii Fedorov
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System Administrator at Freelance

Grateful for Konstantin's help in my career development. His ability to find simple words to explain complex concepts and optimistic attitude really make a difference.

Aug 2023 via Linkedin

Rasmus Henriksson
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Founder at Biotickr

Konstantin was a great strategic partner during our development project and delivered an excellent product exactly according to specification, using the latest in modern web development. His great communication skills meant frequently checking in, asking clarifying questions as well as providing pro's and con's of each development option. I would recommend anyone to work with Konstantin!

Jan 2023 via Linkedin

Aleksandr Grenishin
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Frontend Developer at Uploadcare

It was a pleasure to collaborate on our @uploadcare/nextjs-loader with Konstantin. He is heavily experienced in Next.js and React stacks, keeping abreast of their updates. Knows everything about responsive images. It was easy to communicate with, and I felt like we were on the same wavelength. So I can highly recommend Konstantin for any front-end project.

Nov 2022 via Linkedin

Franz Gangkofer
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Senior Software Engineer II - Techlead at Westwing

Konstantin worked in my team at Westwing and contributed a lot of expertise in frontend as well as in backend development. He is always pushing to improve the system and processes is in that sense very involved and proactive. Though he prefers frontend development and the higher direct visibility of it, he also has a very good understanding of backend development and other components of the software development area. He is a polite and positive person and is also very communicative so that you will always know what to expect. It was a pleasure working with you.

Mar 2021 via Linkedin

Christopher Roberts
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COO at Colmenero Digital

Konstantin is a highly talented Technical Lead and Software Engineer. One of the best I have worked with across many years in digital and Web development. He is especially good working with founders on MVP creation or full production versions over a series of iterations. He is creative, flexible, adapts quickly to new challenges and can cover all aspects of web development. A pleasure to work with. Highly recommended.

Jan 2020 via Linkedin

Frances Blane
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Founder at Let's Talk Dentures

Konstantin was my first experience using overseas freelancers. I must say I soon became aware of Konstantin's honesty and gentle communication. I am a novice in this field. Konstantin was constantly making sure that I understood what he was doing to the site. He was like a big brother looking after me. I am pleased to have met him. I am much more confident now in relating to freelancers of another country.

Feb 2017 via Upwork

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I am so happy with Konstantin. All my questions were answered and my Drupal 6 site is in safe hands. He knows so much. 100% satisfaction and treated with great respect. He is a true web professional who knows how to treat clients (refreshing communication).

Feb 2016 via Upwork

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Konstantin is an excellent engineer who approaches development with a rigorous technical process.

Sep 2015 via Upwork

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Konstantin did a great job on our project. His technical skills are quite good and his communication is excellent. I would definitely hire him again!

May 2015 via Upwork

Aleksandr Borkov
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Backend Engineer at Freelance

I took advanced Drupal development course provided by Konstantin in 2015. Even though I had some initial knowledge of Drupal, it still was a black box for me and I needed to learn it deeper. The course consisted of eight webinars and a home assignment after each of them. The assignments were not trivial and required a lot of hard work but Konstantin supported us by answering our questions and providing additional materials. I have to admit that after completing all the assignments I felt the power to build anything with Drupal. All in all, the course had a very positive impact to my career and I can recommend it to those who are ready to get their hands dirty to learn Drupal development from inside out.

Feb 2015 via Linkedin

Eugene Magonov
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Founder at Radiomed LLC

We found Konstantin after one big and pretty famous web development agency in St. Petersburg failed to do the job for our medical radiologists community, radiomed.ru. The company just took the money and didn’t do anything after six month of so called "development". I admit that the job was not simple (yet really hard) and consisted of several parts, including migration of huge Drupal 6 website with more than 20K nodes and more than 200K comments to the new D7 system, development of several new modules with unique functionality and many more.

When I wrote to Konstantin, he became very interested in our project, and we spent some time discussing the details of the new website. I have to mention that it was a great pleasure to work with Konstantin starting from the very first email and till the day when the work was done. Based on our vision of the new website, he wrote comprehensive plan of site migration, new modules and theme development so we all knew what to expect. My stupid questions were patiently answered, too.

After the plan was developed, Konstantin began to work hard and surprisingly fast, especially when compared to the web agency mentioned above. There were several serious problems on the way that were mostly caused by the wrongly configured old D6 site and some server configuration issues. Thanks to Konstantin, all these problems were solved successfully and he also explained us every bit of information about what he was doing. Konstantin showed himself as a great Drupal, PHP and MySQL specialist. He is also the best HTML theme developer with the great knowledge of HTML, CSS and Javascript. Not to mention GIT and general Linux server knowledge that he certainly has on a highest level.

All these things wouldn’t mean anything without Konstantin’s passionate willingness to make the best of what’s possible in every single task. And it’s all combined with his honesty and tendency to make more than was planned for the less money. Yet, there was a bunch of great improvements in our project that were made by Konstantin on his own, and he didn’t charge us any extra for these goodies!

Last, but not least. Konstantin is a great person to talk not only on IT topic. I remember the cute story he told about injured in a car accident dog that he and his wife saved from a certain death. This story is a good illustration to Konstantin’s kind soul, which is when combined with outstanding technological skills makes him the best freelance web developer I ever knew.

Thank you for your great job, Konstantin!

Feb 2015 via Linkedin

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Konstantin did perfect work. He really knows Drupal and unless many others who claim to be Drupal programmer on oDesk, he really knows Drupal and really knows how to code in Drupal. I can recommend him for any Drupal task, especially when you have some more sophisticated tasks.

Feb 2015 via Upwork

Aaron Homer Vergara
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Web Developer at Explorable AS

I had fun working with Konstantin. I learned a lot from him at the same time. He's the kind of developer that makes sure the project is stable and future proof. And he gives great attention to scalability and performance.

Nov 2014 via Linkedin

Oskar Blakstad
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CEO at Explorable AS

Konstantin was simply AMAZING to work with! No need to look further - this is the guy to hire. He is highly skilled, really devoted, great on communication, very clear about when it can be completed. He also works great independently and is very responsible and great at finding the optimal solutions if you ask him to solve a problem. I simply loved working with Konstantin.

Nov 2014 via Upwork

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Highly competent, committed and methodical Drupal developer with an excellent work ethic. One of the best developers we ever worked with on Upwork.

Jan 2014 via Upwork

Vladimir Volkov
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Senior Software Developer at DataArt

Konstantin has excellent Drupal expertise with many contributed modules, implementation of his own modules and configuration of high-load projects. He is always attentive to project details and client needs. I would strongly recommend him for Drupal projects.

Jan 2013 via Linkedin

Alexander Sorokin
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Lead Web Developer at Team Force LLC

Konstantin worked on our Drupal team for almost 3 years. He demonstrated great development skills and creativity in problem troubleshooting. He is a very executive and hard-working person. Konstantin gets things done right and with deadlines. I was glad to work with him.

Nov 2012 via Linkedin