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Kostiantyn A.
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Kostiantyn A.

Full-Stack JavaScript Developer | React/Next/Node/Express

Hi everyone 👋 I'm a high-skilled (7+ years) Full-Stack Developer. I have 8,000+ hours of a proven track record and 16 completed jobs here on Upwork. Through many projects, I have mastered problem-solving skills and just fell in love with what I'm doing. Creating new products is what brings me much more joy than anything else. I especially like small and big projects that require uncommon approaches and use of the most efficient methods. My skills: — JavaScript/ES6; — Typescript; — Cursor, Claude Code; — Node.js, Express.js; — React.js/Next.js; — Redux/Redux Toolkit/Tanstack-Query/Zustand/React Context; — HTML5, CSS3 and LESS (SASS); — React-Native IOS/Android, Expo; — Material UI, Ant Design, styled-components, Tailwind; — Agile: Jira, Trello, Notion, Linear and Slack; Other: Webpack, REST APIs, Git, Docker, GitHub Actions (CI/CD pipeline). Databases: MongoDB, Mongoose, Firebase/Firestore, Planescale, Supabase, ClickHouse Familiar with: AWS, Electron, Inngest, Redis. I'm open to both part-time and full-time positions, so feel free to send me an invitation any time! You'll be rewarded once we work together :)

🇺🇦Zaporizhzhia, Ukraine$30/hr100% JSS4.21 (13)Since Aug 2019

Earnings and projects

MRR
$2.5k

Last 6 months ÷ 6

World#16,750 / 412k
🇺🇦Country#986 / 14.3k
Revenue, last 30 days
$0

Last 6 months: $15k

Total earnings
$252k

Billed in all: $259k

World#10,566 / 412k
🇺🇦Country#870 / 14.3k
Per project
$16k

$15k in the last 6 months

World#8,634 / 412k
🇺🇦Country#674 / 14.3k
Projects, last 6 months
1
0% fixed100% hourly
World#128,092 / 412k
🇺🇦Country#4,718 / 14.3k
Projects in all
16

Across 19 contracts

5% fixed95% hourly
World#155,087 / 412k
🇺🇦Country#6,448 / 14.3k

Earnings, last 30 days

$259kNothing earned in the last 30 daysBilled in all, before Upwork's fee · drag across the chart to see what was earned in any stretch
$250k$255k$260k$265kOct 8Oct 23Nov 7

Skill rankings: Top 4% in ExpressJS

Ranked by MRR among everyone on Upwork with the skill.

  1. #9Mobx103 freelancers · 🇺🇦 #5Top 9%
  2. #14styled-components191 freelancers · 🇺🇦 #8Top 7%
  3. #58Material UI1,027 freelancers · 🇺🇦 #18Top 6%
  4. #165Redux3,245 freelancers · 🇺🇦 #58Top 5%
  5. #237ExpressJS5,651 freelancers · 🇺🇦 #24Top 4%
  6. #359RESTful API6,064 freelancers · 🇺🇦 #39Top 6%
  7. #617MongoDB10,865 freelancers · 🇺🇦 #75Top 6%
  8. #1,757Node.js25,795 freelancers · 🇺🇦 #199Top 7%