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Aleksandr K.
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Aleksandr K.

Senior Web & Mobile Developer | Scalable & High-Load Systems

For 15+ years, I’ve built web and mobile apps that run reliably in production — not just demos. Clients come to me when systems need to stay stable under load and behave predictably. I focus on architecture and delivery that actually work in real conditions. I’ve delivered 100+ projects, including high-load systems with millions of users. My experience covers VPN & cybersecurity solutions, banking software, AI tools, real-time tracking systems, and scalable mobile/web platforms with complex functionality — along with other non-trivial systems. Tech: • Swift (UIKit / SwiftUI), Kotlin (Jetpack, Coroutines) • React (Next.js), Vue • Node.js (NestJS / Express), PHP (Laravel / Yii2) • WebSockets, TCP/UDP • REST / GraphQL APIs • Stripe / PayPal • Firebase, Amplitude, AppsFlyer, RevenueCat • OpenAI, Gemini, Claude, vector DBs • JWT, OAuth2, encryption, secure storage I handle architecture and key decisions myself. If needed, I involve additional developers — always transparently. Process is straightforward: define scope → plan → build → test → release → support. No overengineering, no surprises. If you need help with a new project or improving an existing one — send a short description, and I’ll quickly outline the best way to approach it.

🇺🇦Zhytomyr, Ukraine$35/hr100% JSS4.98 (14)Since Jan 2012
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Earnings and projects

MRR
$173

Last 6 months ÷ 6

World#118,324 / 412k
🇺🇦Country#4,366 / 14.3k
Revenue, last 30 days
$0

Last 6 months: $1k

Total earnings
$237k

Billed in all: $237k

World#11,701 / 412k
🇺🇦Country#957 / 14.3k
Per project
$8.2k

$346 in the last 6 months

World#20,401 / 412k
🇺🇦Country#1,402 / 14.3k
Projects, last 6 months
3
100% fixed0% hourly
World#66,479 / 412k
🇺🇦Country#2,681 / 14.3k
Projects in all
29

Across 32 contracts

81% fixed19% hourly
World#100,215 / 412k
🇺🇦Country#4,394 / 14.3k

Earnings, last 30 days

$237kNothing earned in the last 30 daysBilled in all, before Upwork's fee · drag across the chart to see what was earned in any stretch
$232.5k$235.0k$237.5k$240.0kOct 8Oct 23Nov 7

Skill rankings: Top 11% in RxJava

Ranked by MRR among everyone on Upwork with the skill.

  1. #8RxJava73 freelancers · 🇺🇦 #2Top 11%
  2. #21Android NDK94 freelancers · 🇺🇦 #4Top 22%
  3. #163Android SDK805 freelancers · 🇺🇦 #19Top 20%
  4. #719Kotlin3,021 freelancers · 🇺🇦 #54Top 24%
  5. #815Swift3,634 freelancers · 🇺🇦 #76Top 22%
  6. #991iOS3,908 freelancers · 🇺🇦 #99Top 25%
  7. #1,142Android4,975 freelancers · 🇺🇦 #119Top 23%
  8. #1,599Java8,313 freelancers · 🇺🇦 #106Top 19%