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Mark J.

Mark J.

Mobile App Developer | iOS, Android, React Native

With 25 years in software development and 50+ products delivered, I help startups, growing businesses, and Fortune 500 organizations turn ideas into reliable, production-ready mobile applications. 𝑵𝒐𝒕 𝒔𝒖𝒓𝒆 𝒘𝒉𝒂𝒕 𝒕𝒉𝒆 𝒓𝒊𝒈𝒉𝒕 𝒑𝒂𝒕𝒉 𝒊𝒔 𝒇𝒐𝒓 𝒚𝒐𝒖𝒓 𝒂𝒑𝒑? 𝑶𝒏𝒆 𝒄𝒐𝒏𝒗𝒆𝒓𝒔𝒂𝒕𝒊𝒐𝒏 𝒘𝒊𝒕𝒉 𝒎𝒆 𝒄𝒂𝒏 𝒕𝒖𝒓𝒏 𝒕𝒉𝒆 𝒎𝒐𝒗𝒊𝒏𝒈 𝒑𝒊𝒆𝒄𝒆𝒔 𝒊𝒏𝒕𝒐 𝒂 𝒄𝒍𝒆𝒂𝒓, 𝒑𝒓𝒂𝒄𝒕𝒊𝒄𝒂𝒍 𝒑𝒍𝒂𝒏, 𝒔𝒐 𝒚𝒐𝒖 𝒌𝒏𝒐𝒘 𝒘𝒉𝒂𝒕 𝒏𝒆𝒆𝒅𝒔 𝒕𝒐 𝒃𝒆 𝒃𝒖𝒊𝒍𝒕, 𝒉𝒐𝒘 𝒕𝒐 𝒂𝒑𝒑𝒓𝒐𝒂𝒄𝒉 𝒊𝒕, 𝒂𝒏𝒅 𝒘𝒉𝒂𝒕 𝒕𝒐 𝒅𝒐 𝒏𝒆𝒙𝒕. I build iOS, Android, and React Native applications with a broader view of what it takes to make a product succeed, like connecting the mobile experience with the APIs, backend systems, cloud infrastructure, payments, authentication, and third-party services behind it. This broader engineering perspective helps me identify technical challenges early and deliver mobile products that are reliable today and built to evolve tomorrow. ⭐𝐖𝐡𝐚𝐭 𝐈 𝐒𝐩𝐞𝐜𝐢𝐚𝐥𝐢𝐳𝐞 𝐈𝐧: 𝐢𝐎𝐒 & 𝐀𝐧𝐝𝐫𝐨𝐢𝐝 𝐀𝐩𝐩𝐬 Native mobile applications using Swift, SwiftUI, and Kotlin, as well as cross-platform applications using React Native. 𝐀𝐈-𝐏𝐨𝐰𝐞𝐫𝐞𝐝 𝐌𝐨𝐛𝐢𝐥𝐞 𝐀𝐩𝐩𝐬 AI features and integrations using OpenAI and ChatGPT, including AI assistants, chatbots, agents, recommendations, intelligent workflows, and AI-powered product features. 𝐌𝐕𝐏𝐬 & 𝐍𝐞𝐰 𝐏𝐫𝐨𝐝𝐮𝐜𝐭𝐬 From Figma designs and product requirements to a production-ready application, I can help turn your idea into a focused MVP without unnecessary complexity. 𝐄𝐱𝐢𝐬𝐭𝐢𝐧𝐠 𝐀𝐩𝐩 𝐃𝐞𝐯𝐞𝐥𝐨𝐩𝐦𝐞𝐧𝐭 Already have an application or codebase? I can help with new features, bug fixing, performance optimization, refactoring, API integrations, codebase improvements, and ongoing development. 𝐁𝐚𝐜𝐤𝐞𝐧𝐝 & 𝐀𝐏𝐈 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐢𝐨𝐧 I work with the systems your mobile application depends on, including REST APIs, Firebase, Node.js, Python, authentication, payments, subscriptions, databases, maps, geolocation, push notifications, and real-time functionality. 𝐀𝐩𝐩 𝐒𝐭𝐨𝐫𝐞 & 𝐆𝐨𝐨𝐠𝐥𝐞 𝐏𝐥𝐚𝐲 𝐋𝐚𝐮𝐧𝐜𝐡 I can take your application through production builds, testing, deployment, and Apple App Store / Google Play submission. 𝐂𝐨𝐫𝐞 𝐓𝐞𝐜𝐡𝐧𝐨𝐥𝐨𝐠𝐢𝐞𝐬: 𝐌𝐨𝐛𝐢𝐥𝐞: Swift • SwiftUI • Kotlin • React Native 𝐁𝐚𝐜𝐤𝐞𝐧𝐝: Node.js • Python • Firebase • PostgreSQL • MongoDB 𝐂𝐥𝐨𝐮𝐝: AWS • Firebase 𝐀𝐈: OpenAI API • ChatGPT • AI Assistants • AI Agents 𝐀𝐏𝐈𝐬 & 𝐈𝐧𝐭𝐞𝐠𝐫𝐚𝐭𝐢𝐨𝐧𝐬: REST APIs • Payments • Subscriptions 𝐖𝐡𝐚𝐭 𝐘𝐨𝐮 𝐂𝐚𝐧 𝐄𝐱𝐩𝐞𝐜𝐭 ⚡Clear technical planning before development ⚡Clean and maintainable code ⚡Regular working builds and progress updates ⚡Thorough testing & quality assurance. ⚡Reliable API and third-party integrations ⚡Responsive communication ⚡App Store and Google Play deployment ⚡Ongoing maintenance and feature development 𝑺𝒆𝒏𝒅 𝒎𝒆 𝒚𝒐𝒖𝒓 𝒑𝒓𝒐𝒋𝒆𝒄𝒕 𝒃𝒓𝒊𝒆𝒇, 𝑭𝒊𝒈𝒎𝒂 𝒅𝒆𝒔𝒊𝒈𝒏𝒔, 𝒆𝒙𝒊𝒔𝒕𝒊𝒏𝒈 𝒂𝒑𝒑, 𝒄𝒐𝒅𝒆𝒃𝒂𝒔𝒆, 𝒐𝒓 𝒊𝒅𝒆𝒂. 𝑰'𝒍𝒍 𝒓𝒆𝒗𝒊𝒆𝒘 𝒊𝒕 𝒂𝒏𝒅 𝒉𝒆𝒍𝒑 𝒚𝒐𝒖 𝒅𝒆𝒕𝒆𝒓𝒎𝒊𝒏𝒆 𝒕𝒉𝒆 𝒎𝒐𝒔𝒕 𝒑𝒓𝒂𝒄𝒕𝒊𝒄𝒂𝒍 𝒑𝒂𝒕𝒉 𝒇𝒐𝒓𝒘𝒂𝒓𝒅.

🇺🇸Boston, United States$35/hr100% JSS5.00 (3)Since Oct 2012

Earnings and projects

MRR
$12

Last 6 months ÷ 6

World#170,571 / 412k
🇺🇸Country#22,398 / 62.1k
Revenue, last 30 days
$0

Last 6 months: $74

Total earnings
$3.2k
World#293,531 / 412k
🇺🇸Country#45,659 / 62.1k
Per project
$1.1k

$74 in the last 6 months

World#119,623 / 412k
🇺🇸Country#20,398 / 62.1k
Projects, last 6 months
1
100% fixed0% hourly
World#128,092 / 412k
🇺🇸Country#16,472 / 62.1k
Projects in all
3
100% fixed0% hourly
World#304,140 / 412k
🇺🇸Country#44,018 / 62.1k

Earnings, last 30 days

$3.2kNothing earned in the last 30 daysBilled in all, before Upwork's fee · drag across the chart to see what was earned in any stretch
$3,100$3,150$3,200$3,250Oct 8Oct 23Nov 7

Skill rankings: Top 31% in Swift

Ranked by MRR among everyone on Upwork with the skill.

  1. #39App Feature Development66 freelancers · 🇺🇸 #5Top 59%
  2. #86Android UI Design239 freelancers · 🇺🇸 #3Top 36%
  3. #197Mobile QA378 freelancers · 🇺🇸 #13Top 52%
  4. #318Native App Development833 freelancers · 🇺🇸 #24Top 38%
  5. #786AI Mobile App Development1,401 freelancers · 🇺🇸 #39Top 56%
  6. #835Mobile App Testing1,834 freelancers · 🇺🇸 #62Top 46%
  7. #1,019Kotlin3,021 freelancers · 🇺🇸 #56Top 34%
  8. #1,105App Development2,592 freelancers · 🇺🇸 #133Top 43%