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.
Earnings and projects
Last 6 months ÷ 6
Last 6 months: $74
$74 in the last 6 months
Earnings, last 30 days
Skill rankings: Top 31% in Swift
Ranked by MRR among everyone on Upwork with the skill.
- #39App Feature Development66 freelancers · 🇺🇸 #5Top 59%🇺🇸#5 of 6
- #86Android UI Design239 freelancers · 🇺🇸 #3Top 36%🇺🇸#3 of 9
- #197Mobile QA378 freelancers · 🇺🇸 #13Top 52%🇺🇸#13 of 23
- #318Native App Development833 freelancers · 🇺🇸 #24Top 38%🇺🇸#24 of 42
- #786AI Mobile App Development1,401 freelancers · 🇺🇸 #39Top 56%🇺🇸#39 of 73
- #835Mobile App Testing1,834 freelancers · 🇺🇸 #62Top 46%🇺🇸#62 of 139
- #1,019Kotlin3,021 freelancers · 🇺🇸 #56Top 34%🇺🇸#56 of 158
- #1,105App Development2,592 freelancers · 🇺🇸 #133Top 43%🇺🇸#133 of 297