Hi! My name is Mostafa. I am a senior iOS Software Engineer, I have been building iOS apps for clients since 2017 and I work as a contractor with teams from all over the world. I am the founder and lead engineer of Keystone Systems, and I do every audit personally.

Most of my work starts with an app audit. Companies bring me in to find out why their app is slow, unstable, or expensive to change, and they leave with a clear plan. When they want the plan executed, Keystone takes that on too, as a fixed-price rescue and modernization project. I spent three years as a senior iOS engineer on a weather app used by millions of people, working on its performance and reliability.

I help teams ship features steadily, modernize legacy code, and improve performance & stability without slowing down delivery. I integrate quickly into existing workflows (tickets, PR reviews, releases) and focus on work that reduces risk and saves future engineering time. Based in the Netherlands (CET), available for remote work

Working with me gets you:

• Weekly progress updates with clear scope and risk flags

• Pragmatic refactors that improve velocity

• Performance: slow screens, leaks, startup time, scrolling hangs

• Stability: crash investigation, monitoring and prevention

• Testing strategy aligned to risk areas + CI-friendly PRs

• Documentation and handoff so your team can keep moving

If you’re looking for senior iOS support, either contracting or a focused sprint, book a quick intro call and I’ll suggest the fastest path forward.