Senior Mobile Engineer & Consultant
I help product teams build mobile apps that are fast, scalable, and ready to grow.
A senior Flutter & Android engineer companies bring in when their mobile product is business-critical — for architecture, performance optimisation, SDK development, and rescuing large apps that have gotten slow or hard to maintain. Over a decade shipping to millions of users, where an engineering decision shows up directly in retention and revenue.
Native Android to Flutter, at production scale.
Apps I have architected, migrated, and kept stable.
Consumer apps optimised for speed and reliability.
Through a live migration on a 1M+ user app.
Why clients hire me
Companies bring me in to fix hard mobile problems.
Not to add another pair of hands — to make a specific, measurable difference to how their app performs, scales, and holds up as it grows.
Improve app performance
Cold start, jank, memory, and crashes — measured and fixed where they cost you users and revenue.
Modernise legacy apps
Turn a codebase that fights your team into one that ships fast again — without a doomed rewrite.
Design scalable architecture
Clear boundaries so multiple engineers ship in parallel without stepping on each other.
Lead Flutter & Android migrations
Staged, reversible migrations (MVP→MVVM, XML→Compose) proven in production, not on a whiteboard.
Build reusable SDKs
Developer-facing SDKs that are stable, ergonomic, and fast for other teams to adopt.
Mentor & level up teams
Review culture, testing, and delivery practices that cut defects and raise velocity for good.
How I help
Consulting, scoped to outcomes.
Focused engagements, each tied to a real problem and a measurable result — from a one-off architecture review to an ongoing fractional mobile lead.
Mobile Architecture Review
A structured audit of your Flutter or Android codebase, and a written plan: the risks that matter, in priority order.
Performance Optimisation
Cold start, jank, memory, app size, and crashes — profiled on real devices and prioritised by user and revenue impact.
Flutter Rescue & Legacy Modernisation
Stabilise an inherited or stalled app, cut the worst debt, and give the team a credible path forward.
Fractional Mobile Lead
Senior mobile technical direction a few days a month for teams without a full-time lead.
SDK Development
Design and build developer-facing SDKs that are stable, backward-compatible, and fast to integrate.
Engineering Mentoring & Code Audits
Architecture, review, and testing practices — transferred to your team so they outlast the engagement.
Selected case studies
Engineering write-ups, not portfolio cards.
Experience
A decade of ownership and impact.
Beyond One
Senior Mobile Engineer
Oct 2025 — Present
- Own Flutter delivery on a global eSIM platform used across 190+ countries.
- Lifted free-to-paid conversion 20% by diagnosing and fixing subscription-flow defects — directly growing recurring revenue.
ZealTouch
Lead Flutter Developer
Dec 2024 — Oct 2025
- Led a cross-functional team building a community marketplace across Australia.
- Reduced production defects 50% and raised team velocity 25% by introducing review, testing, and estimation discipline.
Amity Technologies · Social+
Senior Flutter Engineer
Feb 2023 — Oct 2024
- Owned a developer-facing Flutter SDK embedded in third-party apps worldwide.
- Closed the native/Flutter feature-parity gap from 50% to 25%, unblocking real client use cases.
Systems Limited
Senior Android Consultant
Oct 2021 — Jan 2023
- Drove architecture modernisation for a lifestyle & rewards platform serving 1M+ users.
- Led 90% MVP→MVVM and 70% XML→Jetpack Compose migrations, cutting boilerplate ~40%.
Featured testimonials
Featured testimonials
It was a real pleasure having Umar on the team. He worked with honesty and dedication, and always went out of his way to over-deliver regardless of the circumstances. He was someone we could always rely on — even against short deadlines, he stepped up and helped us commit and get things done. A great team player with solid technical understanding, he handled new technologies and challenges with confidence every time. And he left a real legacy behind: the successors he hired are still with us five years later and have helped the team grow further. Any team would be lucky to have him.
More client feedback
Reliable, technically strong, easy to work with.
“Muhammad Umar is one of the best Android developers I've worked with. He maintains high professional standards, communicates clearly, takes ownership of every task, and delivers reliable, high-quality work. He's become my go-to for Android and Kotlin — I wouldn't hesitate to hire him again.”
“A highly professional and reliable developer who delivered exactly what was needed. Great communication, excellent technical skills, and a pleasure to work with. I highly recommend him.”
“Umar handled specialised Android integrations with great professionalism and problem-solving skills. Even when unexpected challenges arose, he stayed committed to delivering quality. Technically strong, communicates well, and someone I'd confidently recommend.”
“An exceptionally talented developer who delivered exactly what I needed — one of the best experiences I've had working with a developer.”
“One of the best I have worked with — dependable, highly skilled, and always willing to go the extra mile to solve any challenge. I highly recommend working with him.”
Articles
Notes on mobile performance & architecture.
Your App Shouldn't Need to Know Everything That Happens
Event-driven communication in Flutter and Android isn't really about sending events. It's about letting the right parts of an app react to change without knowing too much about each other — and knowing when a global event bus is the wrong tool.
Why your app's cold start is quietly costing you users
The users you lose to a slow launch never complain — they just don't come back. A practical guide to measuring cold start, finding where the time goes, and getting it back.
The most expensive bug doesn't crash anything
When a revenue flow breaks, it usually breaks quietly — no error, no ticket, just a number that's lower than it should be. That's where the money hides.
About
Most mobile problems are architecture problems wearing a performance costume.
Fast, stable, maintainable apps come from clear boundaries, measured decisions, and product thinking — not clever one-off fixes. That's the lens I bring to every engagement, and why teams keep me around to help them scale rather than firefight.
Need help scaling your mobile app?
Book a short consultation. We'll talk through what's happening and whether I'm the right person to help.