Muhammad is available for hire

Muhammad AbuBakar Siddiq

Verified Expert in Engineering

Mobile Developer

Lahore, Punjab, Pakistan

Toptal member since July 12, 2022

Expertise

Android Coding Debugging Mobile App API Integration DNS Code Review POS Full-stack Java

Bio

Muhammad is a senior fintech and mobile engineer with 8+ years of experience building production-grade Android, iOS, and React Native apps for startups and enterprises across the US, EU, UAE, and Australia. He specializes in payment systems, BLE hardware integrations, and offline-first architectures. He built a POS system that processed AUD 1.5+ million across 100+ devices in 10 days—with zero failures. Muhammad uses AI tooling to ship faster without cutting corners.

Portfolio

Journey - Main

Kotlin, Android, Strapi, Android SDK, Android Jetpack, RESTFul APIs...

Sendrato Australia PTY LTD

Android, Kotlin, API Integration, Integration, RFID, Serial Communication...

Evento Solutions

Android Development, Model View ViewModel (MVVM), Kotlin, Java, OneSignal...

Experience

Mobile App Development - 8 years
Java - 8 years
Android Development - 8 years
Kotlin - 7 years
Swift - 3 years
iOS - 3 years
REST APIs - 3 years
Node.js - 3 years

Preferred Environment

Windows, MacOS, Slack, Android Studio, Xcode, WebStorm, Jira, Trello, Bitbucket, ClickUp

The most amazing...

...thing I've built is an Android POS that processed AUD 1.5+ million via Stripe Terminal on 100+ devices with RFID and cash acceptor integration.

Work Experience

Senior Mobile Engineer (Android, IOS, KMM, and React Native)

2025 - 2026

Journey - Main

Improved app performance by optimizing rendering, API handling, and state management, resulting in smoother user experience across key flows.
Led the development of the Discover page, implementing feed-based UI, filtering, and map-based exploration for enhanced user engagement.
Implemented scalable analytics architecture using HighTouch and Customer.io, improving event tracking consistency and product insights.
Worked on Kotlin Multiplatform (KMM) layer to support shared business logic and improve code reusability across platforms.
Contributed to migration from native Android and iOS to React Native, enabling faster cross-platform delivery and reducing development overhead.
Integrated authentication, push notifications, and third-party services (Clerk and Customer.io) to ensure secure and reliable user engagement.
Collaborated with cross-functional teams to deliver production-ready features under tight timelines in a fast-paced environment.

Technologies: Kotlin, Android, Strapi, Android SDK, Android Jetpack, RESTFul APIs, React Native, Clerk, Analytics, Customer.io, Kotlin Multiplatform, Kotlin Multiplatform Mobile (KMM), iOS, Mapbox, CI/CD Pipelines, CIO, GitHub Actions, Model View ViewModel (MVVM), KOIN, App Store Connect, App Submission, Google Play Console, Deep Linking, Push Notifications, Booking, AI Tools, Claude Code, Full-stack, Web Development, GPS, Low-code Development, Developer Relations, Full-stack Development, Continuous Delivery (CD), Continuous Integration (CI), Code Auditing, Mobile UI Design, TestFlight, iOS App Development, Application Architecture, Firebase Realtime Database, Cloud, Mobile Architecture, API Development, Authorization, App Development, Artificial Intelligence (AI), User Interface (UI), User Experience (UX), Figma, Pixel Perfect, Design, Coding, Geolocation, Claude, Room, Mobile Back-end, Code Review

Android Integration Engineer

2025 - 2025

Sendrato Australia PTY LTD

Developed a multi-terminal Android POS system supporting Sunmi K2, D3, and Zebra CC6000, with seamless hardware integration including RFID card issuance and Stripe Terminal-based Tap-to-Pay functionality.
Implemented a payment workflow integrating a POS server and Stripe payment, supporting both manual and automatic capture, offline transaction queuing, and error recovery.
Deployed the POS system for a high-traffic event, processing over 1.5 million AUD in transactions within 10 days, demonstrating the system’s stability, performance, and real-world scalability.

Technologies: Android, Kotlin, API Integration, Integration, RFID, Serial Communication, Universal Asynchronous Receiver/Transmitter (UART), CCITT High Level Language (CHILL), Stripe Payments, POS, Stripe Terminal, Digital Payments, Fintech, Payment Gateways, Payment Processing, Fintech Consultant, Apps, Performance Optimization, Concurrency, GitHub Actions, App Store Connect, DevOps, Payment APIs, Payments, Stripe API, Consumer to Consumer (C2C), Prepaid Debit Cards, Stripe Connect, AI Tools, Claude Code, Continuous Delivery (CD), Continuous Integration (CI), Code Auditing, Mobile UI Design, Firebase Realtime Database, Mobile Architecture, Authorization, App Development, User Interface (UI), User Experience (UX), Figma, Pixel Perfect, Design, Stripe Connect API, Coding, Claude, Room, Security

Senior Android Developer

2023 - 2025

Evento Solutions

Spearheaded development of event apps for major international conferences in Dubai and KSA, serving thousands of live attendees.
Integrated AR-based venue navigation, enabling real-time exploration of large event venues and significantly enhancing attendee experience.
Engineered real-time in-app networking — chat, meetup requests, and interactive table arrangements — driving engagement across multi-day events.
Implemented role-based access control and digital guest management, replacing manual entry verification across restricted event zones.
Delivered full-featured apps end-to-end — agendas, speaker profiles, sponsor directories, and participant lists — for 4 high-profile international summits.
Maintained zero-downtime production stability across live events with thousands of concurrent users in the UAE and Saudi Arabia.

Technologies: Android Development, Model View ViewModel (MVVM), Kotlin, Java, OneSignal, Firebase, Deployment, WebView, React Native, Expo, Videos, Healthcare, Android Architecture, Android Studio, Jetpack Compose, Hilt, Apps, Authentication, Google Login, Concurrency, GitHub Actions, App Store Connect, SwiftUI, Fastlane, Payment APIs, Payments, Stripe API, Consumer to Consumer (C2C), MVP Design, Two-factor Authentication (2FA), Replit, AI Tools, Apple Pay, AI Chatbots, Continuous Delivery (CD), Continuous Integration (CI), Code Auditing, MongoDB, Mobile UI Design, TestFlight, LLM Integration, Wearables, iOS App Development, Application Architecture, Firebase Realtime Database, Data Migration, Cloud, Subscriptions, Mobile Architecture, GoDaddy, AI Integration, API Development, Dashboards, Authorization, Role-based Access Control (RBAC), App Development, User Interface (UI), Figma, Pixel Perfect, Design, App Design, Coding, Geolocation, Room, Next.js, Mobile Back-end

Mobile Team Lead

2023 - 2023

Enjoy Deals Marketing Ltd

Led development of the Enjoy app from zero to live on both the Play Store and App Store within an 8-month contract in Dubai.
Managed a cross-platform mobile team of 3 engineers — Android and 2 iOS developers — owning architecture, code reviews, and delivery accountability.
Engineered a location-based vendor discovery system with geo-filtered search, preference-based filtering, and real-time coupon redemption.
Implemented subscription payment flows using credit/debit cards, enabling users to access BOGO, percentage discount, and complimentary vendor offers.
Built a vendor-facing management portal allowing vendors to independently create, manage, and track offer performance, reducing operational overhead.
Developed mobile APIs in Node.js, owning both client and server side for tight integration and fast iteration without back-end dependency bottlenecks.
Architected the full app from scratch using MVVM and clean architecture principles, ensuring scalability and maintainability across Android and iOS.

Technologies: Android, iOS, APIs, REST APIs, Node.js, REST, Google Play Store, API Integration, GitHub, Minimum Viable Product (MVP), Balsamiq, JavaScript, Mobile Applications, App Submission, Express.js, Software Architecture, Deployment, Android Architecture, Android Studio, Apps, Authentication, Google Login, Concurrency, App Store Connect, Payment APIs, Payments, Stripe API, TypeScript, Consulting, Consumer to Consumer (C2C), Booking, MVP Design, Marketplaces, Stripe Connect, User Roles, Vercel, iOS App Development, Application Architecture, Firebase Realtime Database, Cloud, Subscriptions, Mobile Architecture, DNS, GoDaddy, Email, API Development, Authorization, App Development, Figma, Pixel Perfect, Design, Stripe Connect API, Coding, Geolocation, Room, Mobile Back-end

Mobile Team Lead

2021 - 2023

E2E Solution Providers

Led mobile architecture and engineering across two major product lines simultaneously — an enterprise field ops platform for Nestlé Pakistan and a sports management app.
Architected and delivered a real-time field monitoring app for Nestlé Pakistan, enabling automated reporting and live progress tracking across nationwide brand activation campaigns.
Designed the full mobile architecture end-to-end — from system design through delivery — for one of Pakistan's largest FMCG enterprises.
Led development of GemGolfer, a tournament and handicap management app implementing World Handicap System (WHS) calculations — one of the few apps globally to do so.
Delivered features covering tournament management, league tracking, tours, daily rounds, and WHS-compliant handicap calculation for competitive golfers.
Deployed GemGolfer to real-name clients, including Karachi Golf Club, Gym Khana Golf Club, and Challenger League — production software used in live competitive events.
Supervised and mentored the mobile development team, conducting code reviews, enforcing architectural standards, and ensuring delivery quality across sprints.

Technologies: Android, iOS, Mobile App Development, Swift, Java, Kotlin, Node.js, REST APIs, Android Development, GraphQL, Dagger 2, RxJava, Coroutines, Android SDK, RoomDB, Model View ViewModel (MVVM), Retrofit, Android Jetpack, Firebase, Apollo, Hasura, Heroku, Google In-app Billing, Back-end, Back-end Development, JSON, APIs, Git, Push Notifications, Android UI Design, Google Maps, Maps, XML, Card Payments, Gradle, Navigation, Mobile Development, Mobile, Dependency Injection, User Experience (UX), User Interface (UI), Debugging, Mobile Apps, Mobile GPS, Clean Code, Dagger, OkHttp, UI Testing, REST, Location Services and Maps, Google Maps API, App Store, Google Play Store, Software as a Service (SaaS), API Integration, GitHub, RTL, Localization, Internationalization, Balsamiq, Cloud Firestore, Google Pay, JavaScript, Amazon Web Services (AWS), Mobile Applications, App Submission, Deployment, WebView, Testing, Reactive Programming, Android Architecture, Android Studio, Apps, Google Login, Concurrency, App Store Connect, Payment APIs, Payments, Stripe API, TypeScript, Consumer to Consumer (C2C), PostgreSQL, WatchOS, Apple HealthKit, Tracking, iOS App Development, Application Architecture, Firebase Realtime Database, React, Subscriptions, Mobile Architecture, StoreKit 2, GoDaddy, Email, API Development, Authorization, App Development, Pixel Perfect, Design, Room

Mobile Application Developer

2019 - 2021

Halim Solutions

Designed, architected, and developed an Uber-style on-demand platform for cargo, towing trucks, water tankers, and waste tankers — built for both Android and iOS.
Built an encrypted BLE mobile application communicating with Raspberry Pi hardware to command Axis access controllers for wireless door lock/unlock across enterprise premises.
Implemented rotating-key BLE encryption architecture, ensuring all device-to-mobile communication was tamper-proof and resistant to replay attacks.
Engineered hardware tamper detection logic that immediately blocked all Axis controller communication upon any physical or code-level device tampering.
Developed multiple NFC tag scanning systems for labor access management across secure facilities, including role-based access, entry logging, and zone restrictions.
Built a live field operations app for security teams with real-time GPS tracking, patrol monitoring, and checkpoint verification across guard routes.
Contributed to a document expiry reminder iOS app, helping users avoid penalties from expired official documents through timely automated notifications.

Technologies: Android, iOS, Mobile App Development, Kotlin, Java, Swift, Android Development, Bluetooth Low Energy (LE), RxJava, Coroutines, Android SDK, RoomDB, Model View ViewModel (MVVM), Retrofit, Android Jetpack, Firebase, Stripe Payments, Unit Testing, JSON, APIs, Bluetooth, Engineering, Git, Model View Presenter (MVP), Model View Controller (MVC), Location Services, Push Notifications, WebSockets, Android UI Design, Google Maps, Maps, PHP, XML, Card Payments, Gradle, Navigation, Mobile Development, SQL, MySQL, Mobile, Stripe, Near-field Communication (NFC), Debugging, Internet of Things (IoT), Hardware, Mobile Apps, Mobile GPS, Clean Code, OkHttp, REST, Location Services and Maps, Google Maps API, Real-time Data, App Store, Google Play Store, RFID, API Integration, GitHub, RTL, Localization, Internationalization, Balsamiq, Cloud Firestore, Mobile Applications, App Submission, Deployment, WebView, Testing, Reactive Programming, Android Studio, Apps, Concurrency, App Store Connect, Stripe API, Consumer to Consumer (C2C), MVP Design, Stripe Connect, Socket.IO, GPS, Firebase Realtime Database, Mobile Architecture, Audio Engines, StoreKit 2, Twilio API, Role-based Access Control (RBAC), App Development, Pixel Perfect, Design, Google API, Geolocation

Android Application Developer

2018 - 2019

Black Storm Technologies

Managed product development of an in-house event feedback and reviews Android application from concept through deployment.
Developed LifeBrary, an Android app built in Kotlin, enabling users to track and document personal life events with images and timestamps.
Restructured and extended a live lecture platform, enabling lecturers to record, publish, and stream live lessons to a remote audience.
Integrated real-time communication features using QuickBlox and SendBird SDKs to enable live in-app chat and audience interaction.
Delivered multiple production Android applications using MVVM architecture, Firebase, and Retrofit, maintaining clean code standards throughout.

Technologies: Software, Android Development, Android SDK, Model View ViewModel (MVVM), Retrofit, Firebase, JSON, APIs, Push Notifications, XML, Gradle, Mobile Development, Mobile, QuickBlox, SendBird, Debugging, Mobile Apps, Clean Code, OkHttp, REST, App Store, Google Play Store, API Integration, GitHub, Mobile Applications, App Submission, Android Studio, Consumer to Consumer (C2C)

Experience

Android POS Terminal with Stripe Integration & Offline Smart Card Processing

Developed a production-grade Android POS terminal application for retail/fintech environments, focused on secure payments, offline reliability, and hardware integrations.

Integrated Stripe Terminal for in-person card payments on POS and KIOSK, and implemented custom Fun Card (RFID/Smart Card) integration for stored-value transactions. Designed and built a robust offline handling system to support low-connectivity environments by caching SKUs and enabling offline transactions.

Key contributions included:
• Stripe Terminal SDK integration for secure card-present payments on POS terminal and KIOSK
• RFID/Fun Card balance check, charge, and reconciliation flow
• Offline SKU caching for product catalog in low-network areas
• Offline Fun Card charging with queued transactions
• Intelligent sync mechanism (sync points) triggered on network availability
• Error handling, retry strategies, and transaction integrity safeguards

The solution ensured uninterrupted operations in poor network zones while maintaining transaction consistency and secure financial processing.

The Android POS and KIOSK processed AUD 1.5+ million via Stripe on 100+ devices in 10 days at the Sydney Royal Easter Show 2025.

Travel Rewards & Booking Platform

Contributed as part of a large cross-functional engineering team building and evolving a consumer travel rewards platform that enables users to discover properties, book stays, and earn loyalty points.

Initially worked on the native mobile applications (Android and iOS) and participated in architectural improvements using Kotlin Multiplatform (KMP) to share business logic across platforms. Later contributed to the full mobile rewrite and migration to React Native to enable faster feature development and a unified cross-platform codebase.

Worked on key features including property discovery, search and filtering, map-based browsing, booking flows, and rewards tracking. Collaborated with back-end, product, and analytics teams to optimize API payloads, improve mobile performance, and support scalable high-traffic usage.

14th World Islamic Economic Forum Event App

Contributed to the development of the 14th World Islamic Economic Forum Event App, offering participants easy access to event details, program descriptions, and speaker information. Implemented networking features such as meetup scheduling and interactive table arrangements to foster connections among attendees. Elevated event engagement and participant experience through intuitive design and functionality.

Global Industrial Internet of Things Summit Event App

Developed a comprehensive event app for the Global Industrial Internet of Things Summit in KSA. This app served as a digital guide, providing attendees with event schedules, speaker bios, sponsor information, and venue maps. Integrated innovative AR navigation for seamless venue exploration and enhanced user experience.

GemGolfer Mobile Application for Golfers

GemGolfer is an app for golfers to manage tournaments, leagues, tours, daily rounds, and handicaps. It is one of the few apps with handicaps based on the World Handicap System. Some of the leading users of the GemGolfer app are Karachi Golf Club, Gym Khana Golf Club, and Challenger League.

Nestlé Brand Activation Application

An Android-based mobile application for Nestlé, focusing on Nestlé brand activation, real-time monitoring, keeping track of all the progress, and automated reporting of ground activities.

I was in charge of developing a mobile application while coordinating with the back-end team.

Mi-Key

Quanika is an access control solution deployed at many buildings in the US and UAE. It gives access to a door to the visitors using RFID. Mi-Key is an extended integration with Quanika, enabling users to access doors using Bluetooth with mobile phones.

PickUpOO

PickUpOO is a solution for cargo, towing trucks, water tankers, and waste tankers. Booking these services is similar to the Uber app—users select a service and choose pick-up location and destination while the service provider receives and completes the order.

The application is built for both Android and iOS users. The user can track the driver using Google Maps and a socket connection at any point.

ExpReminder

ExpReminder is a simple application specially designed to remind users of the expiry dates of their important documents on time. The app intends to assist users in taking the appropriate action before the important and official documents expire. As a result, the user may avoid any penalty or travel delay caused by expired documents.

The application is developed for iOS users.

Education

2014 - 2018

Bachelor's Degree in Software Engineering

The University of Lahore - Lahore, Pakistan

Certifications

JULY 2023 - PRESENT

Master CI/CD for Android Developers

Udemy

MAY 2023 - PRESENT

Jetpack Compose Crash course for Android with Kotlin

Udemy

MAY 2022 - PRESENT

Silver Award Fury Road

Codility

JANUARY 2022 - PRESENT

Android Dependency Injection with Dagger 2 and Kotlin

Skills

Libraries/APIs

Retrofit, Google Maps, Stripe API, Stripe Connect, API Development, Google API, Node.js, REST APIs, Stripe, Google Maps API, Socket.IO, Twilio API, Stripe Connect API, RxJava, SendBird, QuickBlox, Auth, Google Places API, React

Tools

Android Studio, Android Jetpack, GitHub, WebView, Apple HealthKit, Figma, Claude, Git, Gradle, Expo, Fastlane, Claude Code, TestFlight, Skype, Slack, Xcode, WebStorm, Jira, Trello, Bitbucket, Balsamiq, OneSignal, Google Places SDK

Languages

Kotlin, Java, Swift, GraphQL, XML, JavaScript, TypeScript, PHP, SQL, CCITT High Level Language (CHILL)

Frameworks

Android SDK, Express.js, React Native, SwiftUI, StoreKit 2, Dagger 2, Dagger, KOIN, Next.js

Paradigms

Model View ViewModel (MVVM), Mobile Development, Clean Code, REST, DevOps, Continuous Delivery (CD), Continuous Integration (CI), Application Architecture, Role-based Access Control (RBAC), App Development, Reactive Programming, API Architecture, Low-code Development, Mobile UI Design, UX Design, UI Design, Design Patterns, Dependency Injection, Unit Testing, Model View Presenter (MVP), Model View Controller (MVC), Object-oriented Programming (OOP), Testing

Platforms

Android, iOS, Firebase, Heroku, Mobile, Amazon Web Services (AWS), WatchOS, Bluetooth Low Energy (LE), Replit, Vercel, Windows, MacOS, Clerk, Mapbox

Storage

Hasura, JSON, Firebase Realtime Database, RoomDB, Cloud Firestore, PostgreSQL, MongoDB, MySQL

Industry Expertise

Healthcare

Other

Mobile App Development, Android Development, Apollo, APIs, Push Notifications, Maps, User Experience (UX), User Interface (UI), Card Payments, Navigation, Debugging, Architecture, Mobile Apps, Mobile GPS, App Store, Google Play Store, API Integration, RTL, Localization, Internationalization, Minimum Viable Product (MVP), CI/CD Pipelines, Mobile Applications, Jetpack Compose, App Submission, Deployment, Android Architecture, Integration, POS, Payment Gateways, SDKs, API Testing, API Design, Apps, Authentication, Google Login, Performance Optimization, Concurrency, GitHub Actions, App Store Connect, Payment APIs, Payments, Consulting, Consumer to Consumer (C2C), Prepaid Debit Cards, MVP Design, Full-stack, GPS, Code Auditing, Subscriptions, DNS, GoDaddy, Email, Authorization, Pixel Perfect, Design, App Design, Coding, Geolocation, Room, Mobile Back-end, Code Review, Coroutines, Stripe Payments, Google In-app Billing, Back-end, Bluetooth, Location Services, WebSockets, Android UI Design, Near-field Communication (NFC), Internet of Things (IoT), Hardware, OkHttp, Location Services and Maps, RFID, Google Pay, Software Architecture, Live Chat, Videos, Hilt, Fintech, Payment Processing, Fintech Consultant, Kotlin Multiplatform, Kotlin Multiplatform Mobile (KMM), Booking, Marketplaces, Two-factor Authentication (2FA), User Roles, AI Tools, Developer Relations, Full-stack Development, Apple Pay, AI Chatbots, Wireless Protocols, Tracking, LLM Integration, Wearables, iOS App Development, Data Migration, Cloud, Mobile Architecture, AI Integration, Dashboards, Artificial Intelligence (AI), Security, Software Development, Quality Assurance (QA), Software, Complex Problem Solving, Back-end Development, Engineering, UI Testing, Real-time Data, Software as a Service (SaaS), Analytics, Serial Communication, Universal Asynchronous Receiver/Transmitter (UART), Stripe Terminal, Digital Payments, ClickUp, Offline-first Architecture, Strapi, HighTouch, Customer.io, RESTFul APIs, CIO, Google Play Console, Deep Linking, Web Development, Audio Engines

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