John is available for hire
Hire JohnJohn Ernest Guadalupe
Verified Expert in Engineering
Android Developer
Santo Tomas, Calabarzon, Philippines
Toptal member since December 18, 2015
Bio
John is a results-driven professional with a strong focus on value. He collaborates closely with clients to develop user-friendly products that fulfill business objectives. His passion lies in bringing innovative, market-disrupting ideas to life, and he is adept at delivering business-specific solutions that meet the highest standards.
Portfolio
EY
React Native, Kotlin, Android, AngularJS, Xamarin.Forms, Microsoft SQL Server...
Freelance Work
Android, Technical Leadership, Android SDK, Kotlin, RxAndroid, C#, GraphQL...
Orion180 Insurance Services LLC
Xamarin, .NET, C#, JavaScript, HTML, CSS, Databases, Mobile UI, Full-stack, SQL...
Experience
Availability
Full-time
Preferred Environment
Android Studio, Visual Studio, Visual Studio Code (VS Code), Azure, Firebase, Amazon Web Services (AWS), Google Cloud
The most amazing...
...project I've handled is a super app that has food deliveries, medicine, and an integrated online wallet feature. I led an IT team to launch the project.
Work Experience
Associate Manager
2020 - PRESENT
EY
- Guided clients on the technical aspects of their projects.
- Assisted teams in multiple mobile projects, being the lead developer on several projects.
- Developed software for multiple projects spanning mobile and web technologies.
- Served as a full-stack developer building mobile and web applications. I also maintained existing apps for bug fixes and new feature integration.
Technologies: React Native, Kotlin, Android, AngularJS, Xamarin.Forms, Microsoft SQL Server, Azure, .NET, Android SDK, RxAndroid, C#, Xamarin, Technical Leadership, Software Architecture, Google API, SourceTree, Retrofit 2, RxJava, React, Firebase, TypeScript, API Integration, Chatbots, UI Design, UX Design, Mobile Apps, APIs, Design, Expo, Google Play Console, Geolocation, Testing, Security, JSON, Spring Boot, Mobile Development, MySQL, HTML5, WebView, Amazon Web Services (AWS), .NET MAUI, User Experience (UX), User Interface (UI), Angular, App Store, Google Play Store, Authentication, Clean Code, IT Project Management, IT Projects, Audio, Speech to Text, Text to Speech (TTS), Architecture, Full-stack Development, Web Applications, Biometrics, Cross-platform App Development, Cloud Deployment, Firebase Authentication, Object-oriented Programming (OOP), Linux, Image Processing, Artificial Intelligence (AI), Machine Learning, Android Studio, Web Development, Mobile, Next.js, Progressive Web Applications (PWAs), Redux, CI/CD Pipelines, Xcode
Software Architect and Lead Developer
2013 - PRESENT
Freelance Work
- Developed applications from the ground up, following the appropriate methodologies for software development for corporate and public use.
- Studied and implemented different paradigms as case studies for different projects to know the best ones for different niches.
- Utilized multiple leading technologies for features such as location, maps, payments, user experience, analytics, and behavior patterns.
- Led teams, set project deadlines, and worked as part of teams for different projects.
- Used Google Sheets, Docs, and Slides to keep teams on track.
- Communicated directly and promptly with the client about any concerns regarding the project.
- Implemented Material Design principles on different projects.
Technologies: Android, Technical Leadership, Android SDK, Kotlin, RxAndroid, C#, GraphQL, Software Architecture, Google API, Firebase Realtime Database, SourceTree, Retrofit 2, RxJava, Cloud Firestore, Xamarin, React, React Native, Node.js, TypeScript, API Integration, UI Design, UX Design, Mobile Apps, APIs, Design, Google Play Console, Geolocation, Stripe API, Testing, Security, JSON, Mobile Development, HTML5, WebView, Algolia, User Experience (UX), User Interface (UI), App Store, Google Play Store, Authentication, React Native Navigation, Clean Code, IT Project Management, IT Projects, Speech to Text, Text to Speech (TTS), Architecture, Full-stack Development, Web Applications, Biometrics, Cross-platform App Development, Firebase Authentication, Object-oriented Programming (OOP), Image Processing, Android Studio, Web Development, Mobile, Progressive Web Applications (PWAs), Redux, CI/CD Pipelines, Xcode
Hybrid Mobile Insurance Application Developer
2021 - 2024
Orion180 Insurance Services LLC
- Led the development of an application by integrating features from the web app using the same back-end infrastructure.
- Implemented user interface designs utilizing Xamarin Forms and .NET MAUI. Tailored controls and views to meet specific platform requirements. Adapted behaviors and interfaces for the implementation of features.
- Maintained the application by resolving bugs, making necessary adjustments, and incorporating new features as dictated by business requirements and operational continuity.
Technologies: Xamarin, .NET, C#, JavaScript, HTML, CSS, Databases, Mobile UI, Full-stack, SQL, Azure, Bootstrap, Vue, REST APIs, SourceTree, API Integration, UI Design, UX Design, Mobile Apps, APIs, Design, .NET MAUI, Google Play Console, Testing, Security, JSON, Mobile Development, WebView, User Experience (UX), User Interface (UI), App Store, Google Play Store, Authentication, Clean Code, IT Projects, Architecture, Biometrics, Cross-platform App Development, Object-oriented Programming (OOP), Android Studio, Mobile, CI/CD Pipelines, Xcode
Mobile Developer
2022 - 2023
10 Gears LLC
- Implemented a new server instance with automated publishing of the back-end server from a GitHub Action.
- Managed Android and iOS mobile apps and admin web app code repositories for new feature implementations.
- Led and integrated new database instances for the revamped back end.
Technologies: iOS, Mobile Payments, Android, Swift, Java, Kotlin, Android SDK, iOS SDK, React, Express.js, Node.js, GitHub, API Integration, Mobile Apps, Google Play Console, Geolocation, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Architecture, Object-oriented Programming (OOP), Android Studio, Web Development, Mobile, Xcode
Senior Native (Apple and Android) Developer
2022 - 2022
Imagemakers Inc.
- Used Jira software for tracking tickets and maintaining applications by fixing bugs, adjusting behaviors, and fixing layouts.
- Utilized JavaScript in analyzing and mitigating bugs on the web app.
- Monitored the application performance, adjusting variables and logic as necessary.
Technologies: Android, iOS, Swift, Java, JavaScript, PostgreSQL, jQuery, Vanilla JS, Google API, SourceTree, API Integration, Mobile Apps, Google Play Console, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Object-oriented Programming (OOP), Android Studio, Web Development, Mobile, Xcode
Senior Mobile Developer
2018 - 2020
Navitaire Philippines, Inc. (via NTT Data Philippines)
- Maintained existing airline applications for customers developed using Xamarin Forms.
- Fixed bugs on both Android and iOS platforms using C#.
- Developed new features involving RESTful services, Xamarin Forms, and C#.
Technologies: GraphQL, Android, C#, Xamarin, Android SDK, Kotlin, Xamarin.Forms, Technical Leadership, Software Architecture, Google API, SourceTree, API Integration, Mobile Apps, Google Play Console, Geolocation, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Object-oriented Programming (OOP), Android Studio, Mobile, Xcode
Senior Android Developer
2016 - 2018
Inovotek Apps, Inc.
- Led the Android team in the implementation of new features to existing projects.
- Maintained existing projects, including handling release and bug monitoring.
- Discussed and implemented the architecture foundations for projects with iOS, web, and design team leaders.
Technologies: Crashlytics, Jira, Bitbucket, Technical Leadership, Android, Java, Android SDK, Kotlin, RxAndroid, Software Architecture, Google API, Firebase Realtime Database, SourceTree, Retrofit 2, RxJava, Cloud Firestore, API Integration, Mobile Apps, Google Play Console, Geolocation, Stripe API, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Object-oriented Programming (OOP), Android Studio, Mobile
Senior Android Developer
2016 - 2016
Samsung Mobile R&D Philippines
- Spearheaded the Espresso implementation in projects.
- Maintained existing applications by fixing bugs, adjustments, and aesthetics.
- Implemented new features such as email automation on mobile apps and recognition of content.
Technologies: Jira, GitHub, Spoon Testing, Espresso, Eclipse, Xamarin, Android, Java, Android SDK, Software Architecture, SourceTree, RxJava, API Integration, Mobile Apps, Google Play Console, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Object-oriented Programming (OOP), Android Studio, Mobile
Software Developer
2013 - 2016
KLab Cyscorpions, Inc.
- Developed new features on existing apps. Maintained applications by adding new modules on existing features and/or creating a new module from scratch.
- Resolved app issues by utilizing issue-tracking technologies.
- Code-reviewed pull requests to maintain the quality of code.
- Pioneered the usage and development of a unit testing framework using Robotium.
- Supported, taught, and led junior developers with multiple tasks.
- Helped with improvement and implementation of the current workflow.
Technologies: Spoon Testing, GitHub, Robotium, Eclipse, Android, Java, Android SDK, Software Architecture, Firebase Realtime Database, SourceTree, Retrofit 2, RxJava, API Integration, Mobile Apps, Google Play Console, Testing, JSON, Mobile Development, App Store, Google Play Store, Authentication, Clean Code, Object-oriented Programming (OOP), Android Studio, Mobile
Experience
Basketball League Application
A React Native-based application that aims to make the organization and completion of leagues between teams with small to medium followings in neighborhoods easier and more secure. Features include the creation of leagues with maps, location setting, player selection, contract creation and bet holding and assistance, and team management.
Vehicle Dealership Management App
A React Native application that is based on an existing web application used to manage the inventory and business of dealerships across the US. Features include VIN code scanning and OCR, inventory management, listing management, and more
NFTApp
An app focusing on delivering analytics on NFTs based on different sources such as Icy.tools, NFTPort, and others. I collected data and created an attractive UI for displaying data on charts and bar charts. I also provided predictions for proper NFT staking, buying, and selling.
Guapp
A delivery platform where users can order from markets, restaurants, pharmacies, and other store categories. It utilizes Google Maps for location features and has an intuitive design that appeals to the younger market.
I have led the software development team in this project, managing at most 10 people comprised of Android, iOS, and web developers, as well as QA engineers and business analysts. We have used Firebase for the authentication, database, hosting, and analytics. We have also used Stripe for the payments.
I have also led the development of the Android app utilizing Kotlin. I have used the MVVMC architecture using Conductor for the controller and navigation stack, Dagger for dependency injection, Kotlin Coroutines for multi-threading, and Android architecture components such as ViewModel and LiveData.
I have led the software development team in this project, managing at most 10 people comprised of Android, iOS, and web developers, as well as QA engineers and business analysts. We have used Firebase for the authentication, database, hosting, and analytics. We have also used Stripe for the payments.
I have also led the development of the Android app utilizing Kotlin. I have used the MVVMC architecture using Conductor for the controller and navigation stack, Dagger for dependency injection, Kotlin Coroutines for multi-threading, and Android architecture components such as ViewModel and LiveData.
Tarjemle | Translation Services
I led the development of this platform for translators. With agile practices already in place, I planned the architecture and development schedule of multiple web portals and Android and iOS applications, as well as landing pages and back-end servers.
I also personally developed the Android application for customers and translators here, wherein they can have documents analyzed and have words automatically counted.
Translators can accept and decline tasks. Both the customers and translators can coordinate with account managers for the tasks and results through the chat module (that we developed). We used Firebase Firestore for the applications' back end.
I also personally developed the Android application for customers and translators here, wherein they can have documents analyzed and have words automatically counted.
Translators can accept and decline tasks. Both the customers and translators can coordinate with account managers for the tasks and results through the chat module (that we developed). We used Firebase Firestore for the applications' back end.
Pulire | Shoe Cleaning Service
Pulire is a service to have all kinds of shoes cleaned. It has a menu for the services you can avail of and where you'd like the shoes picked up and delivered. It has a partner app for its couriers, which I also developed. I collaborated with a team I have handpicked to create a working, commercial system complete with an admin portal.
The customer can create an order to upload pictures of a pair of shoes that need servicing and the specific services he wants. After the shop's couriers are notified and accept the pickup request, the app gives them the customer's location. The couriers then collect the items and payments. Once the shoes have arrived at the store, an admin monitors the cleaning process, prompts user updates, and users get notified through push notification. After the service is completed, the shoes will be delivered back to the customer.
The customer can create an order to upload pictures of a pair of shoes that need servicing and the specific services he wants. After the shop's couriers are notified and accept the pickup request, the app gives them the customer's location. The couriers then collect the items and payments. Once the shoes have arrived at the store, an admin monitors the cleaning process, prompts user updates, and users get notified through push notification. After the service is completed, the shoes will be delivered back to the customer.
PharmacyDirect | A Medicine Delivery System
https://goo.gl/xw44jcWith one of my developer friends, we created a suite of applications for a company that delivers medicine to people in South Africa.
I created the client and the delivery personnel applications.
The client application allows users to upload prescriptions and update them about concerning their deliveries, which are automatically managed by the system. It also shows them the current location of the personnel that is delivering the medicine.
For the delivery personnel app, it was designed to give the users notifications when a delivery is assigned to them as well as show the location of the client.
I created the client and the delivery personnel applications.
The client application allows users to upload prescriptions and update them about concerning their deliveries, which are automatically managed by the system. It also shows them the current location of the personnel that is delivering the medicine.
For the delivery personnel app, it was designed to give the users notifications when a delivery is assigned to them as well as show the location of the client.
BaryaCard | Financial App
This app is a financial app that aims to help Filipinos save money when buying from convenience stores, food stands, etc. Instead of getting the coin change right then and there, they can choose to have it deposited into their BaryaCard account. Currently, two companies have partnered with BaryaCard so that they can offer the services within the app and be part of the profit-sharing model that my clients have envisioned.
AMPC — https://play.google.com/store/apps/details?id=com.baryacard.ampc&hl=en
Mister Donut — https://play.google.com/store/apps/details?id=com.baryacard.misterdonut&hl=en
AMPC — https://play.google.com/store/apps/details?id=com.baryacard.ampc&hl=en
Mister Donut — https://play.google.com/store/apps/details?id=com.baryacard.misterdonut&hl=en
InkMyPapers | Assignment Help
InkMyPapers is a service where students can ask for help on their essays, dissertations or presentations. I created and managed a team that will develop a multitude of apps where I developed the Android app myself.
Shawer App | eLaw App
Shawer is an eLaw application that connects lawyers with potential clients. It is an online legal services marketplace connecting consumers and lawyers across the region. Shawer app is not a law firm in of itself and doesn’t provide any legal services; it merely facilitates the connection of lawyers and clients.
Shawer users can purchase in-app currency via the Google Play and the Apple App Store and after purchase can access the available services of various lawyers and services ranging from consultations to legal representation in court.
Shawer users can purchase in-app currency via the Google Play and the Apple App Store and after purchase can access the available services of various lawyers and services ranging from consultations to legal representation in court.
DURA LEX | Social Italian and European Law Application
DURA LEX is a new kind of application that aims to bring social functions to a repository of Italian and European laws. It will also have powerful searching capabilities that enable users to search for resolutions and judgments to legal court cases. Currently, it is in development.
Appily | A Journal App with a Personality Analysis
I developed a journal app that has an automatic data synchronization with the back end, a Google Drive backup, a personality analysis, and a customized feedback logic. It was also implemented with Material Design so that it is compatible up to API 15.
Paloma Forum App
This project allows employees of an existing company to communicate and share information through a mobile app. The user can enter posts, categorize, send files, and collaborate on forum postings and edit material.
MyWapBlog.com
This is a blogging app that I made for an existing blogging platform. All the designs were made by the designer and I implemented them pixel by pixel. Aside from the features shown in the video, it also has push notifications for news, reminders, and more.
GetHabal
The app functions like Uber but caters to motorcycle drivers in the Philippines. The app shows the location, creates routes and maps, and lets users see the estimated arrival time and duration to gauge travel properly. The app allows drivers to receive bookings and track their history of travel.
Education
2009 - 2013
Bachelor's Degree in Computer Science
Technological University of the Philippines - Manila, Philippines
Skills
Libraries/APIs
Node.js, Android Support Library, Retrofit 2, RxJava, Google API, X (formerly Twitter) SDK, Facebook SDK, React, REST APIs, Stripe API, Google Maps API, jQuery, Vue
Tools
Bitbucket, SourceTree, RxAndroid, Android Jetpack, Expo, WebView, Firebase Authentication, Android Studio, Xcode, Jira, Crashlytics, Visual Studio, GitHub
Languages
TypeScript, JavaScript, Kotlin, Java, C#, HTML, CSS, SQL, HTML5, GraphQL, Swift, C#.NET
Frameworks
React Native, AngularJS, Android SDK, .NET MAUI, Angular, Next.js, Redux, .NET, Espresso, Robotium, ORMLite, Vanilla JS, Bootstrap, iOS SDK, Express.js, Spring Boot
Paradigms
Model View Presenter (MVP), Agile Software Development, UI Design, UX Design, Testing, Mobile Development, Clean Code, Object-oriented Programming (OOP), Unit Testing, Spoon Testing
Platforms
Mobile, Firebase, Android, Xamarin, Algolia, Linux, iOS, Windows, Eclipse, Azure, Visual Studio Code (VS Code), Amazon Web Services (AWS)
Storage
Firebase Realtime Database, Cloud Firestore, JSON, MySQL, Cloud Deployment, Microsoft SQL Server, PostgreSQL, Databases, Google Cloud
Other
Technical Leadership, Google Material Design, Google+ Authentication, EventBus, Full-stack, API Integration, Mobile Apps, APIs, Design, Google Play Console, Geolocation, Security, User Experience (UX), User Interface (UI), OCR, App Store, Google Play Store, Authentication, React Native Navigation, IT Project Management, IT Projects, Audio, Speech to Text, Text to Speech (TTS), Architecture, Full-stack Development, Web Applications, Biometrics, Cross-platform App Development, Crypto, Image Processing, Artificial Intelligence (AI), Machine Learning, Web Development, Progressive Web Applications (PWAs), CI/CD Pipelines, Xamarin.Forms, Software Architecture, Mobile UI, Mobile Payments, Chatbots
Collaboration That Works
How to Work with Toptal
Toptal matches you directly with global industry experts from our network in hours—not weeks or months.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
Start your risk-free talent trial
Work with your chosen talent on a trial basis for up to two weeks. Pay only if you decide to hire them.
Top talent is in high demand.
Start hiring