Petru Gabriel Lupu, Developer in Arona, Spain
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Petru Gabriel Lupu

Verified Expert  in Engineering

iOS Developer

Arona, Spain
Toptal Member Since
March 25, 2019

Petru is a developer who's spent the last 14 years in the mobile industry, publishing 100+ apps in the App Store. To any project, he brings in-depth knowledge of SDKs/libraries and iOS hardware/software, exceptional OOP skills, solid Node.js knowhow, and hands-on experience with RESTful web services in mobile apps. Besides his technical expertise, he’s also comfortable with Agile workflows, working with Git, and thrives in a team environment.


Palm Mar Studios
Sketch, Adobe Photoshop, Xcode, Objective-C, Swift, Subscription Processing...
Swift, iOS, HLS.js, HTTP Live Streaming (HLS)




Preferred Environment


The most amazing...

...thing I’ve developed was my personal calisthenics app. I’m personally a big fan of the field and I use it when I go to the park every day.

Work Experience


2012 - PRESENT
Palm Mar Studios
  • Started developing my own apps out of necessity; initially, I needed an application for my exercises in the park.
  • Aimed to build apps that make money using the guiding principle "the best app is a live app."
  • Implemented my own version of ASO (app store optimizations) on a number of apps due to a lack of resources for marketing. To offset this, I used as much as possible free stuff and what I could do myself which included promoting my apps on my own Instagram, Facebook, Pinterest, and Tumblr accounts.
  • Worked the system at Apple (which included customer support, testers, and App Store reviewers) in order to get my apps in the store as fast as possible.
  • Acted as the end-to-end creator of my apps which includes development, marketing, design, testing, delivery, and more.
Technologies: Sketch, Adobe Photoshop, Xcode, Objective-C, Swift, Subscription Processing, Model View ViewModel (MVVM), Model View Controller (MVC), JSON, Git, Model View Presenter (MVP), Location Services, GraphQL, Apple TV

iOS /Swift Developer

2022 - 2023
  • Developed a live-streaming video app for a startup.
  • Acted as the product owner of the team formed by myself and another iOS developer.
  • Added many unit tests to the app and implemented MVVM on all the screens.
Technologies: Swift, iOS, HLS.js, HTTP Live Streaming (HLS)

iOS/Swift Developer

2021 - 2022
HelloFresh - Main
  • Built an app for receiving meals at home. The app is very successful in the US, Germany, and other countries.
  • Put in charge of the payment squad, responsible for bug fixing and support.
  • Participated in many meetings with a vast team of 50-100 iOS developers.
Technologies: iOS, Swift

iOS/Swift Developer

2021 - 2021
  • Developed a library app that had thousands of books.
  • Was part of the big team that was in charge of payments.
  • Became more proficient in Jira and Bitbucket while solving issues.
Technologies: Swift, iOS, Mobile, JSON

Registration Screen Development

2020 - 2020
Golden Voice Technologies Inc.
  • Built an audio live-streaming app similar to Twitter Spaces.
  • Used dependency injection, MVVM, RxSwift, and Firebase cloud functions.
  • This was my favorite client from Toptal, and I loved working for them.
Technologies: Firebase Cloud Functions, Firebase, Dependency Injection, Model View ViewModel (MVVM), RxSwift, Swift

iOS/Swift Mobile Developer

2020 - 2020
Tari Labs LLC
  • Developed Tari—a crypto app for buying and selling cryptocurrencies.
  • Paid special attention to the design and made it pixel-perfect.
  • Developed many animations, which strengthened my skills in creating beautiful designs with animations.
Technologies: Swift, iOS, Mobile Apps, Native Mobile Apps, Mobile UX, Cryptocurrency

iOS Engineer

2019 - 2020
Tocca, Inc
  • Developed this client app that was used to enter conferences.
  • Made the entire design from code, with no storyboards or XIBS.
  • Added custom CocoaPods libraries for the 1st time.
Technologies: Swift, iOS, RealmSwift, CocoaPods, Firebase, Google Cloud, Realm, OAuth, Mobile App Development

iOS Engineer

2019 - 2019
CircleIn, Inc.
  • Helped colleges and universities reach 90% of students not served by traditional student success programs.
  • Put in charge of the iOS app. I implemented the chat and redesigned the app.
  • Participated as a member of the team formed by another iOS developer and a product owner.
Technologies: Swift, iOS, Accessibility

Senior iOS Developer

2017 - 2019
Arnia Software
  • Created the Postbank app (iPhone and iPad) for Postbank, a major bank in Germany.
  • Developed for the Postbank project automation tests for basically every property, method, and class.
  • Worked with a big team for the Postbank project with some of them based in Germany, some in Poland, some in Romania, and many others working remotely.
  • Worked in an Agile software development.
  • Developed a demo for the Lego company in an effort to gain them as clients.
  • Built and presented a demo for MO2O in an effort to gain them as clients.
Technologies: Xcode, Objective-C, Swift, Subscription Processing, HTTP Live Streaming (HLS)

Senior iOS Developer

2017 - 2019
  • Worked on more than 15 apps for MO2O's clients including Balearia, Once, Man City, Athletic Bilbao, Telefonica, and many others.
  • Successfully held all of my meetings in Spanish for one year and later smoothly transitioned to an all English environment.
  • Quickly switched between projects; some days, working on 3-4 different projects with the result that I have no problem tackling new projects.
  • Developed both the Objective-C and Swift versions of products; sometimes creating 2-3 different Xcode versions for various projects.
  • Automated the commits using Jenkins and Slack; used Slack commands for uploading to the store or to different test servers.
Technologies: Xcode, Objective-C, Swift, Subscription Processing

Senior iOS Developer

2017 - 2018
  • Developed the iOS app (iPhone and iPad) for a major German bank called Postbank.
  • Worked with a big team with members who were based all over (Germany, Poland, Romania, and more) and had to work remotely.
  • Created automation tests for basically every property, method, and class that I implemented.
  • Worked in an Agile software development.
  • Tackled different tasks all over the app due to the project's size; it was a really interesting challenge to work on decade-old lines of code.
Technologies: Xcode, Objective-C, Subscription Processing

Senior iOS Developer

2015 - 2016
Silver Credit
  • Developed Silver Credit, an iOS (iPhone, iPad) app that helps you find the best bank card for you. A user answers a few questions and based on the information collected, a selection of cards are suggested. You can also apply for cards through the app.
  • Successfully worked with a very demanding product owner.
  • Built up the back-end in Parse initially and then migrated it to Firebase.
  • Helped on the project with some cloud functions written in Node.js.
  • Rewrote the whole app from Objective-C to Swift.
Technologies: Xcode, Objective-C, Swift

Senior iOS Developer

2015 - 2016
Irresistible Me
  • Built an online shop app that sold hair extensions to women from scratch with a small team consisting of a designer, a QA, a back-end developer, a PM, and an iOS developer.
  • Created various promotions often and quickly as we had to change them quite often.
  • Collaborated closely with the Adore Me team, the main competitor of Victoria's Secret in order to learn more about the industry; they helped a great deal by sharing their knowledge about online magazines.
  • Locally stored a major part of the data so the users could have access to the data really fast.
  • Implemented API calls in the background and compared the information saved locally with the information received from the server. If nothing changed, i did not do anything. If something was different, I updated the local data and refreshed the page for the user.
Technologies: Xcode, Objective-C, Swift, iOS API

Co-founder | iOS Developer

2013 - 2016
Zumzet Mobile
  • Created a number of personal apps that covered a large range of categories with a friend of mine (iOS, Android, and macOS).
  • Automated a lot of builds and changes with Fastlane.
Technologies: Xcode, Swift, Objective-C

Senior iOS Developer

2014 - 2015
Sell It
  • Developed the iPhone and iPad version of Sell it. The company invested over 2-3 million dollars in advertising in New York in the subway and TV. The company was pretty successful and was sold to Wallapop for a lot of money and actions.
  • Worked very closely with Fabrice Grinda, one of the greatest entrepreneurs in France. He was named by Forbes the top entrepreneur in the world.
  • Worked with a large team that had members based all over different parts of the world.
Technologies: Objective-C, iOS, Xcode

Senior iOS Developer

2013 - 2015
  • Developed the iPhone and iPad version of Lofty, a marketplace for antiquities.
  • Created the iPhone version of Lofty Game.
  • Worked with one of the biggest entrepreneurs in the world, Fabrice Grinda.
  • Began my foray into working remotely.
Technologies: Xcode, iOS, Objective-C

iOS Developer

2012 - 2013
Mobile Fun
  • Developed HOM (High on Music), an online social networking service. Users must register before using the site after which they may create a personal profile, add other users as friends, exchange messages, and receive automatic notifications when they update their profile. It's like Facebook for music.
  • Worked within a small company and really enjoyed our time together.
  • Attended numerous meetings with the founder of the company resulting in that many of our ideas were implemented in the app.
Technologies: Objective-C, Xcode, iOS

J2EE Developer

2011 - 2012
Info World
  • Worked on the EUGEN Suite which is designed to improve the quality and management of clinical and hospital care in the areas of clinical process analysis and activity-based costing.
  • Fixed bugs, reviewed code, and investigated errors using Eclipse/Visual Studio.
  • Parsed XML using JAXB.
  • Worked with JBoss, Fiddler, and Far Manager.
  • Deployed websites on different servers.
Technologies: Java, .NET, XML, SQL, C#

Team Lead Programmer

2005 - 2011
Advanced Mobile Applications
  • Led the US sprint team which consisted of over 12 people.
  • Organized team resources in order to deliver all the projects in time using Microsoft Project.
  • Traveled to New York, Miami, and Kansas City (United States) in order to attend different conferences regarding mobile technology.
  • Worked in New York office for more than a year.
  • Worked for a company that grew from 20 people to 200 people in less than a year.
  • Developed with Brew and Visual Studio initially before moving onto Java ME and Objective-C.
Technologies: Objective-C, iOS, BREW, Java ME

Tocca (via Toptal)

This app allows you to easily synchronize and manage all your business contacts in a secure and private way. Now you can use your phone to do the following:
• Share your contact information with a swipe of your phone and connect with the people in real-time. Simply scan the contact information via business card, vCard, or your Tocca ID and instantly your information has been passed along.
• Connect with contacts in your trusted extended family that are relevant to you and your needs. This feature helps you build relationships in authentic ways and truly grow your network.

CircleIn (via Toptal)

This project was one of my first Toptal clients and we developed the app to help students. We used Swift 4.2 and then 5.0 to develop it using the MVVM pattern. I worked with Twilio for video communication and messages.

Project Features:
• Integration with Firebase
• Push notifications were implemented with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics


JennAir is the deluxe division of Whirlpool and we developed it using Rx Swift.

I developed the framework that all the Whirlpool companies will use and first tried it out on JennAir.

Project Features:
• Integration with Firebase
• Push notifications were done with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Jack and Ferdi Bleisure Travel

Jack and Ferdi is your key to unlock memorable business trips. It was created by a collective of travelers who wanted to take away more than a fridge magnet.

I used Swift 5.0 to develop this app using the MVVM pattern.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Stretching and Flexibility Plans

This is my most successful app in the App Store. It has over 100 customizable stretching exercises, over 50 predefined workout routines, and over 50 healthy recipes for meals.

I created everything from scratch from taking photos to developing the whole app initially in Objective-C then in Swift.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Plank | 30-day Challenge

Plank is a fitness app that was developed using Swift 5.0.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Calisthenics Workout
This is one of my most successful apps; I initially built it with Objective-C then Swift 5.0. It also has an Apple watch app version.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Baby Sleep and Sounds
I developed this app with Swift 4.2.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

James Cookbook
I developed this healthy meals app with Swift 5.0.

Postbank Finanzassistent

I developed with Objective-C this Postbank mobile companion for your bank account. We also conducted unit testing for any class, method, or property we added, so I am very experienced with unit and E2E testing.

BALEÀRIA: Reserva tu viaje

Buy and reserve tickets for boats on BALEÀRIA.

Jean Louis David Addict

This app connects you to beauty salons where you can buy products and make reservations.

Juegos ONCE

Juegos ONCE is an app that connects you to the national lottery in Spain. It's their companion app where you can see the numbers and more.

Front Office Football
I developed this football manager game using Swift 5.0; basically it's a text-based game.

Project Features:
• Integration with Firebase
• Push notifications with OneSignal and Firebase
• Deep and dynamic links with
• Analytics with Google Analytics

Photo Video Editor 4 Live Camera | Selfie Effects
I developed this app with Swift 4.2.
2000 - 2005

Master's Degree in Computer Science, Information Technology, and Automated Systems Science

The Faculty of Automatic Control and Computers | Automatica si Calculatoare - Bucharest, Romania

1996 - 2000

Bachelor of Science Degree in Computer Programming

Tudor Vianu National High School of Computer Science | Colegiul National de Informatica Tudor Vianu - Bucharest, Romania


iOS API, CocoaPods, HLS.js, Python API, Node.js, Facebook SDK, RxSwift, REST APIs, ReactiveX


Xcode, Xcode Playgrounds, WebStorm, Sketch, GitHub, Bitbucket, GitLab, Jira, Redmine, Zeplin, Stash, Sympli, Git, Google Analytics,, Adobe Photoshop


iOS SDK, UIKit, .NET, RealmSwift, Flutter


Swift 4, Swift 3, Swift 2, Swift 1, Swift, Objective-C, PHP, Python, Python 3, Python 2, GraphQL, C#, SQL, XML, Java


Model View Controller (MVC), RESTful Development, Dependency Injection, Model View ViewModel (MVVM), Model View Presenter (MVP)


iOS, iOS 12, iOS 11, iOS 10+, Magento, Firebase, Mobile, Apple TV, Java ME, BREW


JSON, Google Cloud, Realm


Development, iOS TV, iOS Video, Carthage, Embedded Software, Firebase Cloud Functions, Mobile App Development, Subscription Processing, Location Services, HTTP Live Streaming (HLS), Mobile Apps, Native Mobile Apps, Near-field Communication (NFC), Payment Gateways, Photoshop CC 2019, Video Chat, Architecture, Accessibility, OAuth, Mobile UX, Cryptocurrency

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