Sarah Ahmed, Developer in Karachi, Sindh, Pakistan
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Sarah Ahmed

Verified Expert  in Engineering

Full-stack Developer

Karachi, Sindh, Pakistan
Toptal Member Since
March 2, 2022

Sarah is a senior full-stack engineer who has developed web and mobile applications for clients while working remotely for close to seven years. She specializes in JavaScript and React, React Native, and Node.js frameworks; AWS serverless back ends; and test-driven development for algorithmic work. Along with her passion for software development, Sarah loves to mentor and has published many educational videos on YouTube. In her free time, she enjoys finding UI inspiration on Dribbble.


FieldStream AB
React, Tailwind CSS, Charts, GraphQL, Web Dashboards, Firebase, State Machines...
EcoEnergy Pakistan
React, React Native, Amazon Web Services (AWS), Full-stack Development, Jest...
Mentorship & Coaching, JavaScript, Web Development, Content, Edtech Design...




Preferred Environment

MacOS, Visual Studio Code (VS Code), Slack, Jira, Email, Git, TypeScript, ECMAScript (ES6)

The most amazing...

...thing I've done was the test-driven implementation of a solar sizing algorithm. It takes in a customer's electricity needs and suggests a solar PV solution.

Work Experience

Senior Front-end Developer

2022 - 2022
FieldStream AB
  • Architected the dashboard web app, determined the tech stack best suited for it, and implemented its design with pixel-perfect precision.
  • Impressed the client with fast delivery and flawless implementation.
  • Developed the React app from the ground up, following best coding practices.
Technologies: React, Tailwind CSS, Charts, GraphQL, Web Dashboards, Firebase, State Machines, TypeScript, GitHub, Full-stack, Social Media Apps, REST APIs, Web Applications, Chakra UI, APIs, Responsive UI, Pixel Perfect, Agile, Zapier, Chart.js, Minimum Viable Product (MVP), ECMAScript (ES6), Architecture, Software Design, Startups, Graphs

Senior Software Engineer

2019 - 2022
EcoEnergy Pakistan
  • Led the development of an intelligent system to automate solar PV system sizing.
  • Developed a mobile and web front end for the sizing algorithm.
  • Self-learned solar sizing concepts and domain knowledge, which allowed me to collaborate more effectively with solar experts and convert their logic into code.
  • Created training videos to help the company's village staff leverage technology in sales.
Technologies: React, React Native, Amazon Web Services (AWS), Full-stack Development, Jest, Automated Testing, Jira, Scrum, JavaScript, Python, Git, TypeScript, Web & Mobile Applications, Front-end Development, Front-end, JSX, AWS CloudFormation, AWS Lambda, Amazon S3 (AWS S3), CI/CD Pipelines, Express.js, Android, iOS, Mobile, Quality Control (QC), Quality Assurance (QA), Material UI, Charts, MobX, User Interface (UI), User Experience (UX), Design, Performance, Redux, Gatsby, Geolocation, Mapping, MongoDB, GitHub, Amazon DynamoDB, Full-stack, Expo, Mobile Development, Node.js, REST APIs, Web Applications, PostCSS, UX Design, APIs, Testing, AWS AppSync, AWS Amplify, Integration Testing, Responsive UI, Pixel Perfect, Mobile Apps, Amazon Cognito, AWS IAM, Agile, Chart.js, Minimum Viable Product (MVP), Design Systems, Mobile App Design, Mobile Design, SaaS, ECMAScript (ES6), Cloud, Architecture, App Development, Cross-platform App Development, Cross-platform, Software Design, Startups, Apache Velocity, Graphic Design, Web Design, DevOps

Lead Instructor

2018 - 2019
  • Mentored two batches of 100 students each—mostly underprivileged women—helping them learn web development and find jobs in tech.
  • Created more than 100 video lectures and published them on YouTube to maximize learning. Students were of diverse backgrounds and ages, and these videos helped them learn at their own pace.
  • Enabled women to support their families financially; many of my students work at reputable local software houses and earn competitive salaries.
  • Received the Best Mentor award from the funding partners based on exceptionally positive feedback from students.
Technologies: Mentorship & Coaching, JavaScript, Web Development, Edtech Design, Videos, Content, Axios, React, HTML, CSS, JSX, Material UI, TypeScript, GitHub, Full-stack, Mobile Development, REST APIs, Web Applications, SQL, APIs, Testing, XML, Responsive UI, Pixel Perfect, Mobile Apps, Bootstrap, Chart.js, Design Systems, Mobile App Design, Mobile Design, Code Review, Team Leadership, ECMAScript (ES6), Leadership

Hybrid Mobile App and MEAN Developer

2015 - 2018
Online Freelance Agency
  • Remotely developed hybrid mobile applications for clients from the United Kingdom, United States, and France and published those apps on Google Play and the App Store.
  • Received five-star reviews on all jobs with great reviews and appreciation from clients, a Top-rated badge, and a 100% Job Success badge.
  • Converted all my clients into repeat clients by delivering quality apps on time.
Technologies: MEAN Stack, Angular, Ionic, Android, iOS, JavaScript, Node.js, InVision App, Web & Mobile Applications, Mobile App Development, Web Development, Front-end, Mobile, MySQL, SQLite, Quality Assurance (QA), Quality Control (QC), User Experience (UX), Firebase, Material UI, Charts, Geolocation, Mapping, Firebase Cloud Functions, GitHub, Amazon Web Services (AWS), Full-stack, Mobile Development, REST APIs, Web Applications, SQL, APIs, Calendars, XML, Responsive UI, Pixel Perfect, Mobile Apps, Chart.js, ECMAScript (ES6), App Development, Cross-platform App Development, Cross-platform, Software Design, Startups, Graphic Design, Web Design

Software Developer

2017 - 2017
Recurship (Acquired by
  • Developed hybrid iOS and Android mobile and web applications for Backtable, one of the company's clients.
  • Performed well above expectations as a junior developer by single-handedly developing an application stack for BackTable.
  • Received amazing feedback from the CTO during my farewell one-on-one session with him. He said, "You are one in a million. Our doors will always be open for you."
  • Conducted development sessions for my Recurship colleagues, spoke at technical meetups, and participated in mentorship opportunities.
Technologies: JavaScript, Angular, MEAN Stack, Ionic, Unit Testing, Web & Mobile Applications, Mobile App Development, Web Development, Mentorship & Coaching, iOS, Android, Front-end, Mobile, Progressive Web Applications (PWA), Firebase, GitHub, Full-stack, eCommerce, Social Media Apps, Mobile Development, REST APIs, Web Applications, APIs, Testing, Responsive UI, Pixel Perfect, Mobile Apps, Agile, Bootstrap, ECMAScript (ES6), App Development, Cross-platform App Development, Cross-platform

Samsa Mobile and Web Application
A web application for sizing a solar PV solution based on the customer’s energy requirements. Users can enter their daily electricity needs and duration of use on the front end, such as fans, air conditioners, and lights. Then the application suggests a solar PV solution, including the panel array, battery bank, inverter size, wiring, and other electrical components required for installation. As the full-stack developer, I built the front end, serverless back end, automated unit testing, and UI design.

• React Native mobile and React web front end
• Test-driven sizing algorithm development using Jest and JavaScript
• Serverless back end using AWS Cognito, AppSync API, Lambda, DynamoDB, SES, S3, CloudFormation, CloudWatch, and more
• UI design using InVision App

A sports betting tips and predictions app for gamblers, featuring many stats and live soccer scores to help with betting.

• Ionic (Angular) front end
• In-app purchases
• Published to Google Play and the App Store

Rapid Notifier
A mobile notifier app for the NED University of Engineering and Technology allows university administrators to broadcast notifications to teachers and students. These notifications can include text, images, files, lists, links, and more. As the full-stack developer, I delivered the front end, REST API, unit testing, and UI design.

• Ionic (Angular) front end
• Push notifications
• Node.js REST API
• MongoDB database
• Published to Google Play and the App Store
• UI design using InVision App

Hospital for Special Surgery App
The official mobile app for Hospital for Special Surgery (HSS) in New York City.

Functionality for Patients
• Maintain your complete medical record and test results in one place.
• Message doctors and manage your appointment calendar.
• Get instant notifications for time-sensitive updates about your care.
• Schedule in-person or virtual appointments with physicians, physical therapists, and other specialists.
• Learn about care at HSS, the conditions it treats, locations, and more.
• Explore expert tips for healthy living, read patient stories, and register for online events.
• Make appointments and access information even without an account.

• Ionic (Angular) front end
• Published to Google Play and the App Store

Lupus Minder
A mobile app for lupus patients developed for Hospital for Special Surgery (HSS) in New York City.

Functionality for Patients
• Track and share your symptoms: record your symptoms between physician visits with notes and photos and share these trends with your doctor.
• Manage your medications: set reminders and record side effects.
• Be ready for your doctor visits: get appointment reminders, write down questions you want to ask your doctor, and note what your doctor tells you.
• Be informed about lupus research, initiatives, and support programs.

• Ionic (Angular) front end
• Published to Google Play and the App Store

ACCME2018 App

I was responsible for performing detailed quality assurance on this app - list down all the glitches, any missing validations, UX analysis, etc.

The required output was to create a thorough document with all my findings, along with reproducible steps for each result.

ColourLess - A Memory Game
A Unity3D game that challenges your memory to remember colors - like a "Guess Who Card" game.

This was the first app I published on the Android store Google Play back in 2015. I was interested in how games are developed and decided to design and develop a simple game using Unity3D and publish it to Google Play.

Seamless Communication for Hearing Impaired
This is a sign-language-to-voice (and vice-versa) translator, developed in Unity3D using Kinect.

It consists of two modules:

1. Dictionary module: A mobile application that converts text/voice into sign language (text-to-sign dictionary). A rigged 3D model performs the conversion. We created a database of 30 3D-rigged gestures, including 78-word variations. The application can take a sentence as input and understand synonyms; then, the 3D model performs the corresponding gestures flawlessly. The sole purpose behind developing this app is to replace a human translator with an automated one.

2. Distant communication module: This module attempts to replicate the existing phone call system for hearing impaired people who use sign language instead of voice as their mode of communication. This module takes gesture input using a Kinect device to send the gesture to a gesture recognizer, translating it into text. This text is then sent over a Wi-Fi connection to a recipient device. If the recipient is also hearing impaired, the received text is sent to a gesture synthesizer that outputs a series of gestures played back by a 3D rigged model.

Book Panda
It is based on a hypothetical book shop called Book Panda, where you can purchase books online after reading reviews by other customers.

Please visit the Book-Panda website here(

FieldStream Drag and Drop Dashboard with Charts
Fieldstream AB is a Marketing analysis firm. I developed a drag-and-drop dashboard for their front-end app that heavily used charts. Figma designs were provided.

• Dashboard with a draggable layout.
• Data visualization via charts.
• Authentication (Sign In, Reset Password) using Firebase.
• Pixel-perfect implementation of provided Figma designs.
• Best coding practices.
• Automated unit tests for algorithmic work.

Drrops Mobile App

Drrops is an artist-owned platform connecting creators with their fans at live events. Check in using your location or a QR code at the show to gain access to hidden digital communities. Once you're in, you can chat with the artist, check out exclusive backstage content, collect free tracks and videos, and more! consulted me, Pakistan's leading online travel agency, for Stripe integration in their official website using Stripe API without using Stripe UI elements. The website is built on React and has a server written in Python.

BackTable Web and Mobile App
I created a web and mobile application for BackTable, a community-driven, in-depth knowledge base for all things interventional radiology, covering tools, techniques, and expert guidance on more than 30 interventional radiology procedures.

Here is a list of features that I implemented:
• Create a catalog of devices.
• Add a new device.
• Rate or review a device.
• Post a question about a device.
• See what ratings or reviews a device has received from other physicians.
• Invite people to BackTable.
• Edit a physician profile.
• View a physician profile and their activity (devices, reviews, and questions) on BackTable.
• Login and signup.

Drrops for Human Collective

Drrops is an artist-owned platform connecting creators with their fans at live events.

Here is a list of features that I worked on:
• The new "Happening Now" feature will reduce the check-in to just a few seconds.
• The "Universal Link" check-in workflow will allow fans to check in with a QR code.
• The "Performance Mode" cloud setting allows us to deploy more resources for major shows/tours and reduce load times.
• Many UI and performance tweaks like the passes tab, account deletion, optimizing video playback in the collection, and more.


React, Node.js, MobX, REST APIs, Chart.js, Stripe API, AWS Amplify, React Router, JavaScript Charting, Formik, React Hook Form, Stripe, Three.js


GitHub, Expo, AWS AppSync, Amazon Cognito, MongoDB Atlas, Figma, WebView, AWS IAM, Zapier, Skype, Jira, Git, Slack, JSX, AWS CloudFormation, Google Docs, Photoshop 7, Blender, React Apollo, Firebase Test Lab, PostCSS


React Native, Express.js, Material UI, Next.js, Tailwind CSS, Bootstrap, Ionic, Jest, Redux, .NET, Django, Angular, PhoneGap, Unity3D, Microsoft Kinect, Loopback, Apache Velocity


JavaScript, TypeScript, HTML, CSS, SQL, XML, ECMAScript (ES6), GraphQL, C#, Python, C#.NET, Java, Sass, HTML5


Automated Testing, Unit Testing, Mobile Development, Responsive Web Design (RWD), Testing, App Development, Cross-platform, REST, UI Design, UX Design, Agile, Mobile App Design, Mobile Design, DevOps, MEAN Stack, Role-based Access Control (RBAC), Scrum, Desktop App Development, Test-driven Development (TDD)


Amazon Web Services (AWS), Android, iOS, Mobile, Firebase, AWS Lambda, MacOS, Eclipse, Visual Studio Code (VS Code)


MongoDB, MySQL, Amazon DynamoDB, Amazon S3 (AWS S3), SQLite

Industry Expertise

Social Media, Web Design


MERN Stack, Property-based Testing, Full-stack Development, Web Development, Mobile App Development, Web & Mobile Applications, Front-end, Axios, Quality Assurance (QA), Quality Control (QC), Charts, Dashboards, Geolocation, Full-stack, API Integration, Web Applications, APIs, Calendars, Integration Testing, Responsive UI, Pixel Perfect, Mobile Apps, Minimum Viable Product (MVP), Code Review, Single-page Applications (SPA), Cross-platform App Development, Startups, Graphs, Back-end, Publishing, Android Game Development, Performance, User Experience (UX), Design, User Interface (UI), Data Visualization, Mapping, Firebase Cloud Functions, eCommerce, Social Media Apps, Chakra UI, SaaS, Team Leadership, Health, Cloud, Architecture, Leadership, Software Design, InVision App, Mobile App UI, In-app Purchases, Cordova, Push Notifications, Freelancing, Mentorship & Coaching, Content, Email, Front-end Development, Back-end Development, Serverless, CI/CD Pipelines, Analysis, UX Analysis, Progressive Web Applications (PWA), Game Development, Graphics, Sprites, Gatsby, Internationalization, Charting, State Machines, XState, Wizards, Tables, Web Dashboards, Design Systems, Edtech Design, Videos, Graphic Design

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