Samuel Edwin

An app that uses AI to help users learn conversational Spanish lets users practice their conversational Spanish using text or audio messages.

The app's fun feature is the audio conversation, in which the user can freely speak to the AI in hands-free mode. The user does not have to stare at the phone in this mode. They can plug in their earphones, walk in the park, and improve their Spanish skills.

I built every feature in the iOS app. Judging by the design and requirements, I concluded that SwiftUI and composable architecture are the best choices for this project. With SwiftUI, I can quickly build the UI and save development time. With composable architecture, complex audio recording interactions can be greatly simplified and unit-tested to ensure smooth conversations.

A React Native chat app that is used by the client's internal community with 5,000 users.

The project was way behind schedule because the client didn't have a React Native expert.

I solved 90% of the bugs in two weeks and developed the rest of the features to completion.

The app was launched with a 99% crash-free rate.

Migrated the Indonesian Government's eCommerce platform from an older, insecure web version to use the latest technology. This increased time-to-first-byte performance by 200%.

I also led all technical aspects of front-end applications, including development, testing, and deployment. I performed code reviews and gave feedback to pull requests, which increased developer productivity by 20%.

I hired and interviewed software engineer candidates and worked with back-end developers to develop a GraphQL schema that is easy for developers to use. Additionally, I built a CI/CD environment and deployed the application in just five minutes. Finally, I built and documented best practices for front-end developers in the team.

A CRM application was developed to help medical science liaisons perform daily operations.

The application currently serves 500 daily active users and saves 20 monthly hours per user by automating mundane tasks.

The application helps medical science liaisons by:
• Logging their research notes.
• Generating PDFs based on complex filters such as medicine names.
• Displaying a dashboard of current tasks and progress.
• Doing AI analysis of their research notes and calculating sentimental analysis.

I acted as the CTO, building the application with two other developers.

I also acted as the product manager, figuring out the features needed to be built by talking with the CEO and customers.

I led this project on the technical side, which involved improving the UI and UX of Tokopedia's existing home screen.

You can see the complexity of the feature in the video:
• Lots of different widgets are displayed on one screen.
• A sticky tab bar (0:11 in the video) that needed special care to implement.
• Pinterest-like layout at the bottom of the list.
• Needs to be smooth on iPhone 5, the oldest iPhone we support.

This was almost impossible to implement, especially the sticky tab bar. Nobody knew how to implement this at that time. I managed to find an elegant implementation by reverse engineering Instagram, which used the same UI pattern.

The previous iteration had many widgets, and the code was a mess to maintain. This iteration has many more widgets, but I managed to find a code structure that makes these widgets easy to maintain. Maintaining this feature is fun now, unlike before.

To make it smooth on iPhone 5, I learned new tricks from the iOS community to optimize UI performance. Scrolling on iPhone 5 now feels butter smooth. I achieved the Pinterest-like layout by applying my extensive knowledge of the iOS UI system.

Tokopedia has lots of UI designers working on multiple products. They don't frequently communicate, resulting in inconsistent UI behavior. This is a huge waste of time because engineers must repeatedly build the same UI components.

The engineering team and the UI design team solved this problem by creating a reusable component library.

Here are my contributions to this project:
• Talking to UI designers whenever something was impossible to implement and offering alternative solutions that work just as well.
• Brainstorming with engineers on how to implement tricky components.
• Building some of the UI components.
• Reviewing the components' API to make them easy to use.

This resulted in a huge productivity boost both for the engineers and the UI designers. Engineers didn't have to waste time rebuilding the same components anymore, and UI designers didn't have to reinvent new ones. They can now simply pick a UI element from the catalog and plug it into Figma.

I led this rewrite project with one team member. This rewrite was necessary because of a few reasons:
• Thousands of lines in one file, very hard to understand.
• Crashes frequently.
• Lots of bugs.
• Slow performance.

Here's what I did to solve these problems:
• Developed a coding pattern that makes it easy to maintain a large number of different widgets.
• Used Swift's language features to make crashes almost impossible to happen.
• Reduced the amount of code written significantly by adopting a framework called IGListKit.
• Adopted a new UI framework to make the performance smooth.

The Tokopedia app contains dozens of different products. The app supports eCommerce activities, paying monthly bills, booking flights, social commerce, and much more. This means the codebase is huge, which takes a lot of time to build. It can take 30 minutes to build a project, wasting a lot of engineers' time.

I led this project along with two engineers with one main goal—to improve the engineers' productivity by improving build speed.

I did two things here; the first one is splitting the code into multiple modules, ensuring that rebuilds only happen for the code that we change. To make this happen, I learned the inner workings of the Xcode build system to learn why rebuilds happen. The second one is adopting Bazel as our build system. Using Bazel's cache, we can shave off more time to build our app. We now only need to spend around two minutes for our app to build successfully.

At Tokopedia, we use a lot of back-end services in the app. It is often hard to know when something went wrong with the back-end side.

I contributed to this project by talking to engineers and their managers to define such problems. I prioritized solving the issues in the order of their occurrence rate.

Here are some issues we often encounter:
• Images often don't load under specific internet providers.
• Some features suddenly don't work because of a back-end deployment that went wrong.
• Wrong deep link URLs stop the users from navigating to a particular screen.

We then used New Relic to log all the problems described above. We built dashboards and alerts to be notified immediately when something went wrong, so the troubleshooting time goes way faster. This makes our engineers feel safe because whatever problems that show up, they have the tools to solve them.

A tvOS app that provides entertainment through streaming TV shows similar to Netflix.
I translate the design from Figma into a usable app used by end-users.

One particularly challenging part of the project is managing the focus for remote controls, which I learned a lot from this project.

Technologies used:
• SwiftUI
• Combine
• Composable Architecture (Redux)

This is a feature that lets users book Uber from the Tokopedia app.

We use React Native on iOS for this feature to speed up development time.

This feature handles the same edge cases as the original Uber app, with Redux as the state management tool.

Using React Native, iOS development is 50% faster than that of the Android platform that uses native code.

An effort to create a TypeScript infrastructure library that is used by the iOS and Android team.

The library covers the most common use cases that product engineers need:

• Networking
• Authentication
• Navigation
• Deeplinking
• Push notification

The most important thing in this project was the API design. The APIs we designed had to work on iOS and Android and be easy for product engineers to use.

A Next.js app that I built to demonstrate my skill in building a full-stack React app. It has several functionalities: create/edit a new shop, add/edit products, and manage catalogs for the shop.

To get the best performance, every page is rendered with server-side rendering to reduce API request delays. The security aspect was also taken care of. Only the shop's owner can edit the shop's information and products. AI generates the shop's names, descriptions, and images entirely.

A custom website redesign for FCamara UK.

My main task was to build the website pages using designs in Figma as a reference.

The website was built using Next.js and Tailwind CSS. It also has a Cloudflare CAPTCHA on the contact page to prevent bots from filling out the contact form, which reduces the spam rate by 95%. This website has responsive designs accommodated for phones, iPads, and laptop screens. I improvised the iPad design by finding inspiration online and applying what I learned to build the layout.

The designer didn't have the design for the tablet layout.

The website is hosted in Azure. I built it using GitHub Actions and uploaded the build to Azure.

A set of reusable React components based on this Figma (Figma.com/community/file/1405573618937136138/gumroad-design-system-community-beta).

Implemented with React, Tailwind CSS, TypeScript, and StoryBook.

The components implemented are:
• Alert
• Button
• Checkbox
• LikeButton
• Modal
• Pill
• Radio
• Toggle
• Tooltip

A responsive website implemented with Next.js, React and TailwindCSS.

This is a website that clones some of the pages from gumroad.com

The goal of this project is to showcase my responsive web development capabilities.

This website supports mobile, tablet and desktop layouts.

Dark mode is also supported in this website.

A nearly production ready GraphQL server incorporating industry best practices. Written in TypeScript, Apollo GraphQL and SQLite.

✅ Well designed schema with reusable objects.
✅ Standard authorization: Users can only modify products for their own shop, etc.
✅ Field level authorization: Only admins and shop owners can see the shop's address, Only admins and the user can see the user's date of birth.
✅ Malicious query protection: Queries beyond certain depth are rejected.
✅ Data loader pattern to prevent n+1 query problem.
✅ Relay compliant pagination.
✅ Input limit validation.
✅ Robust error handling.
✅ 100% type safety with TypeScript and graphql-codegen.