Grayson is available for hire

Grayson Ho

Verified Expert in Engineering

iOS Developer

Location

New York, NY, United States

Toptal Member Since

September 7, 2022

Grayson is a senior iOS engineer experienced in building mobile products with millions of daily active users and consumer products that scale fast. He has worked as a senior mobile developer at well-known companies, contributing to a finance super app at Revolut, a crypto wallet and exchange for Blockchain.com, and a top downloaded note-taking app at GoodNotes. Grayson understands the whole product development process, handling features from design to public launch.

Front-end MacOS Xcode iOS Mobile Model View Viewmodel (MVVM)Swift Swift 2 Swift 3 Agile Project Management Project Management iOS SDK Mobile Development UIKit GitHub

Portfolio

Revolut

Swift 5, Xcode, iOS, MacOS, Mobile, RxSwift, SwiftUI, Combine, Mobile Apps...

Wombat Exchange

Solidity, TypeScript, React, Node.js, Agile Project Management...

Blockchain

Swift 5, iOS, Xcode, MacOS, Mobile, RxSwift, SwiftUI, Combine, Mobile Apps...

Experience

Xcode - 5 years Model View Viewmodel (MVVM) - 5 years Native Mobile Apps - 5 years iOS - 5 years Swift 5 - 5 years RxSwift - 3 years SwiftUI - 2 years Combine - 2 years

Availability

Full-time

Preferred Environment

MacOS, Xcode, Swift 5, iOS, TypeScript, JavaScript, Front-end

The most amazing...

...products I've built are a finance app for Revolut and an educational note-taking app for GoodNotes, constantly ranked as number one in the App Store.

Work Experience

Senior iOS Engineer

2022 - PRESENT

Revolut

Led an 8-person team to develop a joint accounts feature for the Revolut Retail app, enabling users to spend on a shared digital wallet.
Fixed miscellaneous bugs and made minor improvements to the payment transactions feature, resulting in a 99% crash‑free rate for 19 million weekly active users.
Improved the developer experience by shipping new components and updates in the design system.

Technologies: Swift 5, Xcode, iOS, MacOS, Mobile, RxSwift, SwiftUI, Combine, Mobile Apps, Swift, Android, Native Mobile Apps, Swift 2, Swift 3, Agile Project Management, Product Management, Project Management, Firebase, Test-driven Development (TDD), Atlassian, Jira, iOS SDK, Objective-C, HTML, Front-end, Figma, Flutter, Mobile Development, Full-stack, Model View Viewmodel (MVVM), Project Planning, Requirements Analysis, Product Strategy, UIKit, GitHub, Animation, A/B Testing, Automated Testing, CI/CD Pipelines, Google Cloud Platform (GCP), APIs, Team Leadership, Architecture, Video Chat, React Native, Wireless Protocols, Wireless, Core Data, CircleCI, TestFlight, Docker, Kotlin, Software Architecture, Microservices, eCommerce, Technical Leadership, Startups, Scalability, Planning, Finance, Agile, DevOps, Amazon Web Services (AWS), Azure, App Store, Subscriptions, User Interface (UI), User Experience (UX), Widgets, UI Animation, CallKit, Cocoa Touch, REST APIs, WebSockets, Video Streaming, Moya, Codable, Web Development, AVFoundation, Core Image, Virtual Reality (VR), Non-fungible Tokens (NFT), Cloud Firestore

Senior dApp Engineer

2021 - PRESENT

Wombat Exchange

Built decentralized applications (DApps) using TypeScript with React and Solidity for smart contracts.
Created an analytics dashboard using GraphQL and React to show transaction volumes and summaries.
Handled a protocol with over USD$20 million of total value locked and a record of USD$60 million in daily volume transactions.

Technologies: Solidity, TypeScript, React, Node.js, Agile Project Management, Product Management, Project Management, Firebase, Test-driven Development (TDD), MongoDB, Atlassian, Jira, CSS, JavaScript, HTML, Front-end, Prisma, Next.js, Figma, Mobile Development, Full-stack, Project Planning, Requirements Analysis, Product Strategy, GitHub, Animation, A/B Testing, Automated Testing, CI/CD Pipelines, APIs, Team Leadership, Architecture, React Native, CircleCI, TestFlight, Docker, Software Architecture, Microservices, eCommerce, Technical Leadership, Startups, Scalability, Planning, Finance, Agile, DevOps, Amazon Web Services (AWS), Azure, App Store, Subscriptions, User Interface (UI), User Experience (UX), Widgets, UI Animation, CallKit, Cocoa Touch, REST APIs, Moya, Codable, Web Development, Redux, AVFoundation, Core Image, Virtual Reality (VR), Non-fungible Tokens (NFT), Cloud Firestore

iOS Engineer

2021 - 2022

Blockchain

Led and shipped the new single sign-on feature for the iOS mobile application using SwiftUI, Combine, and the Composable Architecture pattern. It resulted in 41% more sign‑ups and 37% fewer customer support requests.
Modularized various crypto transaction features with a Clean Architecture pattern that reduces the CI build time by 24%.
Implemented a design system to improve the developer experience, achieving an internal NPS of 4.2 out of 5.

Technologies: Swift 5, iOS, Xcode, MacOS, Mobile, RxSwift, SwiftUI, Combine, Mobile Apps, Swift, Android, Native Mobile Apps, Swift 2, Swift 3, Agile Project Management, Product Management, Project Management, Firebase, Test-driven Development (TDD), MongoDB, Atlassian, Jira, iOS SDK, Objective-C, HTML, Figma, Amazon RDS, Mobile Development, Full-stack, Model View Viewmodel (MVVM), Project Planning, Requirements Analysis, Product Strategy, UIKit, GitHub, Animation, A/B Testing, Automated Testing, CI/CD Pipelines, Google Cloud Platform (GCP), APIs, Architecture, Wireless Protocols, CircleCI, TestFlight, Docker, Kotlin, Software Architecture, Microservices, Technical Leadership, Startups, Scalability, Planning, Finance, Agile, DevOps, Amazon Web Services (AWS), Azure, React Native, App Store, Subscriptions, User Interface (UI), User Experience (UX), UI Animation, REST APIs, Codable, Image Manipulation, AVFoundation, Core Image, Non-fungible Tokens (NFT)

iOS Engineer

2020 - 2021

GoodNotes

Led and shipped a notes-sharing platform on iOS to 10 million monthly active users of GoodNotes 5. Worked with RxSwift, CQRS pattern, and conflict‑free replicated data types.
Set up CI/CD pipelines for app deployments using Fastlane and Circle CI.
Introduced a release cadence framework that boosted team‑wise productivity.

Technologies: Swift 5, Xcode, iOS, MacOS, Mobile, RxSwift, SwiftUI, Combine, Mobile Apps, Swift, Native Mobile Apps, Swift 2, Swift 3, Agile Project Management, Product Management, Project Management, Firebase, Test-driven Development (TDD), MongoDB, Atlassian, Jira, iOS SDK, Objective-C, HTML, Figma, Amazon RDS, Mobile Development, Full-stack, Model View Viewmodel (MVVM), Project Planning, Requirements Analysis, Product Strategy, UIKit, GitHub, Animation, A/B Testing, Automated Testing, CI/CD Pipelines, APIs, WebRTC, Architecture, Wireless Protocols, Wireless, Docker, Software Architecture, Microservices, Technical Leadership, Startups, Scalability, React Native, App Store, Subscriptions, User Interface (UI), Core Animation, User Experience (UX), Cocoa Touch, REST APIs, Codable, iPad, Image Manipulation, Video Editing

Data Engineer

2018 - 2020

Tovala

Developed data pipelines to lay out foundations for data intelligence to drive business decisions. Python and SQL.
Developed dashboards and scripts to show insights about company performance.
Developed data science models for meal sales predictions using Ridge Regression Model.

Technologies: Python 3, Software Architecture, Startups, Scalability, Video Editing

Software Engineer

2017 - 2018

Movella

Developed internal management software using Node.js and SQL for managing hardware device inventory.
Developed a motion tracking algorithm using MATLAB to visualize the motion trajectory of the latest sensor technologies.
Improved the company process by setting up system design review processes.

Technologies: SQL, Node.js, Video Editing

Technical Evangelist

2016 - 2017

Microsoft

Developed chatbot applications for retailers to resolve customer queries using Microsoft Intelligence Services.
Developed multiple proofs of concepts using the latest Microsoft technologies.
Spoke at multiple conferences across universities and technical communities.

Technologies: Node.js, Video Editing

Experience

Quintics

https://testflight.apple.com/join/61g11YYa

A financial portfolio application that allows users to connect to their stock exchange, crypto exchange, and decentralized wallet accounts and summarize asset information in user‑friendly dashboards.

I am the founder and developer of the application.

Wombat Exchange

https://app.wombat.exchange/

Wombat Exchange is a multi-chain stable-swap platform that allows users to swap stable coins at minimal slippage and stake at maximum yield.

I've contributed to the project as a DApp engineer, frequently interacting with smart contract developers.

Cryptocurrency Price Tracker

https://github.com/graysonhyc/BraveWalletHack

An iOS mobile app built with SwiftUI and The Composable Architecture (TCA). Users can track real-time crypto-currency prices and their daily percentage changes. The price data is fetched from the CoinGecko API.

Conflict-free Replicated Data Type in Python

https://github.com/graysonhyc/lww_elements_set_py

Implemented a last-write-wins (LWW) element set data structure and an operation-based conflict-free replicated data type (CDRT) in Python. A test suite was also included to test various CDRT properties, i.e., commutativity, associativity, and idempotence.

Skills

Languages

Swift 5, TypeScript, Swift, Swift 2, Swift 3, CSS, HTML, Dart, Kotlin, Objective-C, JavaScript, Solidity, Python 3, Go, SQL

Frameworks

SwiftUI, iOS SDK, Flutter, UIKit, React Native, Angular, Next.js, Core Data, Cocoa Touch, Redux

Libraries/APIs

React, RxSwift, Node.js, WebRTC, Core Animation, REST APIs, Codable, Core Image

Tools

Xcode, GitHub, Atlassian, Jira, Figma, CircleCI, TestFlight, CallKit, Moya, Prisma

Paradigms

Model View Viewmodel (MVVM), Agile Project Management, Mobile Development, Requirements Analysis, Test-driven Development (TDD), Automated Testing, Microservices, Agile, DevOps

Platforms

MacOS, iOS, Mobile, Android, Firebase, Google Cloud Platform (GCP), Docker, Amazon Web Services (AWS), Azure

Industry Expertise

Project Management

Other

Mobile Apps, Native Mobile Apps, Product Management, Front-end, Project Planning, Product Strategy, APIs, Architecture, Combine, Amazon RDS, Full-stack, Animation, A/B Testing, CI/CD Pipelines, Team Leadership, Video Chat, Wireless Protocols, Software Architecture, eCommerce, Technical Leadership, Startups, Scalability, Planning, Finance, App Store, Subscriptions, User Interface (UI), User Experience (UX), UI Animation, WebSockets, Video Streaming, Web Development, iPad, Image Manipulation, Video Editing, AVFoundation, Virtual Reality (VR), Non-fungible Tokens (NFT), Data Structures, Wireless, Widgets

Storage

MongoDB, Cloud Firestore

Education

2012 - 2016

Bachelor's Degree in Computer Science

University of Hong Kong - Pokfulam, Hong Kong

2014 - 2015

Student Exchange Program in Computer Science

Yale University - New Haven, CT, USA