Grayson Ho, Developer in London, United Kingdom
Grayson is available for hire
Hire Grayson

Grayson Ho

Verified Expert  in Engineering

iOS Developer

Location
London, United Kingdom
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.

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

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 - 2024
Revolut
  • Led an 8-person team to develop a joint account 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.
  • Built the Safari extension for the Revolut card wallet.
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, Augmented Reality (AR), Blockchain, Decentralized Applications, Decentralized Systems, MetaMask, Web3, Safari Extensions, Safari, SDK Development, SDKs, Software Development Toolkits (SDK), Bluetooth, GraphQL

Senior DApp Engineer

2021 - 2023
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 $20 million of total value locked and a record of $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, Decentralized Applications, SDK Development, SDKs, Software Development Toolkits (SDK), Bluetooth, GraphQL

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), Blockchain, Web3

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, SDK Development

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

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.
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

Libraries/APIs

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

Tools

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

Frameworks

SwiftUI, iOS SDK, Flutter, UIKit, React Native, Combine, Angular, Next.js, Core Data, Cocoa Touch, Redux, Unity, iOS SceneKit, AWS HA, ARKit

Languages

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

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, Blockchain, Android, Firebase, Google Cloud Platform (GCP), Docker, Amazon Web Services (AWS), Azure, Desktop, Safari

Industry Expertise

Project Management

Storage

MongoDB, Cloud Firestore

Other

Mobile Apps, Native Mobile Apps, Product Management, Front-end, Project Planning, Product Strategy, APIs, Architecture, Decentralized Applications, Decentralized Systems, Web3, 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), iOS Camera, Safari Extensions, Minimum Viable Product (MVP), SDK Development, SDKs, Software Development Toolkits (SDK), Data Structures, Wireless, Widgets, 3D Modeling, Augmented Reality (AR), Objective-C++, Instant Messaging, PSD to Swift, Bluetooth

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