David ZC

- Developed and maintained smart contracts and backend services for a blockchain wallet application - Maintained and optimized ERC-4337 (Account Abstraction) smart accounts, including a custom Paymaster contract - Implemented EIP-7702 smart contracts to enable gasless transactions - Integrated social login authentication using AWS Cognito (Google, Facebook, Apple) - Built and maintained backend services for price alerts, token features, and a custom indexer to collect chart and trade data - Integrated fiat on-ramp/off-ramp solutions via MoonPay and Onramper - Designed and deployed ERC-4626 vaults, implementing lending and borrowing strategies to generate yield - Researched emerging blockchain standards and technologies to improve product capabilities - Improved system reliability and scalability for services supporting thousands of users

Zuni Lab – Innovating in Blockchain Since University Since my university days, my friends and I have been passionate about building innovative blockchain-based products. To pursue this vision, we founded Zuni, a research and development lab focused on exploring blockchain technology. Through hackathons and competitions, we continuously challenge ourselves, push technological boundaries, and build impactful solutions. Our dedication has earned us multiple awards, and we remain committed to researching and developing groundbreaking projects in the Web3 space. Highlighted Projects: 1/ Dexon: Bringing CEX-level trading to DeFi with AI-powered assistance. 2/ Smart Vault: A secure vault system for controlled rewards distribution. 3/ ZUNI: Empowering privacy-conscious identity verification. Control your data securely with decentralized identifiers and verifiable credentials. Verify with zk-SNARKs 4/ Zswap: A fully decentralized concentrated liquidity DEX, enabling trustless trading. 5/ ICXplorer: A smart contract explorer for developers on the ICON blockchain. 6/ Donapp: A simple donation dApp built on Near. 7/ SunID: Securely manage and verify real-world data using the power of blockchain on Tron

Worked as a full-stack blockchain engineer to build a Layer 1 chain that enables Bitcoin interoperability by modules such: 1/ Scalar Core (Go, Cosmos SDK, Protobuf, gRPC) - Developed a Layer 1 blockchain using Cosmos SDK, alongside a robust Bridge Chain inspired by Axelar's cross-messaging, to create a foundational interoperability layer for seamless and secure communication between Bitcoin and EVM-compatible chains. - Make the design of custom modules, Bitcoin transaction validators, and message passing logic. - Handled core ABCI lifecycle, including block processing, messages voting, and event emission of cross-chain modules 2/ Bitcoin Vault (Rust, FFI, WASM, JavaScript) - Architected and built a secure Bitcoin vault library in Rust featuring staking, redeeming, and multisig functionalities using Taproot, Schnorr, HTLCs, and Bitcoin Script. - Extended the rust-bitcoin library to enable flexible PSBT signing. - Created WebAssembly and FFI bindings to support integration with Go and JavaScript environments. - Processing MuSig2 for threshold signing and secure coordination among vault participants. 3/ EVM Contracts (Solidity, Foundry): - Developed and maintained EVM gateway contracts, extended from Axelar’s codebase, to facilitate cross-chain message passing between Bitcoin, Cosmos, and EVM-compatible chains. 4/ Relayer, Indexer, Developer Tools (Rust, Go, Postgres): - Built a cross-chain relayer to orchestrate message delivery between networks. - Implemented a custom Electrum-based Bitcoin indexer in Rust for Scalar's vault transaction tracking. - Created CLI tools and testing frameworks to validate high-throughput scenarios and simulate cross-chain workflows. - Developed Go services for backend APIs and integrated client-facing functionality like wallet connections, contract calls, and message signing. 5/ DevOps & Deployment (Docker, Bash): Seup deployment of multi-service architecture using Docker and Bash scripts.

Multichain Wallet - Built a multichain wallet supporting Ethereum, Gala, and TON, with full control over both backend cryptographic logic and frontend user interface. - Implemented cryptographic features in TypeScript, including HD wallet derivation, encrypt, decrypt, signing, verifying, and secure key management. Developed wallet connection and transaction signing for Ethereum and TON using ethers.js and TON SDKs. - Integrated Gala support by designing and implementing custom wallet methods. Built a Chrome extension wallet UI using React, including popup interface, injected scripts, and background communication layers. - Implemented browser extension architecture, enabling secure communication between popup, background, and dApps via content scripts. - Designed a smooth UX for multichain users, supporting address management, signing flows, and chain-specific features. Tech Stack: JS libraries, TypeScript, React, Ethers.js, Gala SDK, TON libraries, Chrome Extension APIs

Kham Benh – Public Healthcare Frontend Project: Kham Benh - Developed the user interface for a public health service platform, aiming to improve accessibility and efficiency for both patients, doctors, practitioners, nurses, pharmacies and administrators. - Built responsive and accessible frontend pages using Next.js, supporting both desktop and mobile experiences. - Implemented UI features such as patient registration, appointment booking, medical records display, and health service listings. - Integrated REST APIs to fetch and display dynamic healthcare data. - Focused on performance optimization using code-splitting, lazy loading, and server-side rendering. Technology Stack: Next.js

Led the development of a privacy-first healthcare platform with full end-to-end encryption to protect sensitive user data. Project: Cherubim - Defined product requirements, data models, and privacy specifications for secure healthcare data handling. - Built the backend architecture using Go and MongoDB, and set up the base Flutter mobile frontend. Managed mobile authentication flows and integrated Web3Auth for secure, user-friendly login. - Implemented end-to-end encryption to ensure data privacy across backend and mobile layers. - Integrated OpenTelemetry for system observability, including monitoring, tracing, and performance metrics. - Set up CI/CD pipelines to automate testing, building, and deployment on AWS. Technology stack: Golang, Web3Auth, MongoDB, Flutter, OpenTelemetry, AWS, Redis

Pharmatech CRM Technology stack: GRPC, Golang, MongoDB, NextJS, Docker, GitHub Actions - Developed an internal CRM system for Pharmatech, managing products, orders, users, and ad campaigns. - Worked closely with cross-functional teams to align with business objectives. - Developed gRPC nodes in a microservices architecture for seamless API-driven communication. - Designed and optimized MongoDB schemas for efficient and scalable data storage. - Implemented cron jobs to automate data collection from Facebook and Google Ads for targeted marketing insights. - Orchestrated CI/CD pipelines with Docker and GitHub Actions for streamlined development and reliable deployment

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