Joseph is available for hire
Hire JosephJoseph Saw
Verified Expert in Engineering
Blockchain Developer
Kuala Lumpur Federal Territory of Kuala Lumpur, Malaysia
Toptal member since August 30, 2022
Bio
Joseph is an experienced full-stack developer who has worked on various projects, including crypto payment solutions and decentralized yield tokenization and trading. In his spare time, he occasionally works on arbitrage bots and, most recently, created YouTube videos to provide education on smart contracts and solidity.
Portfolio
Apex Core LLC
Blockchain, JavaScript, React, Rust, Solana, Smart Contracts...
CENSORED STUDIO.CO
Solidity, Blockchain, HTML, JavaScript, CSS, HTML5, ZK, React...
Floki Web Solutions
Blockchain, Decentralized Finance (DeFi), Cryptocurrency, Solidity...
Experience
- Vue - 8 years
- Hardhat - 5 years
- TypeScript - 5 years
- Ethers.js - 3 years
- Ethereum - 3 years
- Decentralized Finance (DeFi) - 3 years
- Smart Contracts - 3 years
- Solidity - 3 years
Preferred Environment
TypeScript, Vue, Solidity, Ethereum, Hardhat, Smart Contracts, ERC-20, Non-fungible Tokens (NFT), Cryptocurrency Wallets, Decentralized Finance (DeFi), GitHub, OpenZeppelin
The most amazing...
...product I've built is a trading bot handling $200 million of trading volume.
Work Experience
Full-stack Blockchain Developer (Solana/Rust and React)
2025 - 2026
Apex Core LLC
- Shipped Anthropic Claude-powered AI chat (including persisted chat rooms and context) so users can interact with health-related context in natural language.
- Delivered a React and TypeScript (Vite) app with separate patient and provider dashboards, centralized routing, and Solana wallet connectivity via WalletConnect/AppKit.
- Developed Anchor Solana programs and devnet deployment workflows aligned with mock USDC minting and the front end’s Solana configuration.
- Built a NestJS and MongoDB healthcare back end with modular domains for users, health records, appointments, claims, providers, and organizations.
- Implemented OwlPay payment and transfer flows with webhook handling, plus SendGrid email and Twilio Verify for account verification.
- Integrated the REDOX FHIR API (OAuth and legacy key auth) to create patients, sync observations, and persist FHIR IDs alongside local user records.
- Authored internal REDOX workflow and FHIR integration documentation for registration, records, and cross-system handoffs.
- Prepared AWS App Runner deployment guidance with environment variables and CORS configuration for production-style hosting of the API.
Technologies: Blockchain, JavaScript, React, Rust, Solana, Smart Contracts, Cryptocurrency Wallets, SOC 2, HIPAA Compliance, CI/CD Pipelines, Amazon Web Services (AWS), API Integration, Bitcoin, Web3.js, Docker, REST APIs, NestJS
Solidity and React Developer
2025 - 2025
CENSORED STUDIO.CO
- Collaborated directly with the founder to translate product requirements into deployable smart contracts and front-end features, accelerating delivery by leveraging existing reference implementations instead of greenfield builds.
- Developed a decentralized “Up & Down” ETH price prediction game using off-chain price feeds with ZK proofs to cryptographically verify multi-CEX price data, preventing outcome manipulation and enabling user-verifiable results.
- Designed a modular PvP and pooled escrow system with configurable house fees (3–5%), deterministic payout logic, and trust-minimized fund custody, reducing counterparty risk to zero during gameplay.
- Audited and hardened smart contract logic against common vulnerabilities (reentrancy, incorrect fee accounting, unsafe external calls), improving overall protocol safety prior to production deployment.
- Integrated third-party APIs (e.g., ChangeNOW) to enable seamless token swaps directly within the dApp, improving user conversion and reducing friction between gameplay and liquidity access.
Technologies: Solidity, Blockchain, HTML, JavaScript, CSS, HTML5, ZK, React, Ethereum Smart Contracts, zkSNARKs, APIs, Ethereum Virtual Machine (EVM), Binance API, Coinbase API, Smart Contracts, Remix IDE, Remix, Stablecoins, ÐApp, Etherscan, Web3, Project Planning, API Integration, Web 3.0, SOC 2, CI/CD Pipelines, HIPAA Compliance, Docker, REST APIs, NestJS
Senior Solidity Developer (via Toptal)
2023 - 2024
Floki Web Solutions
- Engineered and deployed tokenization contracts, empowering users to create customized ERC-20, ERC-721, and ERC-1155 tokens with unique features like buyback, reflection, burn, transfer fees, and a public mint fee.
- Led discussions and reviews with CertiK's audit team, contributing to the overall security and reliability of the tokenization platform.
- Advised and collaborated with clients to develop MEV-resistant trading and sniping bots, enhancing their ability to navigate and operate efficiently in dynamic blockchain environments.
- Ensured that bonding filled will automatically deploy liquidity to UNIV2 DEXs.
Technologies: Blockchain, Decentralized Finance (DeFi), Cryptocurrency, Solidity, Smart Contracts, Ethereum, Ethers.js, Etherscan, Ethereum Smart Contracts, Bitcoin, Binance API, Bots, ÐApp, BNB Smart Chain, Test Scripting, Foundry, Truffle, Decentralized Exchanges (DEXs), Remix IDE, Figma, Full-stack, GitHub, OpenZeppelin, Solana, Rust, API Integration, CI/CD Pipelines, Stablecoins, Ethereum Virtual Machine (EVM), Web3, Web 3.0, HTML5, Docker, REST APIs, NestJS, PostgreSQL
Blockchain Trading-bot Expert
2023 - 2023
The People's Movement Corp.
- Improved their existing bot algorithm to allow unlimited token pairs to be monitored without needing an expiration time, giving better reliability and options to buy/sell a token.
- Debugged and fixed an issue with their bot sending multiple ERC-20 approval transactions.
- Onboarded by the client to help resolve several issues with their existing decentralized finance sniper trading bot.
Technologies: Blockchain, Bots, Trading, Decentralized Finance (DeFi), Binance API, Cryptocurrency, Amazon Web Services (AWS), APIs, ERC-20, Web3.js, Web3, BNB Smart Chain, Test Scripting, Foundry, Truffle, Figma, Full-stack, GitHub, Telegram Bot API, Telegram Bots, Decentralized Exchanges (DEXs), OpenZeppelin, Permit2, Remix IDE, Remix, Stablecoins, Ethereum Virtual Machine (EVM), ÐApp, Etherscan, API Integration, Web 3.0, CI/CD Pipelines, HTML5, Docker, REST APIs, NestJS, PostgreSQL
Product Manager Consultant
2022 - 2023
Hex Trust
- Researched methodologies to maintain the peg of USDX, ensuring stablecoin stability and reliability.
- Led the research, SOP development, and setup of monitoring and alerting software (OpenZeppelin Defender) to oversee on-chain activities of USDX, ensuring real-time response against potential hacks.
- Designed the Gas Station feature to automatically fund wallet addresses for transactions with insufficient gas, improving user experience and transaction efficiency.
- Managed a team of developers in building new features, ensuring timely delivery and alignment with company goals.
- Led the deprecation of Goerli, transitioning to Sepolia testnet for Ethereum, enhancing product demo reliability and functionality.
Technologies: Crypto, DApps, Stablecoins, Blockchain, Ethereum, Ethereum Virtual Machine (EVM), Decentralized Finance (DeFi), Cryptocurrency, Cryptocurrency Wallets, Figma, Full-stack, GitHub, Decentralized Exchanges (DEXs), OpenZeppelin, Etherscan, API Integration, Web 3.0, CI/CD Pipelines, HTML5, REST APIs
Senior Web3 Front-end and Solidity Developer
2022 - 2023
HypeFun
- Led the development of a crypto ERC20 Launchpad that enables users to create and launch memecoins using Uniswap bonding curves, facilitating fair token distribution and on-chain liquidity management.
- Designed a scalable transaction batching and event handling mechanism that enabled the platform to raise over $75,000 in its public presale within minutes, processing thousands of on-chain transactions without downtime.
- Integrated AI agent creation tools, allowing users to generate and personalize AI-driven agents that represent and promote their memecoins across social platforms.
- Planned the architecture of a decentralized application using Vue.js and TailwindCSS, deployed using Kubernetes on AWS, delivering seamless token deployment and AI agent interaction directly on the browser.
- Designed and implemented real-time analytics dashboards to monitor token performance, liquidity, and AI engagement metrics.
- Built Mocha/Jest test suites to ensure reliability and performance across key workflows.
Technologies: APIs, Vue, Smart Contracts, Ethereum Smart Contracts, Solidity, Project Planning, Ethers.js, TypeScript, JavaScript, Ethereum, Netlify, Web3.js, Subgraph, Blockchain, Chai, Testing, Mocha, Git, Web, Hardhat, Crypto, Tokenomics, Cybersecurity, Cryptocurrency Wallets, Node.js, CSS, HTML, Blockchain Platforms, Blockchain Design, Decentralized Autonomous Organizations (DAO), Decentralized Finance (DeFi), Cryptocurrency, DApps, Cryptocurrency APIs, Web Development, Fintech, Cryptoeconomics, Tailwind CSS, MetaMask, Decentralization, Tokenization, TradingView, ERC-20, Web 3.0, Front-end, Web3, Front-end Development, ÐApp, BNB Smart Chain, Test Scripting, Foundry, Truffle, Figma, Full-stack, GitHub, Decentralized Exchanges (DEXs), OpenZeppelin, Permit2, Kubernetes, Amazon Web Services (AWS), Ethereum Virtual Machine (EVM), Etherscan, API Integration, CI/CD Pipelines, HTML5, Docker, REST APIs, NestJS, PostgreSQL
Blockchain Trading-bot Expert
2022 - 2022
The People's Movement Corp.
- Implemented a custom trading view indicator using Pine Script to send alerts to a Firebase back end once strategy parameters have been met. This will ping the trading bot to determine whether to execute the trade.
- Architected a composable data structure to allow for a custom number of price sources, dynamic take profit and stop losses, and price source weightages.
- Built an admin dashboard using Vue, TypeScript, and Firebase for ease of use for non-technical users, allowing the admin to manage positions and symbols to trade.
- Integrated Binance API to allow the bot access to a centralized exchange to execute trades on.
- Hosted the bot on Heroku for reliable uptime, logs, and pushing updates via their custom Heroku Git command line interface.
Technologies: Blockchain, Bots, Trading, Decentralized Finance (DeFi), Binance API, Cryptocurrency, Pine Script, Heroku, Arbitrage, Fintech, Cryptoeconomics, Cryptocurrency APIs, Firebase, Tokenization, TradingView, ERC-20, Front-end, Web3.js, Web3, ÐApp, BNB Smart Chain, Test Scripting, Foundry, Truffle, Figma, Full-stack, AWS Amplify, GitHub, Decentralized Exchanges (DEXs), OpenZeppelin, Ethereum Virtual Machine (EVM), Etherscan, API Integration, Web 3.0, HTML5, Docker, REST APIs, NestJS, PostgreSQL
Blockchain Engineer
2020 - 2022
Pendle
- Developed a blockchain monitoring service using Subgraph and GraphQL to monitor the prices of yield, fluctuating interest rates, and user rewards, implementing a dashboard to display the data.
- Integrated all Solidity smart contract logic to the UI, allowing users to tokenize their yield into an ERC-20 token, trade it, and collect rewards. This was launched on Ethereum Mainnet with a total transaction volume of over $30 million.
- Designed SOPs for UI developers to deploy a local blockchain and Pendle protocol on their machines for development and testing.
- Implemented and deployed a UI using Vue, Tailwind CSS, Ethers, and Netlify.
- Built a landing page for the ICO of our ERC-20 token, seeing $10 million in total sales within the first hour of launching.
- Researched multiple blockchains to help the team decide on the second blockchain to deploy our smart contracts, expanding our protocol and going multi-chain.
Technologies: Ethereum, Ethers.js, Vue, Netlify, Web3.js, Subgraph, Git, Mocha, Testing, Chai, Hardhat, Ethereum Smart Contracts, Blockchain, Tokenomics, Crypto, Cybersecurity, Solidity, Smart Contracts, APIs, Node.js, CSS, HTML, Blockchain Design, Blockchain Platforms, Decentralized Autonomous Organizations (DAO), ERC-721, Decentralized Finance (DeFi), Bots, Trading, Cryptocurrency, DApps, Web Development, Cryptocurrency APIs, TypeScript, Web, Cryptocurrency Wallets, Fintech, Cryptoeconomics, GraphQL, Tailwind CSS, MetaMask, Decentralization, Tokenization, TradingView, ERC-20, Front-end, Web3, Front-end Development, ÐApp, BNB Smart Chain, Test Scripting, Foundry, Truffle, Figma, Full-stack, GitHub, OpenZeppelin, Ethereum Virtual Machine (EVM), Etherscan, API Integration, HTML5, Docker, REST APIs
Lead Developer
2019 - 2020
Sellcrowd
- Developed an MVP on WordPress within a month, resulting in the first 100 job posts.
- Rebuilt MVP to a standalone WebApp on Nuxt.js and Firebase back end within three months.
- Implemented functionalities from account creation, posting, and applying to jobs, live messaging, hiring, contract management, and payments and payouts using Stripe.
Technologies: Firebase, Vue, JavaScript, Serverless Architecture, Nuxt.js, Git, SendGrid, SendGrid API, WordPress, Cybersecurity, Team Leadership, Netlify, APIs, Node.js, React, CSS, HTML, Bots, Web Development, Web, Front-end, Front-end Development, Test Scripting, Figma, Full-stack, AWS Amplify, GitHub, API Integration, HTML5, Docker
Full-stack Developer
2018 - 2019
ThunderQuote
- Developed a drag-and-drop dashboard to manage procurements for multiple levels of an organization, making it easy for large teams to understand where they're at in the procurement stage and simplify the approvals and review process.
- Refactored several sections of PHP code to follow the updated best practices set by the CTO. Resulting in more readable and efficient code.
- Created an email subscription service using a PHP back end and SendGrid integration, sending out thousands of emails monthly.
Technologies: jQuery, WordPress, Vue, Amazon Web Services (AWS), Git, SendGrid, SendGrid API, Cybersecurity, APIs, Node.js, React, CSS, HTML, Bots, Web Development, Web, Front-end, Front-end Development, Test Scripting, Figma, Full-stack, AWS Amplify, API Integration, HTML5, Docker, REST APIs
Experience
Triangular Arbitrage Bot
https://snowtrace.io/tx/0x5a1b5675719f55e586e39e28166cf3d86bf1c80c852a98be688468a239c66615A triangular arbitrage bot that monitors the blockchain for specific transactions that interact with decentralized exchanges.
Once found, it checks the trade volume to see if it will cause a significant enough price impact to create an arbitrage opportunity. If so, it will immediately calculate the best possible path for profit and submits the transaction.
Once found, it checks the trade volume to see if it will cause a significant enough price impact to create an arbitrage opportunity. If so, it will immediately calculate the best possible path for profit and submits the transaction.
GamePay
A crypto payment gateway solution for the online gaming industry. Planned and developed a scalable serverless back-end architecture to monitor various blockchains for transactions with minimal downtime.
Built a front-end dashboard for projects to manage and monitor relevant data like deposits, withdrawals, and user and historical data.
Built a front-end dashboard for projects to manage and monitor relevant data like deposits, withdrawals, and user and historical data.
Web VR
I was a sub-contractor for this project. I developed a WebVR environment for the National Heart Institute of Malaysia to showcase its hospital services and facilities.
Using 360-degree images provided by the primary contractor of the hospital, I stitched it together using Marzipano, then created the pop-up and enlightening experience using jQuery.
Using 360-degree images provided by the primary contractor of the hospital, I stitched it together using Marzipano, then created the pop-up and enlightening experience using jQuery.
Ethereum Units Converter
I frequently use online tools to help me to do big numbers of conversions when developing Smart Contracts.
Unfortunately, the existing tooling is very restrictive and does not support custom decimals, so I built my tool and released it to the Ethereum community.
Unfortunately, the existing tooling is very restrictive and does not support custom decimals, so I built my tool and released it to the Ethereum community.
Education
2015 - 2018
Bachelor of Security and Forensics in Computer Science
Taylor's University - Subang Jaya, Malaysia
Skills
Libraries/APIs
Vue, Web3.js, Chai, jQuery, Node.js, OpenZeppelin, REST APIs, SendGrid API, React, Binance API, AWS Amplify, Telegram Bot API, Coinbase API, WebVR
Tools
Mocha, MetaMask, Etherscan, Remix IDE, Figma, GitHub, Git, SendGrid
Languages
Solidity, TypeScript, JavaScript, CSS, HTML, HTML5, Rust, Pine Script, GraphQL
Frameworks
Hardhat, Truffle, Remix, NestJS, Nuxt.js, ZK, Tailwind CSS
Paradigms
Testing, HIPAA Compliance, Serverless Architecture
Platforms
Ethereum, Netlify, Blockchain, Web, Blockchain Platforms, Docker, WordPress, Decentralized Exchanges (DEXs), Kubernetes, Amazon Web Services (AWS), Heroku, Firebase
Industry Expertise
Cybersecurity
Storage
PostgreSQL
Other
English, Smart Contracts, Ethers.js, Subgraph, Ethereum Smart Contracts, Non-fungible Tokens (NFT), Crypto, Tokenomics, APIs, Blockchain Design, Decentralized Autonomous Organizations (DAO), ERC-721, Decentralized Finance (DeFi), Bots, Cryptocurrency, DApps, Cryptocurrency APIs, Web Development, Fintech, Cryptoeconomics, Decentralization, Tokenization, TradingView, ERC-20, Web 3.0, Front-end, Web3, Front-end Development, ÐApp, BNB Smart Chain, Test Scripting, Stablecoins, Ethereum Virtual Machine (EVM), Full-stack, Permit2, API Integration, Project Planning, Cryptocurrency Wallets, Team Leadership, Trading, Foundry, Telegram Bots, Solana, CI/CD Pipelines, zkSNARKs, SOC 2, Arbitrage, Bitcoin
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