Julian Cislo, Developer in Oshawa, Canada
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Julian Cislo

Verified Expert  in Engineering

Blockchain Developer

Oshawa, Canada
Toptal Member Since
October 6, 2022

Julian is a full-stack Web 3.0 developer and consultant. He specializes in solidity smart contracts design, development, and security considerations. He has founded QuantDeFi, a consulting company in the blockchain space that offers to solve all Web 3.0-related problems for clients looking to integrate blockchain solutions. Julian also features his skills in transaction automation, having constructed arbitrage and liquidation bots utilizing flash-loan technologies.


QuantDEFI consulting
JavaScript, TypeScript, Bots, Complex Problem Solving, Solidity, Truffle...
UE Games
Blockchain, Smart Contracts, Solidity, Ethereum, JavaScript, Cryptocurrency...
Freelance Client
JavaScript, Node.js, Python, Cryptocurrency, Blockchain, Binance API...




Preferred Environment

Windows, Ubuntu, MacOS, TypeScript, Solidity, Truffle, Hardhat, NPM, JavaScript, Non-fungible Tokens (NFT), Blockchain, MetaMask

The most amazing...

...protocol I've built is a P2P NFT lending service with tradeable NFT derivatives.

Work Experience


2021 - PRESENT
QuantDEFI consulting
  • Developed full-stack blockchain applications for various projects.
  • Created bot systems for blockchain transaction automation, including trading bots, arbitrage, and liquidations.
  • Audited smart contract code for various clients, seeking common and uncommon potential security exploits and gas optimizations.
Technologies: JavaScript, TypeScript, Bots, Complex Problem Solving, Solidity, Truffle, Hardhat, Non-fungible Tokens (NFT), Blockchain, Smart Contracts, MetaMask, Full-stack Development, Management, Uniswap, Lending, Windows, Arbitrage, Blockchain & Cryptocurrency, Python, Full-stack, Tokenomics, ERC-721, ERC-1155, ERC-20, Project Management, Oracle, Foundry, Git, APIs, Utility Tokens, Web3, Token Design, Ganache, Ganache CLI, Writing & Editing

Web3.js Engineer

2020 - PRESENT
UE Games
  • Developed and deployed NFT solutions to be distributed to hundreds of gamers.
  • Designed and implemented tokenomics systems for various fungible tokens.
  • Consulted and advised about several scaling options, including Polygon and ImmutableX, to improve transaction speeds and costs.
Technologies: Blockchain, Smart Contracts, Solidity, Ethereum, JavaScript, Cryptocurrency, Software Architecture, Bots, Decentralized Finance (DeFi), Crypto, Node.js, Security, Solana, Non-fungible Tokens (NFT), MetaMask, Full-stack Development, HTML, CSS, Windows, Blockchain & Cryptocurrency, Full-stack, Tokenomics, ERC-721, ERC-20, TypeScript, Project Management, SQL, Oracle, Foundry, Git, APIs, Utility Tokens, Web3, Token Design, Ganache, Ganache CLI, Writing & Editing

Trading Bot Developer

2022 - 2022
Freelance Client
  • Developed on-chain trading business logic and implemented it into a Node.js back end paired with a MySQL database.
  • Created API and WebSocket endpoints for live data feeds and direct connection to the front end.
  • Expanded the system for commercial use, enabling multiple users to access it simultaneously.
  • Utilized various decentralized finance liquidity pool protocols such as Uniswap.
Technologies: JavaScript, Node.js, Python, Cryptocurrency, Blockchain, Binance API, Full-stack, ERC-20, SQL, Git, APIs, Utility Tokens, Web3, Token Design, Ganache, Ganache CLI

Senior Full-stack Developer

2021 - 2022
  • Created the peer-to-peer NFT collateralization protocol.
  • Integrated advanced Solidity concepts, including in-line assembly and upgradable contracts.
  • Managed a small team of developers to create promotional NFTs and minting UI.
Technologies: Full-stack Development, Solidity, JavaScript, Truffle, Creative Problem Solving, Management, Web Marketing, Twitter, Blockchain, Smart Contracts, Cryptocurrency, Software Architecture, Trading, Decentralized Finance (DeFi), Crypto, Node.js, Security, Non-fungible Tokens (NFT), MetaMask, HTML, CSS, Windows, Blockchain & Cryptocurrency, Full-stack, ERC-721, ERC-20, Project Management, SQL, Oracle, Git, APIs, Utility Tokens, Web3, Token Design, Ganache, Ganache CLI

Smart Contract Engineer

2020 - 2021
Freelance Client
  • Developed an experimental stablecoin backed by liquidity pool tokens, including uniswap and balancer.
  • Utilized Chainlink Oracle feeds for the valuation of liquidity tokens and to determine stablecoin issuance.
  • Anticipated achieving a stablecoin without needing a liquidation mechanism.
  • Faced the challenge of ensuring the peg remained in cases of extreme divergence loss.
Technologies: Blockchain, JavaScript, Solidity, Truffle, Hardhat, Uniswap, Smart Contracts, Ethereum Smart Contracts, Ethereum, MetaMask, Full-stack Development, Management, Lending, Windows, Blockchain & Cryptocurrency, Python, Full-stack, Tokenomics, ERC-1155, ERC-20, Project Management, Oracle, Foundry, Git, APIs, Utility Tokens, Web3, Token Design, Ganache, Ganache CLI, Writing & Editing

Lotto Balls

Lotto Balls is a smart contract slot machine and lottery game utilizing Chainlink VRF to provide secure random numbers where I designed, developed, tested, and launched the front end with React and back end using Solidity Smart Contracts.

The game's goal is to select eight digits from 1 to 8 each and then attempt to match them with a randomly generated set. The more digits match, the greater the prize. The protocol also contains a native fungible token that is minted as a prize and enables an alternative way to play the game. The game is live on Polygon and requires MetaMask pointed at the polygon network to access the application.

Arbitrage, Liquidation, and Other Miscellaneous Transaction Automation Tools

As a hobby, I enjoy developing various bots to perform on-chain arbitrage, liquidations, and other potentially profitable tasks and my preferred toolset for development is Node.js for monitoring scripts, Web3.js for connections to the blockchain, and Truffle and Solidity for all smart contract needs.

Some bots, such as single-protocol arbitrage or NFT-game automation, are simple because they only require a monitoring script and direct interaction with existing protocols. In other cases, like multi-protocol arbitrage and liquidations, I have written custom smart contracts to combine multiple on-chain actions into single transactions. Common design patterns include using flash loans or flash-like designs to integrate various function calls into a single atomic action. For most automation tasks, fast and reliable access to a node is necessary; therefore, I opt to run my blockchain nodes locally to bypass public RPC rate limits.

I have experience operating nodes on Ethereum, Avalanche, Harmony, Polygon, Optimism, Binance Smart Chain, and Fantom.


Rentable is an NFT rental platform enabling users to rent out their NFTs to borrowers for a fee. To rent an available NFT, the borrower must first put down collateral and pay a fee to the owner to receive the NFT. If the token is not returned on time, the collateral is returned to the NFT owner. This project was developed at the ETHToronto hackathon and constructed in under 24 hours.

Caesar's Temple

Caesar's Temple is a Web 3.0 game universe based on Greek and Roman mythology. It features role-playing elements, including combat, resource gathering, and crafting, among other things. This game is built entirely of smart contracts and utilizes VRF to bring secure randomization in a decentralized system. It also features my unique experimental token-omic systems and will follow a modular release schedule.
2010 - 2015

Bachelor of Science in Physics

University of Guelph - Guelph, Ontario, Canada


Blockchain Development

George Brown College


Web3.js, React, Node.js, Binance API


NPM, MetaMask, Git, Ganache, Ganache CLI


Truffle, Hardhat


TypeScript, Solidity, JavaScript, Python, HTML, CSS, SQL, Python 3, Java, C++


Windows, Blockchain, Ethereum, Oracle, Ubuntu, MacOS, Hyperledger, Twitter

Industry Expertise

Project Management




Complex Problem Solving, Creative Problem Solving, Ethereum Smart Contracts, Smart Contracts, Cryptocurrency, Bots, Decentralized Finance (DeFi), Crypto, Lending, Security, Non-fungible Tokens (NFT), Uniswap, Arbitrage, Blockchain & Cryptocurrency, Full-stack, Tokenomics, ERC-721, ERC-1155, ERC-20, APIs, Utility Tokens, Polygon, Web3, Token Design, Full-stack Development, Software Architecture, Trading, Solana, Foundry, Writing & Editing, Web Marketing, User Experience (UX), Physics, Mathematics, Computer Science, Education, Training

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