Octavian is available for hire

Octavian Lojnita

Verified Expert in Engineering

Full-stack Developer

Location

Constanța, Romania

Toptal Member Since

April 22, 2022

Octavian, an accomplished software polymath, has 20+ years of experience in networking, security, apps, websites, blockchains, and emerging technologies like AI. His expertise in app development, iOS games, custom web systems, and fintech has propelled numerous projects to success in both the Web 2.0 and Web 3.0 realms. Leveraging his profound knowledge, Octavian pushes the frontiers of blockchain technologies, fostering innovation within all his expertise.

Portfolio

Progressive Web Apps

Blockchain, Cryptocurrency, Non-fungible Tokens (NFT), ICO, Sidechains...

Psalm, LLC (dba Psalm DAO)

Blockchain, Smart Contracts, CTO, Non-fungible Tokens (NFT), Cryptocurrency...

Opus Momentus Proprietary Limited

Blockchain, Tokenomics, Cryptocurrency Wallets, Product Growth, SQL, Oracle...

Experience

Full-stack - 10 years Blockchain - 10 years Ethereum - 8 years DApps - 8 years Solidity - 8 years Audits - 7 years React - 7 years Decentralized Finance (DeFi) - 5 years

Availability

Full-time

Preferred Environment

Solidity, Blockchain, Next.js, React, TypeScript, Decentralized Finance (DeFi), Non-fungible Tokens (NFT), DApps, Fintech, Security Audits, Fuzz Testing

The most amazing...

...thing I've built is one of the first fee-less blockchains in 2018 and non-custodial libraries and protocols for fields, such as DeFi, gaming, and gambling.

Work Experience

Chief Technical Officer

2018 - PRESENT

Progressive Web Apps

Developed back-end and front-end solutions for clients that required KYC and AML expertise. I developed the back end in Node.js and the front end in React.
Built ERC20 tokens, ERC677 tokens for multiple clients, and ICO campaigns with multistage vesting emissions. In the past year, we focused on building DAOs and voting systems in which proposers, voters, and executers maintain the community treasury.
Helped a few local artists launch their independent and ERC721 NFT collections. A few of the NFTs provided access to a private website section that allowed only private members to join.
Built multiple projects that used ERC721 and ERC1155 to incentivize a private community focused on DAO governance.
Developed solutions that revolved around Chainlink and APIs to ensure on-chain whitelisting and revalidation for existing members.
Integrated Chainlink Price Feeds into multiple ICOs to provide full conversion in USD for every major supported cryptocurrency. This ensured strict USD limits that were compliant with KYC and AML rules.
Contributed to the Loom Network interoperable bridges and universal wallets.
Integrated more than 30 non-custodial wallets inside front ends.

Technologies: Blockchain, Cryptocurrency, Non-fungible Tokens (NFT), ICO, Sidechains, JavaScript, Smart Contracts, Web3.js, Ethereum Smart Contracts, ERC-721, Decentralized Applications, Node.js, Fintech, Decentralized Finance (DeFi), JSON-RPC, Cryptocurrency Wallets, Blockchain & Cryptocurrency, Ethers.js, Blockchain Design, MetaMask, HTML, CSS, TypeScript, Full-stack, Security, Architecture, Banking & Finance, Express.js, IT Security, IPFS, API Architecture, Blockchain Platforms, Blockchain Game Development, Next.js, Distributed Systems, Vercel, Audits, Ethereum, Team Management, Scrum, Agile, Scrum Master, Team Leadership, Agile Project Management, Project Management, APIs, IT Infrastructure, Solidity, Crypto, Software, Arbitrage, Decentralization, Flash Loans, Decentralized Exchanges (DEXs), Integration, API Integration, Go, Decentralized Systems, Software Architecture, Amazon Web Services (AWS), Microservices, Bots, Trading, Tokenization, Quality Assurance (QA), QA Automation, QA Leadership, QA Testing, Manual QA, Utility Tokens, Technical Leadership, Technical Requirements, Estimations, Web 3.0, GitHub, ERC-1155, ERC-20, Twilio, Healthcare Services, React, RPC, WebSockets, P2P, Advisory, Project Consultancy, DApps, MySQL, Python, Web Development, Algorithms, Software Engineering, Front-end, WebAssembly, Webhooks, Stock Exchange, CTO, Leadership, Digital Asset Management, Fractionalization, DigitalOcean, Cryptocurrency Exchanges, NoSQL, Back-end Development, Blockchain as a Service, Jira, Parsers, Fuzz Testing, Compilers, Web3, Casinos & Gaming, Gambling, Tailwind CSS, Public Finance, Back-end, Sequelize, Product Growth, SQL, Oracle, Foundry, Web Scraping, API Development, GraphQL, Push Notifications, Biomedical Skills, Token Design, Databases, HTML5, Ledgers, Off-chain Development, Troubleshooting, Auditing, Binance API, GRAPH, ÐApp, Marketplaces, MultiChain, Kubernetes, Vue, CI/CD Pipelines, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Microservices Architecture, Applied Cryptography, Test Scripting, token airdrop, Distributed Ledger Technology (DLT), Avalanche, White Papers, Computer Science, Cryptography, Cybersecurity, Geth (go-ethereum), Technical Writing, Distributed Computing, Apps, Quantitative Finance, Linux, Etherscan

Chief Technology Officer, Blockchain

2023 - 2023

Psalm, LLC (dba Psalm DAO)

Reduced ERC721 smart contract IT costs to around 13 MATIC on Polygon to mint 20,000 NFTs.
Lowered gas fees to around 0.0005 MATIC for the same batch of 20,000 NFTs after upgrading the codebase to ERC721A.
Helped configure and deploy Next.js and Vercel for the website.
Managed two teams and mentored developers on using the Ethereum virtual machine (EVM) to help them use newer EVM tricks more efficiently to reduce gas costs.

Technologies: Blockchain, Smart Contracts, CTO, Non-fungible Tokens (NFT), Cryptocurrency, DigitalOcean, Security, Oracle, Token Design, Data Queries, Redis, HTML5, Troubleshooting, ÐApp, CI/CD Pipelines, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Microservices Architecture, Architecture, Applied Cryptography, Distributed Ledger Technology (DLT), White Papers, Computer Science, Cryptography, Cybersecurity, Geth (go-ethereum), Etherscan

Blockchain Expert

2023 - 2023

Opus Momentus Proprietary Limited

Built a fully functional cross-chain hedge with six core features: wallet creation, staking, deposits, relayer, aggregator, and withdrawal.
Created the back end and fault tolerance using two mirror databases: relational and non-relational.
Developed deposit tracking using Alchemy SDK and deposits aggregator contracts deployed on each chain.

Technologies: Blockchain, Tokenomics, Cryptocurrency Wallets, Product Growth, SQL, Oracle, API Development, Token Design, Databases, PostgreSQL, HTML5, Ledgers, Off-chain Development, Troubleshooting, Auditing, ÐApp, MultiChain, Kubernetes, CI/CD Pipelines, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Microservices Architecture, Architecture, Applied Cryptography, Test Scripting, Distributed Ledger Technology (DLT), White Papers, Computer Science, Cryptography, Cybersecurity, Geth (go-ethereum), Apps, Linux, Etherscan

Blockchain Expert

2023 - 2023

Hoichi

Developed a Solidity smart contract for Hoichi DAO to distribute prizes incurred from the Hoichi Token Uniswap buy and sell fees to their 369 ERC-721 NFT holders.
Built the raffle to support the Chainlink VRF self-subscription method.
Tested on Sepolia, simulated on Mainnet, and created the deployment configuration.
Deployed the raffle to Ethereum Mainnet successfully.
Passed all audits with flying colors—no issues found.

Technologies: Blockchain, Chainlink, Smart Contracts, Solidity, Parsers, Fuzz Testing, Compilers, Web3, Casinos & Gaming, Public Finance, Back-end, Oracle, Foundry, HTML5, Troubleshooting, Auditing, ÐApp, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Microservices Architecture, Architecture, Applied Cryptography, Distributed Ledger Technology (DLT), Computer Science, Cryptography, Etherscan

Blockchain Lead

2022 - 2022

Freelance Client

Discovered multiple critical vulnerabilities and logic flaws in multiple projects that the team was working on and helped protect and migrate liquidity to safe versions.
Created a thorough security report detailing the problems discovered and mitigation steps with scenario outcome recommendations.
Rewrote the v1 codebase into the most gas-efficient version with native MEV Protection.
Innovated trading protection features and OTC Token sales. Led auditing, testing, deployments, and liquidity migrations that covered all edge cases and successfully migrated all vulnerable liquidity using flashbots and shielded transactions.
Added protected transactions to prevent MEV bots from executing a sandwich attack on users by draining their slippage tolerance.
Added a check that enforces multi-transfers only to be done once per block by each user when transferring and thus prevented MEV bots from making arbitrage and transaction reordering plays.
Performed a lot of planning, rewrites, dead code, and improved gas costs to the latest versions with no technical debt.
Made a snapshot of balances for V1 and minted an equal amount in V2 contracts.
Helped coordinate with team members and assisted them in creating local forks and Gnosis treasury proposals, votes, and quorum executions via Flashbots.
Trained three developers on how to do mainnet fork and simulations. Created scripts to extract liquidity and do the migrations successfully.

Technologies: Blockchain, Solidity, Team Management, Scrum, Agile, Scrum Master, Web3.js, Team Leadership, Agile Project Management, Project Management, Integration, API Integration, Memory Pools, Decentralized Systems, Software Architecture, REST APIs, Microservices, Bots, Tokenization, Quality Assurance (QA), QA Automation, QA Leadership, QA Testing, Manual QA, Utility Tokens, Technical Leadership, Technical Requirements, Estimations, Web 3.0, GitHub, ERC-20, Twilio, React, Next.js, JavaScript, Full-stack, RPC, WebSockets, P2P, Advisory, Project Consultancy, Go, DApps, Audits, Ethereum, Web Development, Algorithms, Software Engineering, Front-end, Webhooks, Stock Exchange, CTO, Leadership, Digital Asset Management, Exchanges, Fractionalization, NoSQL, Back-end Development, Jira, Parsers, Fuzz Testing, Compilers, Web3, Casinos & Gaming, Gambling, Tailwind CSS, Public Finance, Back-end, Product Growth, Oracle, API Development, Token Design, HTML5, Troubleshooting, Auditing, GRAPH, ÐApp, Scripting, Full-stack Development, Microservices Architecture, Applied Cryptography, Test Scripting, Distributed Ledger Technology (DLT), Computer Science, Cryptography, Cybersecurity, Linux, Etherscan

Expert Smart-contract Blockchain Developer

2022 - 2022

Freelance Clients

Created MultiCall contracts, tests, and protected transactions.
Handled Alchemy scripts and Flashloans private transactions relayed to the Flashbots bundlers to minimize MEV Bots from reading the transactions in the memory pool and doing frontrunning, sandwich attacks, arbitrage, and flash loans.
Built forks, setups, tests, and local fork simulations.

Technologies: Solidity, Blockchain, Smart Contracts, Decentralized Finance (DeFi), Integration, API Integration, Memory Pools, Software Architecture, Microservices, QA Testing, Manual QA, Utility Tokens, Estimations, Web 3.0, GitHub, ERC-20, Twilio, React, Next.js, Web3.js, Full-stack, RPC, WebSockets, P2P, Advisory, Project Consultancy, DApps, Audits, Ethereum, Web Development, Algorithms, Software Engineering, Front-end, Webhooks, Leadership, Digital Asset Management, Exchanges, Fractionalization, NoSQL, Back-end Development, Parsers, Fuzz Testing, Compilers, Web3, Tailwind CSS, Fantom, Public Finance, Back-end, Oracle, API Development, HTML5, Troubleshooting, Binance API, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Microservices Architecture, Applied Cryptography, Test Scripting, Distributed Ledger Technology (DLT), Computer Science, Cryptography, Cybersecurity, Quantitative Finance, Etherscan

Senior Full-stack Developer

2018 - 2018

Fii pe net

Trained five junior colleagues, which allowed us to reduce deployment times and increase productivity.
Built and maintained a big data real estate data scraper that made cross-referenced filters for the LIFA Denmark API using TypeScript.
Developed numerous WordPress websites and maintained their security.
Handled SEO growth hacks and ensured our audit coverage was always up to date.

Technologies: Websites, React, WordPress, Design, APIs, JavaScript, Web3.js, Ethereum Smart Contracts, Node.js, JSON-RPC, Blockchain Design, MetaMask, HTML, CSS, TypeScript, Full-stack, DevOps, Express.js, IT Security, API Architecture, Blockchain Platforms, Blockchain Game Development, Distributed Systems, Team Management, Scrum, Agile, Team Leadership, Agile Project Management, Project Management, Chainlink, Cryptocurrency Wallets, Infrastructure, IT Infrastructure, Solidity, Crypto, Software, ERC-20, Smart Contracts, Amazon Web Services (AWS), Integration, API Integration, Software Architecture, REST APIs, Microservices, Bots, Trading, QA Automation, QA Testing, Web 3.0, Netlify, GitHub, Healthcare Services, RPC, WebSockets, VPN, P2P, Project Consultancy, Networks, Go, DApps, Audits, Blockchain, MySQL, Web Development, Algorithms, Software Engineering, Front-end, Webhooks, NoSQL, Back-end Development, Parsers, Compilers, Web3, Public Finance, Back-end, Web Scraping, API Development, Push Notifications, Databases, PostgreSQL, Data Queries, Redis, HTML5, Troubleshooting, ÐApp, Scripting, Full-stack Development, Microservices Architecture, Applied Cryptography, Truffle, Test Scripting, Computer Science, Cryptography, Geth (go-ethereum), Linux

API Developer

2015 - 2017

AWC LLC

Developed the front end and integrated wallets using BitGo APIs that enabled crypto payments within the platform.
Started an experiment that turned into a non-custodial wallet by building a PIN-password lock/unlock feature that allowed discovery and self-recovery of the private key using the Curve25519-based algorithm.
Built the API that handled the Magento and Shopify plugins and open-source plugins used by developers to handle big data processing for payment solutions.
Owned full responsibility for development environments and product deployments.

Technologies: Blockchain, Payment APIs, Ethereum, Bitcoin, JavaScript, Smart Contracts, Web3.js, Ethereum Smart Contracts, Node.js, Fintech, JSON-RPC, Ethers.js, Blockchain Design, MetaMask, HTML, CSS, Full-stack, DevOps, Banking & Finance, Express.js, IT Security, API Architecture, Blockchain Platforms, Distributed Systems, Scrum, Agile, Scrum Master, Team Leadership, Agile Project Management, Project Management, APIs, Chainlink, Cryptocurrency Wallets, IT Infrastructure, Solidity, Crypto, Software, Decentralization, Integration, API Integration, Go, Software Architecture, REST APIs, Amazon Web Services (AWS), QA Automation, Utility Tokens, Netlify, GitHub, Healthcare Services, RPC, WebSockets, TypeScript, VPN, P2P, Advisory, Project Consultancy, Networks, DApps, MySQL, Python, Web Development, Algorithms, Software Engineering, Front-end, NoSQL, Back-end Development, Parsers, Compilers, Web3, Public Finance, Back-end, API Development, Databases, PostgreSQL, Data Queries, Redis, HTML5, Troubleshooting, Scripting, Full-stack Development, Microservices Architecture, Applied Cryptography, Test Scripting, Computer Science, Cryptography, Cybersecurity, Geth (go-ethereum), Linux

iOS App Developer

2014 - 2015

iSecurity LLC

Built an app using Objective-C with video, audio streaming, and access to CCTV cameras that displays employee schedules and tracks and audits schedules.
Managed multiple clones of the same app for different clients, increasing management and productivity while making time-consuming tasks easy to perform.
Took responsibility for auditing every update before publishing.
Helped developers ship faster by maintaining environments and ensuring tight security.

Technologies: Objective-C, iOS, MongoDB, Security, Architecture, DevOps, IT Security, Cryptocurrency Wallets, IT Infrastructure, Solidity, Crypto, Software, Integration, API Integration, Software Architecture, Trading, GitHub, Networks, Algorithms, Software Engineering, Front-end, Parsers, Compilers, Web Scraping, API Development, Databases, PostgreSQL, HTML5, Troubleshooting, Full-stack Development, Applied Cryptography, Computer Science, Cryptography, Apps, Linux

Experience

Bitcoin Lottery

https://demo.btclottery.io

This project has been my biggest hobby and self-imposed "impossible" challenge for the past seven years. I pushed myself beyond standards and my own experience to explore what works and what doesn't. Initially, I set out to build unstoppable randomizing distribution mechanisms in a raffle-style game on top of Bitcoin. I learned the hard way that Bitcoin smart contracts back then were not Turing-complete and did not support a lot of programming features.

In 2016, I ended up with a centralized version due to my lack of knowledge. The original version, which I didn't like, was never made public. Bitcoin was $250 at that time. As years passed, new blockchain technologies constantly rechallenged me to rethink and rebuild. I joined the sidechain hype in its early days in 2017 and set out to improve speed and eliminate costs for permissionless environments. These environments couldn't be spammed and could be feeless while always allowing creators to create their own token distribution mechanisms that automatically rewarded their userbases with the help of Chainlink VRF and Chainlink Keepers. The current version uses a DPOS model with a maximum of 21 modes, similar to the Binance Smart Chain.

Randomizer Network

https://randomizer.network

The Randomizer Network is a novel deflationary Launchpad Protocol backed by Chainlink Verifiable Random Function (VRF) and Chainlink Keepers to ensure that all the Meta Pass Holders automatically participate in the daily deflationary no loss lottery.

Store Payment Processor

https://sfpy.co

Built a self-custodial payment processor that clients and merchants can use in a wallet-to-wallet fashion. Clients can switch between client and merchant mode and create their invoices, share them, and get paid directly in their wallets using cryptocurrencies on Ethereum and Polygon Network.

Joystick Gaming

https://joystickgaming.io/

Joystick is bridging the gap between Web2 and Web3 where people can earn money in the video game industry by playing games, streaming, and creating content.

I did a security audit and discovered a critical vulnerability and helped save and migrate their existing liquidity that was vulnerable and went unnoticed by multiple top auditors. Additionally, I rewrote the Joy Token and xJoy Token, added on-chain MEV protection, created the Presale contract with a live AMM OTC sale which sends xJoy to the user, and created a Claim Page using React + Next.js + Typescript in which users could see all their calculations for the 8 months cliff + 3 years linear vesting releases of the OTC.

Finally, I helped their team become better and more efficient by learning how to fork Ethereum Mainnet.

Dough Finance

The Dough Finance Dapp is a DeFi non-custodial bank that has pioneered a new feature using flash loans, which simplifies users' possibilities to overcollaterize their positions by three times in a single transaction and leverages the money multiplier effect in a single transaction called loop and deloop.

Skillset

Languages

Solidity, JavaScript, HTML, CSS, TypeScript, Fantom, SQL, HTML5, Go, Objective-C, C, C++, Assembly, Python, GraphQL, Solidity Assembly

Frameworks

Next.js, Hardhat, Express.js, Tailwind CSS, Truffle

Libraries/APIs

React, Node.js, Web3.js, JSON-RPC, REST APIs, API Development, Vue, Binance API

Tools

MetaMask, GitHub, VPN, Jira, Etherscan, Sequelize, Geth (go-ethereum)

Paradigms

DevOps, API Architecture, Microservices, Fuzz Testing, Microservices Architecture, Distributed Computing, Scrum, Agile, Agile Project Management, Interoperability

Platforms

Blockchain, Ethereum, Chainlink, Blockchain Platforms, Amazon Web Services (AWS), Twilio, DigitalOcean, Oracle, MultiChain, Kubernetes, Linux, Vercel, Netlify, iOS, WordPress

Storage

NoSQL, Databases, PostgreSQL, Redis, MongoDB, MySQL

Industry Expertise

Cybersecurity, Banking & Finance, Project Management

Other

BNB Smart Chain, Tokenomics, Quality Assurance (QA), Non-fungible Tokens (NFT), Payment APIs, APIs, Cryptocurrency, ICO, ERC677, Smart Contracts, Ethereum Smart Contracts, ERC-721, Decentralized Applications, Fintech, Decentralized Finance (DeFi), Cryptocurrency Wallets, Blockchain & Cryptocurrency, Ethers.js, Blockchain Design, Decentralized Autonomous Organizations (DAO), DApps, Full-stack, Security, Architecture, ERC-1155, Audits, Team Leadership, Infrastructure, IT Infrastructure, Crypto, Software, Decentralization, Flash Loans, Decentralized Exchanges (DEXs), Integration, API Integration, Decentralized Systems, Software Architecture, Consensus Mechanism, Tokenization, QA Automation, QA Leadership, QA Testing, Manual QA, Utility Tokens, Technical Leadership, Technical Requirements, Estimations, Web 3.0, ERC-20, RPC, WebSockets, P2P, Advisory, Project Consultancy, Networks, Web Development, Algorithms, Software Engineering, Front-end, Webhooks, Stock Exchange, CTO, Leadership, Digital Asset Management, Exchanges, Fractionalization, Cryptocurrency Exchanges, Admin Panels, Back-end Development, Blockchain as a Service, Parsers, Compilers, Web3, Casinos & Gaming, Gambling, Public Finance, Back-end, Product Growth, Foundry, Web Scraping, Push Notifications, Token Design, Data Queries, Ledgers, Off-chain Development, Troubleshooting, Auditing, ÐApp, Marketplaces, CI/CD Pipelines, Scripting, Ethereum Virtual Machine (EVM), Full-stack Development, Applied Cryptography, Test Scripting, token airdrop, Distributed Ledger Technology (DLT), White Papers, Computer Science, Cryptography, Technical Writing, Apps, Quantitative Finance, Economics, Finance, Bitcoin, Websites, Games, IT Security, IPFS, Blockchain Game Development, Distributed Systems, Team Management, Scrum Master, Polygon, Memory Pools, Bots, Trading, Healthcare Services, WebAssembly, Biomedical Skills, Avalanche, Sidechains, Design, Universal Wallet, Blocknative, Arbitrage, Lottery, Security Audits, GRAPH, iOS Games, Smart Contract Auditing

Education

2016 - 2019

Bachelor's Degree in Economics

Universitatea Tomis - Constanta, Romania

2014 - 2016

Bachelor's Degree in Computer Science

Universitatea Ovidiu - Constanța, Romania

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.

Share your needs

Discuss your requirements and refine your scope in a call with a Toptal domain expert.

Choose your talent

Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.

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