Senior Software Lead

Sacha Simoens Senior Software & Blockchain Engineer

***.*********@*****.*** Wemmel, Flemish Region, Belgium linkedin.com/in/sacha-simoens-760740150 Profile

Software & Blockchain Engineer specialized in Solidity smart contract development, DeFi integrations, and cross-chain interoperability. Skilled in secure protocol design, gas optimization, and audit-ready testing (unit, integration, fuzz, invariant). Experienced in web3 full-stack development with React, Node.js, and ethers.js, and proficient in building DevOps pipelines and AI-assisted security workflows to deliver scalable, production-grade blockchain solutions.

Professional Experience

Lead Software & Blockchain Engineer

CBTW

03/2024 – 01/2025

•Architected and deployed Solidity-based protocols handling tokenized assets, DAO governance modules, staking pools, and treasury vaults, securing millions in TVL across Ethereum and Polygon.

•Implemented ERC-20, ERC-721, and ERC-4626 contracts, incorporating upgradeable proxy patterns

(Transparent/UUPS) to ensure long-term maintainability and backward compatibility.

•Built DeFi integration adapters (Uniswap v3 swaps, Aave lending/borrowing, Compound yield farming), allowing treasury and client applications to directly interact with existing DeFi liquidity.

•Designed modular governance contracts supporting proposals, time-locked execution, delegated voting, and quorum thresholds with off-chain Snapshot integration.

•Applied advanced gas optimization techniques: inline Yul assembly for hashing and signature validation, calldata packing/unpacking for batch swaps, memory slot reuse, reducing transaction costs by ~30%.

•Developed multi-chain bridging contracts with LayerZero/Axelar, supporting ERC-20 and NFT transfers across EVM chains; validated bridge logic with invariant testing and adversarial fuzz simulations.

•Wrote comprehensive test coverage (Hardhat + Foundry): unit tests, integration tests on forked mainnet state, fuzz/invariant tests for slippage, oracle manipulation, and collateral safety.

•Integrated AI-driven security analyzers into CI/CD pipelines to detect delegatecall hazards, storage slot collisions, and gas inefficiencies before deployment.

•Partnered with auditors (Quantstamp, Trail of Bits) to resolve findings, eliminating reentrancy vectors and access control bypasses.

•Built React/Next.js dashboards for staking, treasury monitoring, governance voting, and on-chain analytics, powered by The Graph for subgraph indexing.

Lead Software & Blockchain Engineer

Positive Thinking Company

09/2020 – 03/2024

•Designed and deployed Solidity smart contracts for Layer 2 scaling solutions: rollup contracts, fraud-proof verifiers, and challenge-response game mechanics.

•Implemented staking + liquidity mining contracts with flexible emission curves, time-locked rewards, vesting, slashing penalties, and DAO-governed parameters.

•Built cross-chain bridge adapters between Ethereum, Polygon, and Binance Smart Chain (BSC) for asset transfers; ensured security with dual-signature oracles + Merkle proofs.

•Engineered DEX liquidity pool contracts with dynamic fee models, TWAP-based price oracles, and MEV-resilient swap functions.

•Applied formal verification + fuzz testing (Echidna, Foundry invariants) to validate lending pool solvency, collateralization ratios, and governance quorum safety.

•Delivered gas-optimized staking logic by restructuring storage layouts, consolidating mappings, and using unchecked arithmetic when safe, achieving up to 25% savings.

•Built The Graph subgraphs indexing liquidity events, staking rewards, and governance votes; exposed metrics via APIs for React/TypeScript dApps.

•Developed upgradeable proxy architecture (EIP-1967 + UUPS) across all major contracts, enabling feature iteration while preserving contract state.

•Integrated AI-powered transaction anomaly detection into monitoring stack: flagged abnormal withdrawal spikes, governance attack attempts, and flash-loan manipulations in near real-time.

•Mentored teams of 5–7 engineers on Solidity design patterns, reentrancy-safe architectures, gas profiling workflows, and modular contract development.

Blockchain Engineer

Blue Chaingers

05/2019 – 02/2022

•Built and deployed smart contracts for digital identity + KYC systems, ensuring verifiable credentials anchored on Ethereum and compatible with enterprise APIs.

•Developed Solidity payment channel contracts to reduce transaction costs for micro-payments, with dispute resolution + state channel mechanics.

•Implemented Golang-based blockchain nodes and C++ crypto modules to extend custom consensus layers for internal PoA network.

•Integrated oracle services (Chainlink + custom API bridges) to feed real-time financial data into DeFi products.

•Created extensive testing suites with Hardhat + Mocha: unit, integration, fuzz testing for state channels and signature validation.

•Designed React dashboards for real-time payment status + audit trails, integrated with WalletConnect. Software Developer

ADNEOM

01/2019 – 09/2020

•Designed and developed Node.js microservices for fintech and enterprise clients, handling high-throughput transaction flows, authentication, and digital signing pipelines.

•Prototyped Solidity ERC-20 and ERC-721 token contracts for client proof-of-concepts, including minting logic, access control, and role-based permissions.

•Built smart contract interaction layers in Node.js + web3.js, enabling backend services to execute token transfers, query balances, and trigger events on Ethereum testnets.

•Set up Dockerized development environments with CI/CD (GitLab CI, Jenkins), automating smart contract deployments, ABI generation, and integration testing against Ganache/Ethereum testnets.

•Applied unit and integration testing with Hardhat + Mocha, validating token economics, event emissions, and access control failures.

•Collaborated with client security teams to implement audit-prep workflows: static analysis with Slither, linting rules, and coding standards aligned with OpenZeppelin libraries.

•Contributed to DevOps pipelines for blockchain-based prototypes, deploying containerized full-stack applications with monitoring and logging integrations. Software Developer

Big Smile Agency

08/2017 – 10/2018

•Built web applications in PHP and Node.js with custom APIs for digital marketing and creative clients, handling campaign data, analytics, and user management.

•Developed early Solidity smart contract prototypes for NFT-like digital ownership proofs, enabling creative agencies to tokenize artwork and track transfers.

•Implemented REST and GraphQL APIs for dApp frontends to interact with Ethereum testnet contracts via MetaMask and web3.js.

•Created React.js dashboards to visualize contract data (minted tokens, ownership transfers, transaction history).

•Set up automated test suites for full-stack applications, including smart contract interaction tests to ensure ERC- 721 compliance and error handling.

•Contributed to multi-environment deployments (local/testnet/mainnet staging) with Docker and CI/CD, ensuring reproducible builds and reliable contract deployments.

•Documented best practices for web3 integrations, preparing internal guides on wallet connection, gas estimation, and handling contract reverts in UI workflows. Education

Bachelor's degree of Computer Science

Université libre de Bruxelles (ULB)

2013 – 2015

Skills

Blockchain & Smart Contracts

Solidity, Rust (Solana/Substrate), CosmWasm, Golang, EVM (Ethereum, Polygon, Arbitrum, Optimism),

LayerZero, Axelar, Uniswap/Aave/Compound

integrations

Full-stack & Web3 Development

React, Next.js, Node.js, TypeScript, Python, ethers.js, web3.js, viem, wagmi, WalletConnect, GraphQL, The

Graph

AI & Data Engineering

AI-powered code analyzers, ML models for

fraud/anomaly detection on-chain, AI-assisted security review workflows, predictive analytics

Smart Contract Security & Testing

Hardhat, Foundry, Brownie, Truffle, Slither, Echidna, Mythril, Manticore, invariant & fuzz testing, gas

profiling, reentrancy protections

Systems & DevOps

Docker, Kubernetes, CI/CD (GitHub Actions, Jenkins, GitLab CI), Terraform, Prometheus, Grafana,

logging/monitoring pipelines

Languages & General Software

C++, Java, PHP, NestJS, PostgreSQL, MongoDB, Redis

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