Gregory Roussac

Freelance software engineer focused on Rust backend systems, distributed architectures, SDK development and blockchain infrastructure. Recent engagements include Casper Labs, Casper Association and confidential enterprise platforms under NDA.

• Enterprise Systems
  • High-performance Rust backend systems for APIs, microservices, transaction processing using Actix and Axum (REST APIs), SeaORM, Straddle, and AWS SQS/S3 event-driven Rust workers
  • Multi-service Docker Compose environments, pre-production infrastructure, and Nx monorepo integration (Angular, NestJS)
• Backend Systems & Distributed Architecture
  • PostgreSQL backends (SQLx, SeaORM) with event-driven architectures and AWS SQS messaging
  • Design and maintenance of Docker-based distributed environments (multi-service stacks, LocalStack, CI parity, networking)
  • AWS deployments with CI/CD pipelines (GitHub Actions)
  • WASM tooling and browser/runtime Rust applications (wasm-bindgen)
• Blockchain / Cryptographic Infrastructure & Ecosystem Engineering
  • Rust smart contract upgrades and Casper 2.0 migration work for Casper Association
  • KMS Secp256k1 API (github.com/gRoussac/kms-secp256k1-api)
    Rust custodial wallet middleware on AWS backed secp256k1 key lifecycle and transaction signing for Ethereum, Casper, and Cosmos
  • WASM runtime cryptographic layer (wasmtime), IAM-scoped role permissions, and secure signing workflows
• Selected Open Source & Research Projects
  • Smart contract development across Rust and Solidity ecosystems (Ethereum, Casper, Solana, Hedera)
  • AquaChain (EU-funded, India): CosmWasm smart contracts using Sylvia
  • Solana Anchor prototype: on-chain AI agent registry smart contract

Frontend engineer at a large Dutch comparison platform for insurance, energy, mortgage, and financial products, working across multiple high-traffic customer-facing applications.

• Led AngularJS to Angular migrations across customer-facing applications
• Mortgage (hypotheek) domain: developed complex comparison flows and a conversational mortgage advisory chatbot for the Dutch market
• Delivered frontend features across insurance, automotive, and financial product verticals (health insurance, car insurance, etc.)
• Built and maintained standalone frontend widgets using Preact, Vue.js, and native JavaScript outside of the main Angular stack
• Implemented strong automated testing and delivery pipelines using Jest, Cypress, and CI/CD workflows

Backend and platform engineer working on Magento hosting infrastructure (Hypernode), customer tooling, and security-focused analysis of large-scale merchant ecosystems.

• React and TypeScript development on Hypernode customer backend platform
• Built asynchronous Python pipelines to analyse and process large-scale merchant site datasets (Magereport / Hypernode ecosystem)
• Developed headless browser analysis tooling (Puppeteer, PhantomJS) to inspect and deobfuscate client-side JavaScript for security and integrity checks
• Created the open-source "Evaluator" project, including a deobfuscation API and Rust-based CLI for parallelised merchant scanning and evaluation
• Conducted large-scale analysis of compromised merchant websites (credit-card skimming / script injection detection), identifying ~1,800 affected sites. Worked across Python, Node.js, and DevOps tooling on hosting infrastructure (Hypernode, Magento, Linux)

Founded and managed a PrestaShop and WordPress agency (Silver Partner), delivering e-commerce development, integrations, and training services. Full responsibility for business operations, client acquisition, delivery, and team management (~€250K annual revenue, employees and interns). Also PrestaShop Trainer | Sep 2011 – Aug 2012, e-Commerce Academy, Paris, FR

• Led end-to-end agency operations including sales, client management, subcontractors, hiring, and delivery oversight
• Delivered PHP / MySQL development, PrestaShop and WordPress implementations, and merchant integrations for production e-commerce sites. Delivered PrestaShop developer and theme training covering modules, frontend customization, template systems and UI integration

Core contributor to an early-stage open-source e-commerce platform, working on core product development and merchant implementations across multiple production deployments.

• PHP / MySQL / JavaScript development and XHTML integration on PrestaShop Core platform
• Merchant implementations and production rollouts for early adopters (e.g., smallable.com, labagagerie.com, 4-pieds.com)
• Developed payment modules (Atos, Paybox, Cybermut), logistics integrations (Crosslog), and product feed exports prior to the Addons marketplace. Coordinated outsourced theme and integration projects supporting early commercial services

Backend developer and project contributor at a Paris-based email marketing company specializing in large-scale campaigns.

• Developed PHP/MySQL applications and web services for large-scale email marketing platforms and client integrations

Founder and technical operator of an online wine retail business, responsible for end-to-end technical systems and logistics operations.

• Designed, developed, and launched the e-commerce platform using PHP/MySQL/JavaScript
• Built internal back-office systems (VB + MySQL) for orders, inventory, customer and operations management
• Managed end-to-end business operations including warehousing, customs, logistics, and supplier contracts

Web agency working on Streamplug, a video streaming platform and web tooling solution.

• Developed PHP/MySQL backend features and JavaScript/XHTML frontends for web applications and early video streaming web components