Sylvain is available for hire
Hire SylvainSylvain Vittecoq
Verified Expert in Engineering
Software Developer
Stockholm, Sweden
Toptal member since August 17, 2022
Bio
Sylvain's been a CTO, engineering manager, and senior software engineer in the US and Europe. He is a very hands-on, result-oriented expert in Java and solution definition and can work with anyone from engineers to C-level execs. Sylvain's delivered nationwide security infrastructures for millions of devices and connected millions of eCommerce users. Sylvain founded FileChain to offer next-generation blockchain platforms for large-scale Web 3.0, Industry 4.0, and NFT decentralized marketplaces.
Portfolio
Santiago Aceves
Blockchain, Solana, Smart Contracts, Cryptocurrency, Tokenization...
Media
Software Architecture, General Ledgers, Database Design, Shopify...
FileChain
Java, Blockchain, Decentralized Systems, Non-fungible Tokens (NFT), Web 3.0...
Experience
- Java - 20 years
- Back-end - 18 years
- Architecture - 13 years
- Leadership - 12 years
- CTO - 10 years
- SQL - 10 years
- Blockchain - 8 years
- Spring - 3 years
Preferred Environment
Linux, Eclipse IDE, Open Source, Git, Java
The most amazing...
...implementation I've done was a next-gen enterprise ledger with end-to-end privacy, in-chain storage, thousands of transactions per second, and 100% Java-based.
Work Experience
Blockchain Expert
2025 - PRESENT
Santiago Aceves
- Proposed a full architecture/solution for business-critical and legally binding asset transfers in the real estate industry between many US-based companies and agencies using the FileChain (Filechain.com/ledger technology).
- Architected the zero-knowledge platform for all parties to share documents and forms over a decentralized permissioned ledger to enable an enterprise-grade transactional platform.
- Developed a set of APIs and REST endpoints for a fully functional Java-based standalone solution using the FileChain SDK.
Technologies: Blockchain, Solana, Smart Contracts, Cryptocurrency, Tokenization, Project Discovery, Ethereum, Cardano, Project Management, Project Budget Management, Real Estate, Technical Project Management, Web Scalability, Agentic AI
Principal Engineer
2022 - PRESENT
Media
- Provided a complete Web3 marketplace with NFTs and a coin as a unit of payment using the FileChain enterprise-grade ledgers and treasuries.
- Designed the overall solution architecture and platform for selling, buying, and managing inventory on this marketplace.
- Acted as technical lead defining time plans, cost estimates, and work packages with other parties or suppliers, including FileChain and Shopify.
Technologies: Software Architecture, General Ledgers, Database Design, Shopify, Progressive Web Applications (PWAs), Advisory, JavaScript, Non-fungible Tokens (NFT), Blockchain, FileChain, Digital Asset Management, End-to-end Privacy, Technical Project Management, Web Scalability
Founder and Lead Developer
2016 - PRESENT
FileChain
- Implemented fully featured next-generation ledgers; used 100% Java, 400,000 lines of code, and is fully NIST compliant.
- Promoted enterprise ledger platforms and full SDK to blockchain clusters and developer communities in many industries, including supply-chain, DEFI, social marketing, and so on.
- Delivered multiple decentralized marketplaces with end-to-end privacy, full identity management, contract management, fungible coins, and NFTs.
- Oversaw sales activities and managed business developers and seed investment in December 2019.
- Wrote two patent applications for high-performance and low operational cost software designs for decentralized ledger platforms.
Technologies: Java, Blockchain, Decentralized Systems, Non-fungible Tokens (NFT), Web 3.0, Industry 4.0, Business to Business (B2B), Linux, Eclipse IDE, Open Source, Performance Tuning, Architecture, Team Building, Strategy, Startups, Databases, User Interface (UI), Team Management, Large-scale Distributed Systems, Software, Design, Planning, Storage, Large Data Sets, Performance, REST, Git, File Systems, CSS, HTML5, JavaScript, SQL, Service-oriented Architecture (SOA), PostgreSQL, MongoDB, HTML, Spring, Spring Boot, Leadership, APIs, Software Design, Serverless, System Architecture, Requirements Analysis, Requirements, REST APIs, Software Development Lifecycle (SDLC), Software Development Toolkits (SDK), Windows PowerShell, Technical Product Management, CTO, IT Strategy, Back-end, Big Data, Data Processing, Low Latency, Multithreading, Oracle, Microservices, SSL, Java EE (Jakarta EE), Docker, TypeScript, Terraform, Full-stack, Web Development, React, Blockchain Platforms, Blockchain Design, Smart Contracts, Decentralized Autonomous Organizations (DAO), Ethereum, Solidity, Blockchain & Cryptocurrency, Decentralized Exchanges (DEXs), ERC-20, Team Leadership, Management, Teamwork, Cross-functional Team Leadership, Solution Architecture, Distributed Ledgers, Distributed Architecture, Decentralized Finance (DeFi), Decentralized Applications, Integration, API Integration, Ethereum Smart Contracts, Crypto, Jira, GitHub, CSS Grid, Bitcoin, Cryptocurrency, Applied Cryptography, Governance, Full-stack Development, Digital Banking, Central Bank Digital Currency (CBDC), GraphQL, Rust, gRPC, Redis, Technical Leadership, Azure, Project Management, Software Architecture, Java 11, Trading Systems, Cryptography, API Development, Key Performance Indicators (KPIs), Fintech, Node.js, Scalable Application, Scalable Architecture, Cryptocurrency APIs, Filecoin, Web3, Algorithms, Early-stage Startups, Privacy, Data Privacy, Social Networks, Agile Delivery, B2B, Engineering, Product Growth, Banking & Finance, Web3.js, Digital Asset Management, Hyperledger, End-to-end Privacy, Engineering Management, Technical Project Management, Industry 4.0, Data Strategy
Blockchain Engineer
2024 - 2025
Quranium Global DMCC
- Helped define the overall architecture for this post-quantum layer 1 public blockchain based on Ethereum.
- Managed a team of talented software engineers and testers to deliver on time and within budget, and publicly launch one of the very first post-quantum public layer 1 blockchains.
- Led the integration of partners to run validator nodes and helped define the overall tokenomics post-launch.
Technologies: Blockchain, C++, Cryptography, Bitcoin, Cryptocurrency, Ethereum, Java
Solutions Architect
2024 - 2024
MailHub Inc
- Designed the overall marketplace platform for buyers and sellers to transact with each other.
- Provided detailed estimates and technical guidance to best meet the original vision.
- Drove the overall solution definition of such a large international trade and shipping project.
Technologies: API Integration, Leadership, Technical Leadership, Agile, Database Architecture, Architecture, Web Development, Mobile Development, Stripe, Stripe API, Reporting, Decentralized Systems, Web Scalability
Blockchain Expert
2022 - 2023
Consulting Client
- Designed a private ledger platform based on FileChain (Filechain.com) to list real estate assets with on-chain documents describing assets to prove existence (record official documents) and to track activities on those assets.
- Implemented fractional ownership with many accounts and their digital signatures to enable multiple owners to formally own a single asset with their respective shares of each property.
- Deployed a FileChain treasury where each user was assigned a private key to digitally sign all activities and be able to cash out any return on investment down the road.
- Implemented drag and drop for official administrations to record directly on this private ledger all documents shared with end-to-end privacy and relevant parties to act as oracles in a Chainlink setup—but way more performant and cost-effective.
Technologies: Blockchain, FileChain, Tokenization, Real Estate, End-to-end Privacy, Technical Project Management, Data Strategy
Architect | Principal Engineer
2011 - 2022
CyanConnode
- Implemented RESTful APIs and optimized database settings for millions of devices deployed nationwide in last mile smart cities to authenticate themselves and to transfer gigabytes of highly confidential data daily for smart-metering applications.
- Served as the lead design authority and delivery manager for the mesh part of the world's largest machine-to-machine (M2M) contract; it was a £1.5 billion SMIP project with the UK government.
- Led the specification, architecture, and software design of a platform that managed millions of devices connected over self-forming radio mesh networks with a state-of-the-art public key infrastructure (PKI) for the internet of things (IoT).
- Prioritized all resource allocations and the backlog for the CyanConnode engineering team and two outsourcing partners for each 2-week agile sprint to deliver all roadmap milestones on time.
- Acted as the main technical interface with Reliance, a $70 billion revenue company, to design and deliver sustainable smart-city networks for the growing Indian market.
Technologies: Constrained Application Protocol (CoAP), Java, 802.11S Mesh Networking, Radio Frequency (RF) Protocol, Embedded Java, Business to Business (B2B), Eclipse IDE, Open Source, Architecture, Team Building, Strategy, Startups, Databases, Team Management, Large-scale Distributed Systems, Software, Design, Planning, Resource Management, Storage, Large Data Sets, Performance, REST, Telecom Equipment & Solutions, Git, SQL, MySQL, Leadership, APIs, Software Design, Serverless, System Architecture, Requirements Analysis, Requirements, REST APIs, Software Development Lifecycle (SDLC), Software Development Toolkits (SDK), Embedded C, Firmware, Firmware over the Air (FOTA), Technical Product Management, CTO, Python, Back-end, Big Data, Data Processing, Low Latency, Multithreading, Elasticsearch, Oracle, Microservices, SSL, Hibernate, Amazon Web Services (AWS), Full-stack, Web Development, HTML5, Team Leadership, C#, Management, Teamwork, Cross-functional Team Leadership, CSS, Solution Architecture, Distributed Architecture, Integration, Jira, GitHub, Hardware, Full-stack Development, Technical Leadership, Project Management, Software Architecture, DevOps, Java 11, API Development, Key Performance Indicators (KPIs), Node.js, Scalable Application, Scalable Architecture, Mobile, DNS, Algorithms, Early-stage Startups, Data Privacy, Agile Delivery, B2B, Engineering, Product Growth, Engineering Management
Principal Engineer
2010 - 2011
ByteActive
- Optimized the performance of the software to reach a highly competitive throughput for storage and restoration of files and data volumes in the petabyte range.
- Led the architecture and implementation of a multi-tier and high-performance cloud service to store petabytes of highly encrypted and compressed data for public and private cloud storage providers.
- Contributed to the engineering effort with more than 50,000 lines of production-ready code, mentored and onboarded other engineers in the team.
Technologies: Java, C++, Storage, Databases, Large-scale Computing, Large Data Sets, Performance, Performance Tuning, Business to Business (B2B), Open Source, Strategy, Startups, Team Management, Business to Consumer (B2C), Software, Design, File Systems, Leadership, Software Design, System Architecture, Requirements, IT Strategy, Python, Back-end, Data Processing, Low Latency, Multithreading, Oracle, Team Leadership, C#, Teamwork, Solution Architecture, Distributed Architecture, API Integration, Full-stack Development, Technical Leadership, Software Architecture, Cryptography, API Development, Scalable Architecture, Early-stage Startups, B2B, Engineering, Product Growth, Engineering Management, Web Scalability, Data Strategy
Lead Engineer and CTO
2008 - 2010
Qobuz
- Audited the engineering group's processes, strengths, and weaknesses to identify key employees, appropriate software, and delivery processes to turn the engineering group into a result-oriented team in less than two months.
- Led the overall re-architecture and refactoring of the Qobuz music website—like Spotify with high-def audio—to achieve a tenfold performance improvement of loading page time, consolidation of multiple frameworks, and support for multisite redundancy.
- Oversaw all Java core back-end services and APIs to import millions of soundtracks in high-quality audio files and metadata from all major labels and made them available for streaming and downloading under multiple subscription and payment models.
Technologies: Java, Streaming, eCommerce, Payment APIs, Media, REST, Business to Business (B2B), Linux, Eclipse IDE, Open Source, Performance Tuning, Architecture, Team Building, Strategy, Startups, Databases, Team Management, Large-scale Distributed Systems, Business to Consumer (B2C), Software, Design, Planning, Resource Management, Large Data Sets, Performance, JavaScript, SQL, HTML, Leadership, APIs, Software Design, System Architecture, Requirements Analysis, Requirements, REST APIs, Technical Product Management, CTO, Back-end, Big Data, Data Processing, Low Latency, Multithreading, Microservices, SSL, Java EE (Jakarta EE), Full-stack, Web Development, HTML5, Team Leadership, Management, Teamwork, Solution Architecture, Distributed Architecture, API Integration, Full-stack Development, Technical Leadership, Project Management, Software Architecture, API Development, Key Performance Indicators (KPIs), Scalable Application, Scalable Architecture, Mobile, Algorithms, Early-stage Startups, Social Networks, Agile Delivery, Engineering, Product Growth, Engineering Management, Technical Project Management, Web Scalability
Principal Engineer
2002 - 2008
Ipsum Networks and Iptivia
- Led the build of Route Dynamics: a high-performance web-based solution for high-fidelity collection, analysis, and display of routing information in IP networks; it has multimillion-dollar sales to service providers and large financial institutions.
- Hired 20+ highly skilled engineers (using recruiters, referral bonuses, and competitive compensation packages) in a challenging job market and maximized engineering team efficiency by fostering collaboration.
- Implemented critical software for path computation and routing protocols (OSPF, IS-IS, BGP, EIGRP) to record and filter millions of network events per minute to isolate actionable notifications to NOC engineers for the largest telco operators.
Technologies: Java, IPTV, Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), EIGRP, IS-IS, IP Routing, IPv6, IPv4, Telecom Equipment & Solutions, Business to Business (B2B), Eclipse IDE, Open Source, Embedded Java, Architecture, Team Building, Startups, Team Management, Large-scale Distributed Systems, Software, Design, Planning, Resource Management, Performance, REST, Leadership, APIs, Software Design, System Architecture, Requirements, Software Development Lifecycle (SDLC), Software Development Toolkits (SDK), Back-end, Data Processing, Low Latency, Multithreading, SSL, Management, Teamwork, DNS, Early-stage Startups, Engineering, Engineering Management
Senior Software Engineer
2001 - 2002
Desana Systems
- Implemented several key performance optimizations of the IP stack, VLAN switching, and spanning tree protocol with hardware-based switching equipment in C/C++.
- Improved the embedded and distributed architecture to monitor thousands of concurrent HTTP transactions for websites hosted in business-critical, high-capacity data centers.
- Designed and implemented the command line interface CLI for layer-2/3 devices (monitoring and provisioning of IP interfaces and VLAN ports).
Technologies: Architecture, Java, C, C++, IPv4, IPv6, SNMP, Open Source, Embedded Java, Startups, Databases, Team Management, Large-scale Distributed Systems, Software, Design, Planning, Telecom Equipment & Solutions, File Systems, APIs, Software Design, System Architecture, Requirements, Embedded C, Firmware, Back-end, Data Processing, Low Latency, Teamwork, Hardware, Early-stage Startups, Engineering
Senior Software Engineer
1998 - 2001
Alcatel-Lucent Enterprise
- Led a team to build one of the first access products in the world with support for MPLS VPNs (label distribution LDP and RSVP-TE).
- Designed and integrated an IPSEC stack to provide IP authentication and encryption to access routers.
- Led a performance optimization effort for +20 software engineers to increase tenfold the number of calls per second of the backbone E10 ATM broadband switch-and-call servers using a flow control analysis and thread profilers.
- Implemented part of the user signaling layer (UNI, PNNI, IISP and SAAL) to help unleash the internet and massive cross-continental traffic volumes between tier-1 large ISPs.
Technologies: C++, C, Java, Performance Tuning, Software, Design, Planning, Resource Management, Performance, Telecom Equipment & Solutions, APIs, Software Design, Requirements Analysis, Requirements, Software Development Lifecycle (SDLC), Embedded C, Firmware, Back-end, Low Latency, Teamwork, Cross-functional Team Leadership
Experience
Web 3.0 Decentralized Social Network and Marketing Platform
https://veesocial.com/A fully decentralized social network and marketing platform based on challenges proposed by brands and influencers.
I was the lead developer of this blockchain application built on top of a next-generation enterprise ledger FileChain (Filechain.com) with full identity management, NFTs for rewards, true end-to-end privacy so no single entity can control nor monetize all the personal data of users, nor being liable for all that data either. The first application built for Vee Social for its crowd-funding was delivered in just four weeks (from design to deployment).
I was the lead developer of this blockchain application built on top of a next-generation enterprise ledger FileChain (Filechain.com) with full identity management, NFTs for rewards, true end-to-end privacy so no single entity can control nor monetize all the personal data of users, nor being liable for all that data either. The first application built for Vee Social for its crowd-funding was delivered in just four weeks (from design to deployment).
Payment APIs to Download and Stream High-definition Music
https://www.qobuz.com/We needed APIs to drive the user payments on the Qobuz music eCommerce platform to stream and download high-definition music tracks from a catalog of millions of songs from all major music labels.
I implemented the APIs and performed critical SEO and user behavior analysis to fine-tune the overall user experience to not lose any potential online purchase during the payment steps, both from web desktop browsing and mobile devices.
I implemented the APIs and performed critical SEO and user behavior analysis to fine-tune the overall user experience to not lose any potential online purchase during the payment steps, both from web desktop browsing and mobile devices.
Pure Java Routing Analytics Engine
https://en.wikipedia.org/wiki/Network_monitoringA 100% Java-based engine to compute routing paths in large IP networks.
I was the lead developer and architect who computed and constantly monitored thousands of OSPF, BGP, and EIGRP routes by listening to all routing advertisements made by routers every second to isolate network misconfigurations in large service provider networks such as AT&T, British Telecom, France Telecom, and so on. This implementation also required a patch to the Linux kernel for the TCP stack.
I was the lead developer and architect who computed and constantly monitored thousands of OSPF, BGP, and EIGRP routes by listening to all routing advertisements made by routers every second to isolate network misconfigurations in large service provider networks such as AT&T, British Telecom, France Telecom, and so on. This implementation also required a patch to the Linux kernel for the TCP stack.
User-to-user Coin-based Marketplace
A user-to-user marketplace for individuals to buy and trade with each other using a utility coin and integration with fiat payment rails.
End-to-end privacy for sharing documents between users (over a zero-knowledge platform) is also enabled for all users to share sensitive information end-to-end after onboarding.
End-to-end privacy for sharing documents between users (over a zero-knowledge platform) is also enabled for all users to share sensitive information end-to-end after onboarding.
Education
1995 - 1996
Master's Degree in Artificial Intelligence
CNRS - France
1992 - 1995
Master's Degree in Informatics and Applied Mathematics
ENSEEIHT - France
1992 - 1995
Master's Degree in Computer Science
ENSEEIHT - France
Skills
Libraries/APIs
REST APIs, API Development, React, Node.js, Web3.js, Stripe, Stripe API
Tools
Eclipse IDE, Jira, GitHub, Git, Terraform
Languages
Java, CSS, HTML5, JavaScript, HTML, TypeScript, Java 11, C++, SQL, Embedded C, C, PHP, Python, Solidity, C#, GraphQL, Rust
Frameworks
Spring Boot, Spring, Windows PowerShell, Hibernate, gRPC
Paradigms
REST, Management, Scalable Application, B2B, Requirements Analysis, Microservices, Radio Frequency (RF) Protocol, Service-oriented Architecture (SOA), DevOps, Database Design, Agile, Mobile Development
Platforms
Blockchain, Blockchain Platforms, Linux, Oracle, Java EE (Jakarta EE), Ethereum, Docker, Amazon Web Services (AWS), Decentralized Exchanges (DEXs), Azure, Mobile, Shopify, Hyperledger, Cardano
Industry Expertise
Project Management, Banking & Finance, Trading Systems
Storage
Databases, PostgreSQL, MySQL, MongoDB, Elasticsearch, Redis, Database Architecture
Other
Open Source, Decentralized Systems, Non-fungible Tokens (NFT), Web 3.0, Constrained Application Protocol (CoAP), 802.11S Mesh Networking, Embedded Java, Performance Tuning, Architecture, Startups, Team Management, Large-scale Distributed Systems, Software, Design, IPv4, Leadership, APIs, Software Design, System Architecture, CTO, Back-end, Low Latency, Multithreading, Full-stack, Web Development, Blockchain Design, Smart Contracts, Blockchain & Cryptocurrency, Team Leadership, Teamwork, Cross-functional Team Leadership, Solution Architecture, Distributed Ledgers, Distributed Architecture, Decentralized Finance (DeFi), Decentralized Applications, API Integration, Crypto, Full-stack Development, Technical Leadership, Software Architecture, Key Performance Indicators (KPIs), Scalable Architecture, DNS, Algorithms, Early-stage Startups, Privacy, Data Privacy, Agile Delivery, Engineering, Product Growth, Filecoin, Web3, Digital Asset Management, End-to-end Privacy, Engineering Management, Technical Project Management, Back-end Development, Data Strategy, Industry 4.0, Team Building, Strategy, Business to Consumer (B2C), Resource Management, Streaming, eCommerce, Open Shortest Path First (OSPF), Border Gateway Protocol (BGP), EIGRP, IS-IS, IP Routing, IPv6, File Systems, Requirements, Software Development Lifecycle (SDLC), Software Development Toolkits (SDK), Firmware, Firmware over the Air (FOTA), Technical Product Management, Big Data, Data Processing, SSL, Decentralized Autonomous Organizations (DAO), Integration, Bitcoin, Cryptocurrency, Governance, Hardware, Central Bank Digital Currency (CBDC), Cryptography, Fintech, Cryptocurrency APIs, Social Networks, Web Scalability, Industry 4.0, User Interface (UI), Business to Business (B2B), Planning, Lambda Functions, Artificial Intelligence (AI), Neural Networks, Storage, Large-scale Computing, Large Data Sets, Performance, Payment APIs, Media, IPTV, Telecom Equipment & Solutions, SNMP, Large Networks, Large-scale Projects, Card Payments, Mobile Payments, Serverless, IT Strategy, ERC-20, Ethereum Smart Contracts, CSS Grid, Applied Cryptography, Digital Banking, ISO 20022, General Ledgers, Progressive Web Applications (PWAs), Advisory, FileChain, Tokenization, Real Estate, Reporting, Solana, Project Discovery, Project Budget Management, Agentic AI, Permissioned Blockchain, Marketplaces
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.
1
Share your needs
Discuss your requirements and refine your scope in a call with a Toptal domain expert.
2
Choose your talent
Get a short list of expertly matched talent within 24 hours to review, interview, and choose from.
3
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