David Cumps

About David Cumps

I’m David. I’ve been writing software since 1998, and over the years that has meant a lot of languages: Quick Basic and VB6, then PHP, C# and F#, and these days Python, TypeScript, Go and Rust as well. I pick whatever fits the problem instead of bending the problem to fit one stack. .NET is the one I’ve known longest; I picked it up with the first beta in 2001. Since 2010 I’ve worked as a freelancer through my own company, Cumps Consulting, based near Bruges in Belgium. I’m available for freelance and contract work.

What I can help with

  • Backends and APIs, both new builds and systems that have to keep running for years. Mostly C# and F# on .NET, but also Python, TypeScript, Go and Rust.
  • Software architecture with event sourcing, CQRS and domain-driven design. I’ve run all three in production for government registries.
  • Cloud and platform engineering: Terraform, Ansible, Docker, AWS, CI/CD and monitoring.
  • Technical leadership: leading developers and testers, code reviews, release planning, and moving a team to an open-source way of working.
  • Web3 and crypto infrastructure: brokers, bots and node operations on the Chainflip cross-chain swap protocol.
  • AI-assisted engineering: running a codebase with AI coding agents, a story-driven workflow and adversarial reviews, with a human deciding what ships.

Selected work

The full list, going back to 2003, is on the projects page.

Stablecoin Liquidity Provisioning Bot (2024). First place in the Chainflip General Track of the Cross-Chain Summer Hackathon: a bot that keeps competitive stablecoin limit orders on Chainflip, so liquidity providers earn yield without babysitting a dashboard.

Broker as a Service (2024). A managed Chainflip broker for wallets and DEXs at chainflip-broker.io, with the lowest fee in the ecosystem and an MCP server so AI agents can swap through it.

Swappy (2024). A Discord and Telegram bot for wallet-less, non-custodial cross-chain swaps on Chainflip.

Chainflip (freelance, 2021 to 2022). I built the InfoBot that reports swaps on X, wrote Ansible playbooks and helped set up the AWS infrastructure.

Basisregisters, Digitaal Vlaanderen (2021). I designed and built the Flemish Base Registries, the official source inside the Flemish government for Belgian municipalities and postal codes, Flemish street names, addresses, buildings, parcels and roads. Each registry is its own event-sourced .NET service, with projections to Atom feeds, REST APIs and Redis. The infrastructure is Terraform on AWS, with services on Fargate and monitoring in DataDog. I led the team of developers and testers and moved the project to an open-source model on GitHub.

“David is a great architect on our project. He has thorough knowledge of all the components in play, is always open for feedback and a great team player. The kind of person you want on every project.”

Arne Dumarey, Senior .NET Developer, Digitaal Vlaanderen

Wegwijs, Agentschap Informatie Vlaanderen (2017). A registry of the organisations and bodies in the Flemish public domain, such as municipalities and churches.

Codaba, European Defence Agency (2016). A collaboration platform.

Infrabel (2014 to 2015). Elise/Dice for real-time train movement tracking, the GNaP application framework, an internal NuGet feed, and AppTrack for automated code review.

Before that I worked on a prospection system for Bank van Breda, PDF processing and an RSS aggregator for Mediargus, and the Arta 8 telecom platform at Artilium.

This blog

Over the past year I’ve been moving my family off big tech onto a platform I run myself: email, calendar, photos, passwords and documents, all defined in Terraform and Ansible on European infrastructure. The articles document it as it happens. If you want to see how I work, they’re a fair sample. They cover the design decisions, but also the incidents and what it took to fix them. The archive holds what I wrote on my old blog between 2004 and 2014, mostly C# and .NET.

I’ve also given talks, from ASP.NET security and eID in .NET in 2004 and 2005, during and around my internship at Microsoft Belux, to the opening workshop of Chainflip’s 2024 hackathon.

How I work

I’ve kept the same rules with clients for years. Invoices list what I did in enough detail that you recognise the work. Time I spend learning something for your project is on me. I only build what you asked for, and if I see something worth adding, I tell you instead of slipping it in. When you need to buy something, I recommend what suits you, even if another option would pay me more. Code, passwords and documentation are yours and stay documented, so nothing is lost if we stop working together. And I answer quickly, even if the first answer is only that I’ll look at it later that day.

Skills

  • Languages: C#, F#, Python, TypeScript, JavaScript, Go, Rust, SQL, PHP, Shell
  • .NET: ASP.NET Core, Entity Framework Core, Dapper, NHibernate, SignalR, xUnit
  • Architecture: event sourcing, CQRS, domain-driven design, REST APIs
  • Data: SQL Server, PostgreSQL, MySQL, Redis, Elasticsearch
  • Cloud and infrastructure: AWS (Fargate, RDS, S3, API Gateway), Azure, Terraform, Ansible, Docker, DataDog
  • Front end: Vue.js, React
  • Delivery: Git, GitHub Actions, TeamCity, Octopus Deploy, Scrum, Kanban, Extreme Programming

Get in touch

Email me at david@cumps.eu, or find me on LinkedIn, GitHub and X.

Cumps Consulting SRL, Jabbeke, Belgium. VAT BE 0832.451.624.