Independent software consulting
Phase Six was founded in 2008 to help businesses solve problems with web-based software. Today it is the home of Patrick Dowell’s and Carmen Krol’s software consulting.
What we do
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Accessibility engineering
Carmen’s practice: helping product teams build and remediate accessible web and mobile products, with the developer guidance and tooling that keeps accessibility in the work, and a close eye on what AI-generated software gets right and wrong about it.
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Crypto and payments infrastructure
On-chain transaction systems and payment rails at scale. Patrick was the tech lead of the EVM transaction manager at Chainlink Labs, and at Coinbase he built the USDC payment system for Shopify on Base, including an ERC-4337 bundler.
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Distributed systems and backend infrastructure
Configuration and platform systems for large fleets, and keeping them reliable when parts fail. Patrick started and led the Facebook team that built MobileConfig, the configuration system behind its mobile apps, published at SOSP 2015.
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AI-assisted software development
Real products built with AI coding agents, and the engineering discipline that makes the results hold up, accessibility included. Patrick has built software full time with AI coding agents since 2025. Carmen’s recent writing looks at what AI-generated software gets right and wrong about accessibility.
Who we are
Patrick Dowell is a software engineer. He co-founded Strategy Mobile, founded Phase Six in 2008, and has since worked at Facebook, YouTube, 0x, Chainlink Labs and Coinbase.
Carmen Krol is a software engineer with more than a decade of experience, including nearly five years on Meta’s central accessibility team.
Get in touch
Email Patrick at patrick@phasesix.net. For accessibility work, you can also contact Carmen through her site.