Quality First
We don't cut corners. Software should work reliably and be maintainable for the long haul. Your future self will thank you.
Quality software.
No exceptions.
We don't compromise on accessibility, performance, or maintainability.
Who We Are
Stubborn Mule is led by Robert DeLuca, an engineer with a track record of building software that matters. Robert has been through two successful acquisitions (Percy by BrowserStack, Enspire), leading SDK development and developer tools at scale.
Before that, he led iOS, Android, and Web teams at Visa Checkout to achieve full WCAG compliance—work that directly supported Visa's enterprise partnerships and demonstrated that accessibility and great user experience aren't competing priorities.
Throughout his career, Robert has shaped product architecture for high-growth startups across fintech, developer tools, and SaaS. Today, Stubborn Mule builds open source tools and works with teams who understand that quality software isn't optional.
2 successful acquisitions (Percy, Enspire)
Led WCAG compliance at Visa Checkout
Product architecture for high-growth startups
How We Work
01
02
Solve Real Problems
We focus on building things people actually need. Not every problem needs a framework, and not every solution needs to be clever.
03
Clear Communication
You'll know what we're working on, why it matters, and when it'll be done. No jargon, no surprises.
What We're Building
Flagship Product
Vizzly
Visual regression testing built for speed and developer experience. Catch UI bugs before they reach production with local-first testing and cloud review.
Local TDD Mode Cloud Review Fast & Simple
Available for Select Work
Technical Advisory
Two acquisitions. Teams scaled from 3 to 30+. Technical decisions that shipped products people actually use. We solve the hard problems: aligning teams, making pragmatic architecture choices, and shipping when it matters.
Fractional CTO Team Building Architecture
Let's Talk
Hands-On Work
Engineering
We write code. Accessible web applications, API design, developer tools, and system architecture. If you need someone who can think strategically and execute tactically, we should work together.
Web Apps APIs Dev Tools
Get in Touch
Open Source Commitment
Over a decade of contributing to open source. From SDKs used by thousands of developers to accessibility-focused libraries, we build tools that solve real problems.
10+
Years Contributing
2
Acquisitions
∞
Developers Helped
Stay hungry.— Steve Jobs
Stay foolish.