We're building AI that makes plan reviewers more effective — not redundant.
Plan review is a profession that requires expertise, judgment, and professional accountability. We didn't build Mason to replace that. We built it because the mechanical parts of code lookup — the parts that can be automated reliably — shouldn't be consuming the time of skilled professionals.
We believe that human oversight remains essential. That's not a disclaimer. It's the foundation of our product philosophy.
Our Philosophy
AI supports — it does not replace — human interpretation and judgment.
We believe that human oversight remains essential in plan review. Mason handles the mechanics of code lookup so your reviewers can do what only they can do: exercise judgment, catch edge cases, and take professional responsibility for the output.
Human oversight by design.
What “Human in the Loop” means at Mason
Mason never submits a comment letter.
Your reviewer always reviews and signs off before anything goes out.
Gray areas are flagged for human attention.
The AI surfaces the question; the reviewer makes the call.
Accuracy data is published and tracked continuously.
We tell you where the model is uncertain; we don't hide it.
The reviewer's judgment is the product.
Mason is the tool that clears the path for it.
Want to talk with the team behind Mason?
Talk to a HumanThe Company
Built on the hard problem.
Mason raised a $4.3M seed round led by the Urban Innovation Fund. We're based in California, focused on residential plan review, and obsessed with the accuracy and reliability problems that have made code-checking software fail for the last fifty years.
Construction-tech writer Brian Potter traced fifty years of failed code-checking projects. The lesson is consistent: shallow rule scripts break the moment reality shows up. We built Mason differently — training large models on large, diverse data, then stress-testing against synthetic edge cases the way Waymo and Cruise stress-test rare driving scenarios.
Half our engineering time goes to evaluation. That's not an accident — it's how you build something that plan check professionals can actually trust.
Want to see what we've built?
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Built by people who understand the work.
Cofounder, CEO
- Early hire for Synopsys' DSO.ai, $XXM in annual revenue.
- Ex-Wealthfront; Sr. Data Scientist, led a team
- Statistician via Berkeley & Oxford
Reach us at founders@withmason.ai
Interested in working with us or partnering?
Talk to a HumanPress & Recognition
In the news.
“We raised a $4.3M seed round led by the Urban Innovation Fund.”
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