About
Making building codes legible
Building codes and zoning ordinances are public law — they decide what you can build on your own land. But they live in thousands of PDFs and code-publisher portals, written in language that takes professionals years to learn to navigate. GoCodebook exists to close that gap: ask a question about a property, get a plain-English answer with the exact controlling citation, and read the verbatim code section yourself.
What we build
GoCodebook is three layers that keep each other honest. How each one is sourced and checked is documented in our methodology.
The Code Library
The verbatim enacted text of 794 California codes and ordinances — 289,000+ sections, kept in the original title/chapter/section structure. We don't paraphrase this tier.
Read the code textPlain-English guides
A written guide for every jurisdiction and topic we cover — 540 cities and counties, Title 24, and the state housing laws — each drafted from that place's own code text.
Browse CaliforniaThe research assistant
Ask about a specific address or project and get an answer that cites the controlling sections, with links back into the verbatim text so you can check the work.
See how it works540
Cities & counties
794
Codes & ordinances
289,000+
Code sections
13
Parts of Title 24
Why we built it
The information is public, but it isn't accessible. A homeowner asking whether they can add a unit out back, a contractor checking a setback before pouring, an architect confirming which edition of Title 24 governs a permit filed this month — all of them are looking for one or two sentences buried in a code no one reads front to back. The usual answers are a forum post, a search result about a different state, or a phone call that takes three days to return.
Meanwhile the rules genuinely differ at every city line, and the state layer keeps moving: new housing legislation each session, a fresh Title 24 edition every three years. Getting this right isn't a matter of reading harder — it's a data problem. So we built the corpus first, put the verbatim text in front of people, and only then let an assistant answer on top of it.
What we believe
Checkable, not just plausible
Every answer points at the section it came from. If you can't get from the answer back to the enacted text, we haven't finished the job.
The law as published
The library tier is the ordinance as the jurisdiction published it — same structure, same wording. Summaries live in a separate layer, clearly marked.
Honest about the edges
When the code is silent, or a page hasn't been re-checked recently, we say so. Dates and status labels are on the page, not buried.
Who we are
GoCodebook is built by a small team that spans software and architecture practice. It was co-founded by Sungjoon Nam (CEO) and Sunwoo Kim (CSO), a licensed architect with U.S. practice experience — so the product is shaped by people who have actually had to find the controlling code section before a submittal.
Sungjoon Nam
CEO and Co-founder
Sungjoon is a real estate developer with 20 years of experience and the founder of Number Analytics LLC, an AI-powered statistical software company. He has taught as a professor at Rutgers and SUNY Korea, and holds an MBA and a Ph.D. in Quantitative Marketing, both from the University of Chicago Booth School of Business.
LinkedIn
Sunwoo Kim
CSO and Co-founder
Sunwoo is a licensed architect in California and Director of Design at Butler Armsden Architects in San Francisco, with earlier practice experience at Soltos Architects and Skidmore, Owings & Merrill. He holds a Master of Architecture from Yale University and a Bachelor of Architecture from the University of Seoul.
LinkedInGet in touch
GoCodebook, Inc. is based in San Francisco and works with architects, contractors, developers, planners, and homeowners across California. Questions, corrections, or partnerships: contact us — corrections to any page are especially welcome (see how we handle them). You can also find us on X and LinkedIn.
Try it on a real address
Ask what you can build on a specific parcel and see the citations for yourself — or read the verbatim ordinance first and skip the assistant entirely.