AI today lives inside a prompt box—powerful, but disconnected. It can't see your screen, hear your goals, or connect your tools into something greater than the sum of their parts.

We think that's backwards.

ThirdLayer is an applied research and product company building the next interface for AI.

Our first product, Dex, is an browser-native copilot built to transform how people use AI by collaborating, rather than full automation. Dex personalizes itself to your context including your tabs, your tasks, and your tools, helping you move through work with speed and clarity.

We're building a future where AI doesn't replace human intelligence, but expands it. One where your browser becomes an extension of your mind.

We're backed by Y Combinator and leading HCI, deep tech, and consumer tech investors with mentors from Google DeepMind, Sakana AI and MIT Media Lab. Our team comes from—or passed on offers from—OpenAI, top quant firms, FAANG, and other research labs.