Back to all companies
Sign in
Back to all companies
ThirdLayer logo

ThirdLayer

Winter 2025Active

Building Dex, the AI Browser Copilot

Save
ThirdLayer logo

ThirdLayer

Winter 2025Active

Building Dex, the AI Browser Copilot

Save
Company details

ThirdLayer is an applied research and product lab building the next interface for human–AI collaboration.

Our first product is Dex, an AI copilot for the browser. Think Cursor for knowledge work, optimized for speed and embedded directly where you work.

Most web agents are built for set-and-forget tasks. But real work is fluid and messy—spread across tabs, tools, and evolving decisions. Dex transforms your browser into an intelligent, multimodal workspace that understands your intent through voice, text, and action. It enhances familiar interfaces, automates tedious steps, and removes the friction of handoffs.

Beneath the surface, Dex is more than a browser agent — it’s a foundation for:

● Long-term, cross-modal memory grounded in real workflows ● A new interaction layer to replace static UI with a collaborative canvas ● Personalization: understanding how individuals approach tasks and navigate software

We're building the infrastructure for adaptive, intent-aware systems that work the way you do.

Location
San Francisco, CA, USA
Founded
Unknown
Category
Artificial Intelligence
YC Directory Pagejoindex.com

ThirdLayer is an applied research and product lab building the next interface for human–AI collaboration.

Our first product is Dex, an AI copilot for the browser. Think Cursor for knowledge work, optimized for speed and embedded directly where you work.

Most web agents are built for set-and-forget tasks. But real work is fluid and messy—spread across tabs, tools, and evolving decisions. Dex transforms your browser into an intelligent, multimodal workspace that understands your intent through voice, text, and action. It enhances familiar interfaces, automates tedious steps, and removes the friction of handoffs.

Beneath the surface, Dex is more than a browser agent — it’s a foundation for:

● Long-term, cross-modal memory grounded in real workflows ● A new interaction layer to replace static UI with a collaborative canvas ● Personalization: understanding how individuals approach tasks and navigate software

We're building the infrastructure for adaptive, intent-aware systems that work the way you do.

Location
San Francisco, CA, USA
Founded
Unknown
Category
Artificial Intelligence
YC Directory Pagejoindex.com
Pro

Upgrade to Pro, then request the ThirdLayer teardown.

This company does not have a completed analysis yet. Choose a Pro plan first, then use one of your 5 monthly research requests to have our agent investigate ThirdLayer. The full teardown, rebuild plan, and technical specs unlock when it lands.

  • Use Pro to request the first ThirdLayer teardown and keep the finished report in your account.
  • Read every completed teardown and rebuild plan already in the database.
  • Unlock implementation-ready technical specs and 5 fresh research requests each month.

Choose your Pro plan

$20/ month

Find one worth rebuilding, get the teardown, open the implementation-ready specs, and use fresh report requests when you want deeper research.

See Pro plans
Full teardown library
Specs for every company
5 fresh requests / month
CLI for agent imports
Startups.RIP — Dead startups, alive ideas
PricingContactPrivacyGot feedback? DM @oscrhong