T3rnel Browser is a browser extension + MCP bridge that turns the browser you are already signed into into an inspectable, automatable workspace for developers and their AI agents.
What it does
- Hover over any element and copy its real CSS as Tailwind, styled-components, Emotion, CSS Modules, SCSS, or a JSX style object.
- Capture full pages, including inner-scroll app shells like Claude, ChatGPT and most dashboards, and export as PNG, JPG, WebP, or dark/light-aware PDF.
- Inspect React components under the cursor: props, hook state, and source position.
- Clear forms in one click without breaking React's value tracker, or fill them with your own test form data.
- Record and replay browser interactions: clicks, scrolls, keystrokes, form fills and navigation.
- Export recorded flows as Playwright, Cypress, Puppeteer or Selenium test scripts.
- Clear the cache and hard-reload the current page.
- Stop infinite scrolling on feeds and release one more batch when you want it.
- Give any MCP client access to a signed-in browser with a human approval gate and secret redaction — all local.
Why signed-in matters
Most browser automation launches a fresh browser. That browser has no sessions, no cookies, and no way through the login walls that protect real work. T3rnel runs inside the browser you already use, so the pages you are signed into stay signed in, and a human can see and stop anything the agent tries.
Pricing
Free forever for the core inspection, capture, markdown viewer, network/console capture, accessibility audit, record and replay, and base MCP tools. Pro is a one-time purchase for export formats, the full annotation suite, code generation and test-script export, the encrypted vault, DOM compression, the LLM firewall, live shadow testing and time-travel debugging.
Install it
- Product site: https://t3ratech.github.io/t3rnel-browser-plugin/
- Chrome Web Store: https://chromewebstore.google.com/detail/t3rnel-browser/egpckhdpkoeimoekciejbmbbcackhdmd
- Firefox add-on: https://addons.mozilla.org/en-US/firefox/addon/t3rnel-browser/
- Opera Add-ons: https://addons.opera.com/en/extensions/details/t3rnel-browser/
- Microsoft Edge Add-ons: https://microsoftedge.microsoft.com/addons/detail/t3rnel-browser/dnplmolfblplbeclnglmjamppekpbcjo
- npm bridge: https://www.npmjs.com/package/@t3ratech/mcp-session-bridge
- GitHub: https://github.com/t3ratech/mcp-session-bridge
- Skills: https://github.com/t3ratech/mcp-session-bridge/tree/main/agent-skills
Top comments (1)
Hi DEV community — Tsungai here from TeraTech Solutions. We built T3rnel because we kept watching AI assistants ask users to copy cookies, install headless browsers, or spin up a second login just to get real work done. The browser you already trust already has your sessions, your extensions, and your preferences, so we made it programmable. Still learning how to explain "local-first MCP bridge" without scaring people away, but the feedback here is already helping.