What Zynlex does
Zynlex combines a Windows developer browser with an MCP server so an AI coding agent can work in the same visible page as the developer. The agent connects to the Zynlex window rather than launching an isolated browser session. This lets it use the page’s existing login state, observe the same UI, and act on local application bugs while the developer watches.
The primary targets are applications running on localhost and staging environments explicitly enabled for agent access. Production access is blocked. Zynlex also retains browser errors and failed requests, including activity that occurred before the agent connected, so the agent can begin with relevant debugging context.
Developers can press Ctrl+Shift+E to flag an element and attach a note. The agent receives the note and the element reference. A recording mode captures clicks and keyboard actions along with errors or failed requests caused by those actions. Recordings can be converted into Playwright tests for later CI coverage.
How it works
Install the Windows application, open the target app in Zynlex, and connect an MCP client to the zynlex-mcp command. The agent can list available tabs and local development servers, then open or switch to a page. It uses element references from a page snapshot to perform actions.
Each interaction reports page changes and newly observed errors or failed requests. The check operation waits for the page to settle and returns new diagnostic information. The developer can watch actions in the Agent Activity panel, pause the agent to use the page manually, resume it with the intervening changes reported, or stop the connection.
Page text, console messages, and response bodies are passed to the agent as data rather than instructions. Mocks and added request headers are visible in the browser panels as well as to the agent.
Setup and configuration
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Download and run the Windows installer from the project’s release page. It adds zynlex-mcp to the system PATH.
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Register the server with an MCP client. For Claude Code, use:
claude mcp add zynlex zynlex-mcp
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Open the application under test in Zynlex and ask the connected agent to inspect or fix it.
The Zynlex Settings area includes an AI agents section with connection snippets for Codex, Cursor, Antigravity, OpenCode, and other MCP clients. In Settings → Environments, staging targets must be explicitly marked for agent access.
Tools and capabilities
tabs and open list tabs and development servers, then open or switch pages.snapshot returns interactive page elements and references.act clicks, types, selects, presses keys, hovers, drags, uploads files, navigates back, and answers dialogs. One call can contain up to 10 steps.check, errors, and network expose page stability, console output, failed requests, request headers, and response bodies.screenshot captures the viewport, a selected element, or the whole page.viewport emulates phone or tablet dimensions with touch input.wait_for waits for text to appear or disappear, or for the URL to change.mock supplies fake API responses or request headers.eval runs JavaScript in the page.recording retrieves captured steps or a Playwright test generated from them.
Limitations and notes
Zynlex is Windows-only and supports Windows 10 and 11. Its agent-accessible targets are localhost and staging environments enabled in Settings; production is not allowed. It is intended for interactive browser work rather than headless execution, CI runs, Firefox, or WebKit. Playwright remains the option for running the generated regression tests in CI.
The agent operates with the session already open in Zynlex, so the developer’s visible authentication state can be used without putting passwords into prompts. Developers can take control at any time by pausing or stopping agent activity.
