xrmfastdev

WebSocket proxy server for Power Apps local development. It bridges requests from xrmfastdev-client's ProxyXrmAdapter to a real, logged-in Chrome session via the Chrome DevTools Protocol — so your localhost app talks to live Dataverse with no CORS issues and no mocking.

Part of XRM Fast Dev.

Install

npm install --save-dev xrmfastdev

Ships a xrmfastdev-proxy bin, so you can also run it with npx xrmfastdev-proxy.

Usage

1. Start Chrome with remote debugging

chrome.exe --remote-debugging-port=9222 \
  --user-data-dir="%USERPROFILE%\XrmDevProfile" \
  https://your-org.crm.dynamics.com

Log in to your Model-Driven App or Power Pages portal in that window.

2. Start the proxy

npx xrmfastdev-proxy --verbose

Expected output:

=== XRM Fast Dev - Proxy Server ===

Configuration:
  Chrome CDP Port: 9222
  WebSocket Port:  8080
  Verbose:         true

[CDP] Connecting to Chrome at http://localhost:9222...
[CDP] Connected to Chrome browser
[CDP] Found Power Apps tab: https://your-org.crm.dynamics.com/...
[CDP] Detected page type: model-driven

✓ Proxy server is ready!
  Clients can connect to: ws://localhost:8080

CLI options

Usage: xrmfastdev-proxy [options]

  --cdp-port <port>   Chrome DevTools Protocol port (default: 9222)
  --ws-port <port>    WebSocket server port (default: 8080)
  --verbose, -v       Enable verbose logging
  --help, -h          Show this help message

Programmatic usage

import { CdpClient, WebSocketServer } from 'xrmfastdev';

const cdpClient = new CdpClient({ cdpPort: 9222, verbose: true });
await cdpClient.connect();

const wsServer = new WebSocketServer(cdpClient, { port: 8080, verbose: true });
wsServer.start();

process.on('SIGINT', async () => {
  wsServer.stop();
  await cdpClient.disconnect();
  process.exit(0);
});

How it works

The proxy auto-detects the page type of the connected Chrome tab:

• Model-Driven App (window.Xrm.WebApi present) — calls Xrm.WebApi[method](...) directly.
• Power Pages Portal (window.webapi present) — issues fetch('/_api/...') requests, automatically attaching the __RequestVerificationToken for POST/PATCH/PUT/DELETE.

Each WebSocket request { id, method, args } is executed in the browser via page.evaluate() and answered with { id, success, result | error }.

Requirements

• Node.js >= 18
• Google Chrome / Chromium started with --remote-debugging-port
• Runtime dependencies: puppeteer-core, ws

Troubleshooting

| Symptom | Fix | |---------|-----| | ECONNREFUSED on 9222 | Chrome isn't running with --remote-debugging-port=9222; use a separate --user-data-dir. | | "No Power Apps tab found" | Navigate to a Model-Driven App or portal page and log in, then retry. | | Portal mutations return 401/403 | The anti-forgery token wasn't found — refresh the portal page so the hidden __RequestVerificationToken input is present. |

License

MIT © Albert Halchanskyi