Chrome DevTools Protocol (CDP)
The native debugging and automation interface of Chromium browsers, used to inspect pages, drive navigation, and control the browser over a WebSocket.
The Chrome DevTools Protocol is the interface Chromium exposes for inspecting and controlling a running browser. It is the same channel the DevTools panel uses: a WebSocket connection over which a client sends JSON commands and receives events, organized into domains like Page, Network, DOM, Runtime, and Input. Through CDP a program can navigate, read and modify the DOM, evaluate JavaScript, intercept network traffic, capture screenshots, and emulate devices.
CDP underpins most modern browser automation. Puppeteer is a CDP client, and Playwright drives Chromium through it as well. The distinction that matters is between raw CDP, which speaks the protocol directly, and frameworks that additionally inject helper scripts and objects into pages to provide their APIs. Those injected artifacts are part of the page environment and are observable by page scripts, which is relevant in any context where the realism of the browsing environment matters, from fingerprint testing to bot research.
Oculr drives browsers over raw CDP by design, with no injected automation frameworks, because injected globals would undermine the engine's native-getter consistency. Runtime overrides for timezone, locale, language, and geolocation re-apply automatically on every new tab and reload. Launching a profile also returns a WebDriver-compatible driver path plus the CDP WebSocket endpoint, so existing Selenium, Puppeteer, and Playwright scripts attach unchanged.
