A minimal CDP (Chrome DevTools Protocol) client for Elixir, built for Lightpanda.

Why Lightpanda

Headless Chrome carries the full rendering pipeline — CSS parsing, layout, compositing, painting — even when no human is looking at the result. Lightpanda strips all of that away, keeping only the DOM and JavaScript engine, which cuts resource usage by 60-80% for automation workloads.

It's written in Zig for explicit memory control via arena allocators — critical when crawling thousands of pages — with seamless C interop for embedding V8. The custom DOM implementation consolidates allocations and uses compile-time V8 snapshots to cut startup time by 10-30%.

Why LightCDP

Existing Elixir browser automation libraries (playwright_ex, playwright-elixir) route commands through a Node.js Playwright driver. LightCDP talks CDP over WebSocket directly to Lightpanda — no Node.js, no Playwright, no Puppeteer in the middle.

Quick start

{:ok, session} = LightCDP.start()
{:ok, page} = LightCDP.new_page(session)

:ok = LightCDP.Page.navigate(page, "https://example.com")
{:ok, title} = LightCDP.Page.evaluate(page, "document.title")
# => {:ok, "Example Domain"}

LightCDP.stop(session)

See LightCDP.Page for the full interaction API (click, fill, submit, wait_for_selector, wait_for_navigation).

Error handling

All functions return {:ok, result}, :ok, or {:error, exception}. See LightCDP.ElementNotFoundError, LightCDP.TimeoutError, LightCDP.JavaScriptError, LightCDP.CDPError, and LightCDP.ConnectionError.

Lightpanda binary

The binary path is resolved in order:

1. LightCDP.start(binary: "/path/to/lightpanda")
2. Application.get_env(:light_cdp, :lightpanda_path)
3. ~/.local/bin/lightpanda

Install via curl -fsSL https://pkg.lightpanda.io/install.sh | bash.