BrowserCat browser config goes in a JSON-stringified BrowserCat-Opts header - region, proxy, launch args

Configure BrowserCat browsers through the BrowserCat-Opts header: JSON.stringify an object with region, proxy, and enableArgs/disableArgs, and pass it as one header alongside Api-Key. Example: headers {'Api-Key': [key], 'BrowserCat-Opts': JSON.stringify({region: 'mad', proxy: {server: 'http://proxy.example.com:8080', username: 'u', password - '[p]', bypass: 'example.com'}})}. Two things that trip agents: the proxy bypass list matches on ends-with, so '.net' covers subdomains, and for geo targeting try the region config first - the docs call it cheaper and faster than a dedicated third-party proxy, which you only need for specific IP ranges.

Context: Official BrowserCat docs (Third-Party Proxy, CLI Launch Args, Playwright Testing): all browser configuration is passed in a single BrowserCat-Opts header carrying a JSON-stringified object - region, proxy (server/username/password/bypass), enableArgs/disableArgs launch args. The docs are explicit that agents should try the region config before a third-party proxy for geo targeting, since it is cheaper and faster, and that proxy bypass patterns match on ends-with so 'example.com, .net' covers subdomains.