Since Firefox 57, the --screenshot flag allows you to take screenshots of websites. The basic usage is as follows: /path/to/firefox -P my-profile -headless --screenshot https://developer.mozilla.org/ This creates a full-height screenshot of https://developer.mozilla.com/en-US/ called screenshot.png, in the active directory, with a viewport width of 800px. You can omit -headless when using --screen
![Headless mode - Mozilla | MDN](https://cdn-ak-scissors.b.st-hatena.com/image/square/e51bd6dc33a667d35eb4146698a198e55ff92d6e/height=288;version=1;width=512/https%3A%2F%2Fdeveloper.mozilla.org%2Fstatic%2Fimg%2Fopengraph-logo.72382e605ce3.png)