Firefox – You can right click and select 'Page Source' or you can navigate to your 'Tools' menu, select 'Web Developer,' and click on 'Page Source.' The keyboard shortcut is Command + U.You also can right click on the webpage and select 'Show Page Source.' Safari – The keyboard shortcut is Option+Command+U.You also can right click on the webpage and select 'View Page Source.' Then click on 'Tools' and select 'View Source.'
Or you can click on the weird-looking key with three horizontal lines in the upper right hand corner. While holding down the CTRL key, press the 'u' key.) Alternatively, you can go to the 'Firefox' menu and then click on 'Web Developer,' and then 'Page Source.'
