What do you want to find out about your site? There are plenty of tools out there so you need to be specific with what you want to audit in your site? There's Google Analytics if you want to find out more about your site's traffic, where you are getting it and how much on a daily or weekly basis. There's also Traffic Travis if you want to find out if you have good on-page SEO or your current ranking for your target keywords. Hope that helps. Have a good day!
If you want to check your website's SEO then I suggest Traffic Travis. This tool comes with a free version that you can use to check on your site's traffic potential, backlinks, and ranking for your target keywords. It is also a great keyword research tool. Hope that helps. Have a good day!