Welcome to the Q&A Forum

Hi Lepra! Like ViviCa1 recommended, I suggest using Screaming Frog to pull down this data. Along with pulling down a list of your missing H1s, you can see the webpages that might have more than one H1 (which will also negatively impact your SEO)! I highly recommened giving Screaming Frog a try. You can download it here: https://www.screamingfrog.co.uk/seo-spider/ As it was mentioned, if your website has less than 500 URLs you can pull a free Screaming Frog report. If you aren't sure how many pages your website has, you can do a quick check to see how many Google has indexed. In order to check this you can go to Google and search "site:" and then the URL minus the www. (i.e. site:bluecorona.com). This will tell Google to ONLY show pages from this website, thus showing you the number. If it is less than 500, go ahead and use Screaming Frog to pull that report down. Good luck!