Do your legal documents, such as your privacy policy and terms and service page require updating?

If you are using WordPress, check for any vulnerabilities.

Make sure to delete any users that no longer need access to your website backend.

Do any of your links require tracking?

Are your forms all working correctly?

Do you need to exclude any pages from your internal site search?

Do you need to exclude any pages from your website sitemap?

How fast is your site loading? Use webpagetest.org, PageSpeed or Pingdom.

Do you have any broken links?

Do any featured areas need updating?

Are you using the latest plugins or core software versions?

Have you taken any backups?

Do you need to make any content changes? For example, copyright info at the bottom of the page, the years in business, phone numbers, email addresses, addresses, staff members?

Has the focus of your business changed?

Do a plausibility check by asking yourself if you’d expect a certain feature on a similar website.

Ask some friends and collegues to check your site.

Check old articles to see if they are still relevant.

Validate your code with W3C’s HTML, WDG’s HTML, or W3C’s CSS Validator.

If you have ads on your site, do you need to make any changes?

Are there any missing page titles or meta tags (content descriptions)?

Are there any inconsistent styles or formatting?

Are there any typos or grammatical errors?

Are your domain names renewed?

Have you checked how your website looks on different browsers?

Optimize your databases and remove any old post revisions.

Are your images compressed?

Check the Web Developers Handbook or UITest.com.