NE Alt Tags is a Wordpress plugin that allows the user to easily view images throughout your site that doesn't have alternative text assigned to it and update it throughout your whole website.

If there are any images that do not have an alt tag, then it will prompt a message in the admin letting you know how many images there are that don't have alt tags.

Once the image is updated in the Media library, it will automatically update the image on every page/post on the front-end of your website. If an alt tag is given within the content of page/post, then it will not override the old alt tag.