There are many different types of errors webmaster and web designers should check for. Equally there are a multitude of different tools you can use to check web page content and structure. Here we've listed a few of the most common errors.
BROKEN LINKS
This is probably the most common (and most annoying) error website viewers see. At some point you will have clicked a link only to be presented with a 404 errors or something similar. It's good to try and prevent these errors on your own pages.
When looking at an individual web page it's usually quite each to find and fix broken links. You can click every link on the page to make sure it works correctly. If you have a few pages to check you could also use the w3c link checker. This will check several pages at once.
As your site grows so does the problem of checking and fixing all the links it contains.
INCORRECT HTML
You'll need to check the (x)html used in every page of your site is correct. Not doing this could lead to your pages displaying incorrectly in some browsers and could damage your search engine ranking. Again, the w3c provides a helpful html validator which can check each page for you.
SPELLING
Another thing you need to check web page content for is incorrect spelling. This seems obvious and for a small site it can be an easy task. If you're using an editor such as Dreamweaver or FronPage it should tell you about any spelling mistakes. The problem grows when your site has more content and is perhaps being edited by several people or is using a database and server side scripts to store content. At this point the content for each pages isn't all in conventional html files. You can copy and paste all of your content into a word processor so it can check the spelling but this might take a long time for anything other than a small site.
OLD PAGES AND OUT OF DATE CONTENT
Websites are best when they're fresh and current. Search engines like sites which have content is is often updated and so to your viewers. You need to make sure non of your pages are allowed to languish until their content has become out of date and make sure certain specific pieces of information are current. For example, have you made sure all the phone numbers on your site are up to and and that the copyright messages show the right year?
THE WIDER VIEW: BAD CONTENT ADDED BY USERS
Many sites now allow users to make comments or even add whole pages, perhaps using blogging or forum software. This is a valuable addition to a site but can mean you're getting content you don't want. This could include profane or sexual language or even link spamming; the process where a user adds a link many times to the same page to boost their search engine rankings.
To prevent these things from happening many sites use moderation and make users sign up before they can add content. Unfortunately this is too restrictive for some users. The alternative is to check every page to make sure the comments are ok.

DeepTrawl is available for Windows & Mac OSX.
DeepTrawl can help you will all of these issues
To manually check web page content for each of these issues can be a daunting task for except for the very smallest website. That's why DeepTrawl automates this for you. It will check for issues like the ones above and many others. DeepTrawl checks every page of your site with one click and presents you with a single comprehensive report on the quality of your site.
When you see an error which needs to be fixed DeepTrawl makes this really easy by allowing you to view it in your web browser or in the integrated html editor.
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