Messy code is a huge headache for web developers and webmasters and I’m sure that many of you know that the hardest part of the job is to clean this mess. Beautiful and well-structured HTML and CSS documents can be easily achieved by using HTML and CSS validation tools.
Don’t forget to 
subscribe to our RSS-feed, 
follow us on Twitter and 
follow us on Facebook – for recent updates.
You’ll agree that sometimes you can meet unknown errors or other issues while testing your markup and the following validation tools easily fix any problem that might occur. We’ve gathered a list of popular free validation tools (it is a mix of online services with some great Firefox plugins). These great tools will help you make sure that your visitors are experiencing everything on your website in the right way and you have nothing to worry about. Also it is obvious that HMTL and CSS are essential for any website, although we can’t disregard the role of RSS feeds that are also very important for any web project that have a potential to grow and stream fresh media content. So, it has been said that these tools are great helpers for any web developer and webmaster and we’ve got nothing to add except – let’s browse through it.
Online Validation Tools
Of course you have used these legendary W3C tools that are featured below. Every web developer starts the testing process by checking his HTML and CSS code with the help of these two excellent services. Also we’ve added several similar services that provide advanced validation for HTML, CSS and even RSS feeds. Mostly these tools have very user-friendly interface with simple output.
1. W3C HTML Validator
2. W3C CSS validator
3. Feed Validator
4. Validome
5. Weblogs Feed Validator
Firefox Plugins
The second part of our list contains only Firefox plugins that offer validation services similar to the first five above. You should consider such great plugins as the well-known Firebug and Web developer. These two offer a wide range of testing and debugging options which are spiced up with excellent interface and flawless performance. Other plugins can be used only for some specific purposes, such as HTML validating for example, but I guess it makes them easier in usage.
1. Web Developer
2. Firebug
3. CSS validator
4. HTML Validator
5. RSS validator
