TRUEedit turns the Post HTML Tab into a raw HTML editor that does not texturize or modify your code.
TRUEedit is designed specifically for people who understand HTML and want to format their HTML code for readability. By default WordPress modifies your post content with two filter, this plugin lets you disable those filters along with any other content filters. TRUEedit also enables the inserting of tab characters into the post's content editor. You can even change the font, size and color of the editor, giving you more control over your blog editor.
Keep in mind that by default WordPress texturizes and automatically adds break and paragraph tags into your post content. Which means if you want to put HTML tags on different lines and format your code you could inadvertently be adding break and paragraph tags. Oh No? Use TRUEedit to fix this problem.