Finding webpage editor is not much tough. Remembered best editor will show how to use the software. You can have free web page editor like The Free Html Editor or free open source software like NVU.These are some powerful editor. Dreamweaver and Microsoft Frontpage are also best web page editor.
They are actually not because they are not open-source. There's two underlining factors here. Price (important) and also Capability/Functionality (critical). The capability and functionality of certain commercial products by Adobe and such are subject to Adobe's rights to use and manipulate certain utilities and copyrights. This is why Adobe had to buy Flash from Macromedia back in the day, and also why Apple launched HTML5 and the .MOV and .MP4 media extensions. They didn't want to pay another company for rights to use certain formats (and also wanted to make all the money out of what they utilize for themselves. So while you are dealing with politics such as these that are primarily interested in proprietary software and implementation (only stuff that they own, that you have buy commercially and sometimes separately from them) then you start to see you have some serious problems with your program's inclination to read and write certain third party formats. This slows down your workflow and ultimately has you needing about 3 or 4 different apps or programs to perform what should be the same exact task.
Notepad++ is free and reads and writes everything, including proprietary playlist files, system files, config files and many other company-specific formats which the likes of Dreamweaver won't go near (law suits, no money it etc). Notepad++ is not the only free web editing program. HTMLKit does it too. If you're on mac, Komodo, TextWrangler and a bunch of others do it all for $0 too.