Aptana Studio

The world’s most powerful open-source web development IDE just got better. Rebuilt from the ground-up. It's now much faster, customizable and includes new features to help you be more productive. Build web applications quickly and easily using the industry’s leading web application IDE. Aptana Studio harnesses the flexibility of Eclipse and focuses it into a powerful web development engine.
Coffee Cup

The HTML Editor is the best choice for anyone who wants to be in control of their websites. And with a real-time preview that updates HTML5 and CSS3 as you code, your site will be ready for the web before you know it. The Free HTML Editor is a trimmed-down version of the CoffeeCup HTML Editor. All core functionality is included, but various cool functions like CSS Menu Designer, Image Mapper, Website Color Schemer, and FTP Upload are only in the full version.
Notepad++

Notepad++ is a free (as in "free speech" and also as in "free beer") source code editor and Notepad replacement that supports several languages. Running in the MS Windows environment, its use is governed by GPL License. Based on the powerful editing component Scintilla, Notepad++ is written in C++ and uses pure Win32 API and STL which ensures a higher execution speed and smaller program size. By optimizing as many routines as possible without losing user friendliness, Notepad++ is trying to reduce the world carbon dioxide emissions. When using less CPU power, the PC can throttle down and reduce power consumption, resulting in a greener environment.
Arachno

Arachnophilia is an open source HTML editor written in Java (because it’s creator, Paul Lutus, boycotts Microsoft products). It can support Unicode and can also help you edit your PHP, Perl, C++, Java, and JavaScript projects. It also has a built-in FTP client to help with deployment. Its last update was in November 2016.

Net Beans

An IDE is much more than a text editor. The NetBeans Editor indents lines, matches words and brackets, and highlights source code syntactically and semantically. It lets you easily refactor code, with a range of handy and powerful tools, while it also provides code templates, coding tips, and code generators. The editor supports many languages from Java, C/C++, XML and HTML, to PHP, Groovy, Javadoc, JavaScript and JSP. Because the editor is extensible, you can plug in support for many other languages.
Araneae

Araneae. Simple and free text editor. Araneae (pronounced ah-RAN-ee-ay) is a simple, yet powerful text editor, providing only the features necessary to create websites and scripts using the latest web technologies. If you can run Windows, you can run Araneae. Use Araneae for free, forever! If you like it, though, I ask that you please support my software development by purchasing one of my other projects.
HTML Kit

Edit, Preview, Validate, Publish and manage Projects in a full-featured editor. Edit with full-control. Code helpers, generators and shortcuts including Zen Coding are there when you need them. Out-of-the-box version control and backups give you quick access to revisions without having to configure servers. Preview in the editor (full-screen or split-screen live previews), in another window, on multiple monitors, in multiple browsers and even through external devices (multi-device live preview on smartphones/tablets including iOS, Android, Windows Phone and Blackberry). Save time and catch errors quickly by previewing as you edit HTML5, Markdown, LESS and other file types. Built-in HTML Tidy can point out invalid markup and suggest improvements. Or use industry-standard W3C HTML/CSS Validators with a single click. Displaying color below each HTML/CSS hex/rgb() color, highlighting of matching block, instant viewing of matches as you select, and searches within tags / attributes / classes / styles are some of the many powerful tools included, in addition to optional plugins. Keep multiple projects open at the same time (with color labels in tabs), create virtual folders to logically organize files from multiple sources and access local/network/FTP folders. Or skip all of it and simply open files from local folders.
Page Breeze

Get your FREE copy of PageBreeze, our award-winning Free HTML Editor! PageBreeze Free HTML Editor is an award-winning HTML Editor which has both visual (WYSIWYG) and HTML tag/source modes. PageBreeze Free HTML Editor's design emphasizes simplicity and ease-of-use. You'll find that you'll be creating great looking websites almost instantly--with virtually no learning curve! PageBreeze Free HTML Editor is a completely free download for personal use and will never expire. Get your free copy now (approx. 8 MB). Version 5.0 is now available! A full-featured but easy to use visual (WYSIWYG) HTML editor for creating web pages. Version 5.0 has a completely updated editor with many new features and support for the latest HTML standards. Our freeware visual editor is actually powered by Microsoft Internet Explorer. So you can always be sure you are seeing exactly what you will get. Color-coded HTML source (tag) editor. You can switch between HTML source and visual modes at any time with a click of the mouse, and any changes you have made will instantly be reflected in both modes. Preview mode lets you instantly see what your finished web page will look like in Microsoft Internet Explorer. Included webpage templates and direct access to hundreds of free website templates to give you a fast start on creating a great looking site. Point and click form building tools make it fast and easy to create powerful web forms. Built-in integration with our form processing service, so you can make your web forms work almost instantly with no programming, scripts, or technical knowledge required. Built-in in integration with our web knowledgebase, so you can easily add a 24x7 customer service system that will answer your customers' questions instantly.
Sea Monkey

The SeaMonkey project is a community effort to develop the SeaMonkey all-in-one internet application suite. Such a software suite was previously made popular by Netscape and Mozilla, and the SeaMonkey project continues to develop and deliver high-quality updates as well as new features and improvements to this concept. Containing an Internet browser, email & newsgroup client, HTML editor, IRC chat and web development tools, SeaMonkey is sure to appeal to advanced users, web developers and corporate users. SeaMonkey is built on the open source Mozilla Gecko engine, the same code which underlies the highly successful Thunderbird and is the base for the Firefox browser. SeaMonkey benefits from the cross-fertilization with these other projects, by gaining (and contributing) new features and the ongoing security updates which are a modern necessity. The SeaMonkey Association provides legal backing for the SeaMonkey Project.