KompoZer screenshots show it as a real WYSIWYG editor, and it is available for Linux, OS X and Windows:
Screenshot (source: KompoZer homepage; click for full-size)
KompoZer is a complete web authoring system that combines web file management and easy-to-use WYSIWYG web page editing.
KompoZer is designed to be extremely easy to use, making it ideal for ...
Update (20170929): For the last year I am using the amazing Pinegrow (https://pinegrow.com) IDE and I wholeheartedly recommend it. The BlueGriffon I mentioned below in my reply from few years ago is outdated and far behind the Pinegrow in development.
I recommend BlueGriffon. It is FREE, feature rich, runs on all major platforms, and has many good add-ons, ...
Notepad++ can do this with the nppFTP plugin. Now this isn't cross-platform, but I think it does deserve mention here. (And if no better solutions presents itself, you could even run it under Wine/CrossOver).
When you connect via nppFTP you get a filebrowser in a panel on the right, where you can directly open files from the tree, and changes are directly ...
A dedicated editor for web dev is Adobe Brackets, an awesome piece of open-source software. Here's some features it has you won't find in other editors:
Live preview: You can set it up so that when you make a change in the editor, the change will appear immediately in the browser
Quick edit: You can access the CSS styles affecting an element by simply ...
This answer is no longer valid. As notified in comment by @Dorian, this can no more be used for normal web development.
Google Web Designer is a WYSIWYG html editor and much more.
The design is currently in beta and is available for the following Linux distributions:
Here's the official download link
On the download page select the HTML5/PHP package if you are not interested in Java etc.
When you create a PHP project, you can specify "PHP ...
There's a similar app: AWD. From its description:
A lot of ways to reach your project ( FTP, FTPS, SFTP, WEBDav and growing)
Integration with web server
Autodetection of file's encoding
Amaya is W3C's official WYSIWYG Web editor.
It is open source, and judging by the screenshots, customizable enough. Just in case, it also supports OSX and Windows.
On the home page, it is described thus:
Amaya is a Web editor, i.e. a tool used to create and update documents directly on the Web. Browsing features are seamlessly integrated with the editing ...
It's a web app, but you could try Koding.com. It gives you your own "VM" on the web with about 4GB of space to start with. You can import git repositories or .zip files and supports several other platforms too.
It does do real-time collaboration, which works relatively well, although not quite up to par with Google Docs.
Here is a look at it's main ...
Emacs (home page) meets all your requirements. It's good (this is subjective so I simply assert that it is good; I do use it daily). It's free (it's one of the historical highlights of the free software movement). It's cross-platform (available on just about any Unix variant — get it from your package manager, or more recent versions for OSX, as well as on ...
FileZilla is a good FTP file browser and allows for basic editing as long as you have the correct software install. So for example, if you wanted to edit index.html on your website, you can do you edits in a program like Notepad++(for example), save it, and then upload it back to your website. Plus its cross-platform and open-source.
If you are looking for ...
Brackets is a free, open source editor based on web technologies with a primary focus on web development. It is cross-platform and is backed by Adobe.
Using Live Preview, Brackets pushes code edits instantly to the browser to present an updated page without having to reload. However, Live Preview currently works only on Google Chrome (not even Chromium!). ...
Cyberduck does this with the editor of your choice - you can add editors from "edit -> preferences", simply right-click on a file and select "edit with", and your editor of choice. This would allow you to use your favoured IDE or code editor, like sublime text on files on your website as if it was a locally hosted file (Behind the scenes, it downloads, ...
My ultimate favorite IDE = Netbeans
It's very plain, the more you use it, the more you learn it. Just hit open and open you html files, or drag&drop them from your desktop and you ready to code. Or, start coding right and put your files in a project and let Netbeans handle it for you. Moreover, the editor is ...
WebStorm is a very serious tool for web authoring and development. It comes from a company specializing in a family of powerful IDEs for professional programmers.
WebStorm runs on Linux as well as macOS and Windows. A commercial tool, reasonably priced with active development and support.
WebStorm is able to display live updates as you edit a page ...
I personally would recommend the use of Microsoft's Visual Studio Code. Using this tool allows you to add additional extensions (such as PowerShell syntax),
It meets your following requirement:
Which OS's are supported?
VS Code runs on macOS, Linux, and Windows. See Requirements for the
supported versions. You can find more platform specific ...
JetBrains is a leading provider of developer tools for many languages and platforms.
Commercial product requires purchase of a subscription after an Initial trial period.
Runs on Linux, as well as macOS and Windows. See system ...
Tweakstyle is a relatively new entry in the HTML code editor. It is currently in beta but has a good amount of features.
Uses chrome web tools in the preview pane so you can inspect an element and edit matching rules.
It has a preview pane that updates when you save your HTML file. It provides live updates when you change your CSS.
When you open a HTML ...
You can use Sublime Text editor, with W3C Validator Plugin. Sublime is paid but you can use the trial version without limits. But I would recommend you to buy as its an awesome editor, trust me...
I'll provide a walk through of how this will work..
Open Sublime Editor, install Package Control(If you haven't)
Now install the W3C Validator Plugin using the ...
You can use WebMaster's HTML:
Supports undo/redo feature, built-in virtual keys for tags and popular keyphrases.
Lite version has limited code completion support: you can select only first suggested item.
CRiSP is a multiplatform editor (Mac/Windows/Linux) which can edit files from remote locations (including ftp/sftp support). It caches the files locally so you can edit as normal, and on saving, have the option to auto upload.
CRiSP pretty much contains all the modern features expected of a programmers editor (syntax highlighting, template support, default ...
Ultraedit (and its IDE superset, UltraEdit Studio) is an excellent programming editor; which also has a great native functionality to open/save files to FTP sites.
Linux examples and walkthrough
Windows examples and walkthrough:
Please note that when you open a file from FTP, Ctrl+S will save straight to FTP.
It even has FTP site manager so you don't ...
Music.SE has been trying to push for Lilypond support which has many of the features you have requested.
There is a lot of external support for Lilypond as shown by numerous third-party components, and there's definitely been some interesting integration done with MediaWiki where it not only displays the music, but also plays it.
Here's a simple example:
I would suggest trying Bluefish. It meets some of the criteria you asked for and its a free open source program so if you don't like it your not out anything. It runs on Linux, FreeBSD, MacOS-X, Windows, OpenBSD and Solaris.
I'll recommend Visual Studio Code, it could exists something better than a lightweight code editor from the team that developed the most powerfull and complete IDE environment for programmers (undeniably, unless you have not yet tested. ) ?
Please reffer to the indications in this StackOverflow post to see how to see the preview in the webbrowser:
How to ...
Notepad++ with the plugin TextFX is a free solution. The issue is that TextFX has not been maintained since 2008 and has many known bugs. It does still work and is widely used, people simply put up with the bugs. Another plugin that may be useful is Tidy2. Both of these plugins can be found here. I include these as free options because I am aware of their ...