Here's some of my favorites
1. General Editors: UltraEdit (commercial) or Notepad++ (free and the closest alternative to UltraEdit IMO)
2. HTML only editor: Kompozer. Its the continuation of the old nvu project and a lot less buggy.
3. Diff Tool: UltraEdit's built in compare utility is best for me. I never really cared for WinMerge or WinDiff. But I do find AptDiff to be an excellent free alternative to UltraEdit's compare.
4. FTP Client: FlashFXP. I just like it
5. Browser Addon: FireFox Web Development Tool bar. MUST HAVE! For anyone wanting to learn CSS or just see how a simple change will affect a site without having to make actual changes, this is the tool to have.
6. Validator: Well the main one at
http://validate.w3.org will check your site for proper validation quickly and correctly.
7. Database Tool: SQLyog & WinMySql are a great free clients for your PC. Phpmyadmin of course is a staple of database development as well.
Some Additional tools:
8.
BigDump - This little script is great for uploading large mysql databases to get past the timeout problem that phpmyadmin has.
9.
PHP Shell - If your host doesn't allow shell access, or requires an arm and your first born to get SSH access, simply use this handy little script.
10.
Net2FTP - Must have tool for any site. Net2ftp is a server-side file manager, ftp client, wysiwyg editor, chmod controller, and much more. You can install your own on your site, or just use the one on their site to point to your FTP server. Uses lots of cool ajax and can almost replace the need for a local ftp app.
11.
PHPInteractive - This is a real simple, yet useful tool to do some sandbox php coding to figure out logic in your php code. Good for developers working on a function and wondering what the result would be. Simply enter some php coding in the top box and submit it, it gives you the result.
12.
NuSphere PHP Debugger - (Commercial) - This tool is a must have for major php developer. I used to just use a text editor to make PHP code, using inline echos and print commands for debug. Now that I use NuSphere, I can crank out new code in a quarter of the time. Debugging is instant, and real-time, letting you see any aspect of the current code, variables, session, post data, etc.
I did recently come across 2 free php debuggers:
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PHP Expert Debugger - Free. Not tested, but looks like a simple yet powerful tool
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CodeLobster PHP Debug Edition - Free. Tested. Worked ok for debugging, but had some hiccups. Devs on the site seem eager to fix them though.