The best development browser available. Combine with YSlow, SmushIt! and Firebug for an all singing all dancing web development experience. Link to Download

Google's new web browser - lightweight and fast. Link to download

Microsoft's effort at a web browser - useful for checking your code works on their platform. Link to download

Excellent free image viewer with excellent batch processing capabilities. Link to download

An excellent pair of tools for analysing your site - minimise those graphics and sort out your code to improve page load speed. Link to download

Subversion software allows you to download/upload the program source code from the latest release (which may be under construction or in testing)

An excellent tool which interfaces directly with Windows Explorer.

Download

An excellent tool which with multi-platform capability.

Download Or direct from Linux repositories using apt/Synaptic

For Mac OS users

Download

Another Firefox addon which will validate the HTML output of your pages. Be warned you may be in for a shock on how much work you need to do to be valid! Link to download

Link to validator

For those people who like coding 'old school' style or need to make specific code changes.

Download

Download

Download

Read this section on how to set up a local copy of of your online store.

Turnkey Linux provides a very quick method to start a webserver.

MAMP (Mac-Apache-MySQL-PHP) is a one-click solution for setting up your own webserver under Mac OS X.

WampServer is a Windows web development environment. It allows you to create web applications with Apache, PHP and the MySQL database. It also comes with PHPMyAdmin to easily manage your databases.

WampServer installs automatically (installer), and its usage is very intuitive. You will be able to tune your server without even touching the setting files. Download WAMP Server

XAMPP

EasyPHP

An open source file comparison tool. Link to download

An open source file comparison tool. Home Page Or from Linux repositories using apt/Synaptic

This software has a free 30 day trial but then must be purchased. $30 for basic. $50 for pro. Link to download

Open source MAC comparison tool. Link to download

FileZilla Client is a free, open source FTP client. It supports FTP, SFTP, and FTPS (FTP over SSL/TLS). The client is available under many platforms, binaries for Windows, Linux and Mac OS X are provided. Filezilla Download

FireFTP is a free add-on for the Mozilla Firefox web browser. The layout is similar to the popular Windows-based “WS_FTP” program, but FireFTP runs completely within Mac, Linux, and Windows versions of Firefox. FireFTP Download

Avast Anti-Virus

Search & Destroy

Linux Malware Detect

Malwarebytes

Ant Renamer - Free, open source utility to mass rename files, images. Fast, powerful.