As a freelancer, you don’t have to fork over expensive commercial software: there are plenty high-quality open source applications and utilities that can help you to run your daily business smoothly. Even if you are new to open source, you are probably already familiar with the usual suspects such as OpenOffice.org, Mozilla Firefox, and Thunderbird. But there are quite a few other useful applications that deserve a place in your freelancer toolbox.

Chandler Described as “the Note-to-Self Organizer”, this application acts as a note aggregator and processor. Notes in Chandler can be turned into tasks, events, and messages, and they can be organized into collections. You can sync your personal information between multiple machines as well as access it using the Chandler Hub service. You can even roll out your own Chandler server, which can come in handy if you need an in-house solution for a small workgroup.

Kimai Keeping track of the time you spend on your project is crucial if you are paid by the hour. Kimai allows you not only to track the time you spend on each project, but also offers powerful reporting capabilities. Kimai is based on the MySQL/PHP stack and runs in your browser. But if you prefer a more traditional desktop solution, you might want to try JWorkSheet

BambooInvoice As a freelancer or small business owner, you have to take care of many things, including invoicing your customers and keeping track of payments. BambooInvoice can help you with that. This MySQL/PHP-based application provides a one-stop solution for generating, sending, and managing invoices.

DokuWiki There are quite a few easy-to-use content management systems and wiki engines out there, but none of them can beat DokuWiki when it comes to flexibility, power, and sheer elegance. DokuWiki doesn’t rely on a database back-end, so it’s easy to install and maintain. But what makes DokuWiki truly unique is an impressive collection of plugins that allow you to extend DokuWiki’s default functionality. Using plugins, you can turn your wiki installation into a blog or calendaring solution, insert charts, embed videos, and much more.

Chyrp While WordPress is probably the most popular blog engine on the Web, it’s not the only fish in the sea. If you are looking for a lightweight blog engine that is both easy to use and flexible, try Chyrp. On the project’s web site, you’ll find a decent selection of themes and extensions to extend Chyrp’s functionality.

TreeLine is an unusual application that combines the features of a traditional outliner with a free-form database. As such, it offers a unique way to organize your stuff, be it contact information, bookmarks, text snippets, bibliography, task lists, or something else. Moreover, using TreeLine’s outlining capabilities you can easily group and manage the mixed data inside the database.

Simple Groupware If you need an all-in-one groupware solution, Simple Groupware should definitely be on your list. Simple Groupware comes with an impressive number of modules, including Calendar, Contacts, Email, Notes, Passwords, Bookmarks, Galleries, Projects, and much more. Better yet, it’s relatively easy to create custom modules using Simple Groupware’s own markup language.

Collabtive If a full-blown groupware solution like Simple Groupware is overkill for your needs, take a look at Collabtive. This lightweight Web-based project management solution offers all the essential features that can help you to keep track of your projects and tasks. Collabtive’s nifty features include a dedicated timetracker, support for milestones, and the ability to attach documents and files to projects.

Jarnal On the face of it, Jarnal looks like a notetaking and sketching application similar to Microsoft OneNote. But Jarnal has a few clever tricks that make it an excellent collaboration and annotation tool. For example, you can use Jarnal to annotate PDF files, and its editing tools put it far ahead of other open source PDF editing tools. Since Jarnal can act as both a server and client, you can use it as a tool for collaborative editing.

TiddlyWiki It wouldn’t be an exaggeration to say that TiddlyWiki is one of the most ingenious tools out there. TiddlyWiki is a notetaking tool which consists of a single self-contained HTML file, so you can use it on any machine with a browser. Unlike other notetaking applications, TiddlyWiki manages notes as containers called tiddlers which you can hide and show at will. This allows you to manage your notes in a non-linear manner.

By Dmitri Popov