Dimdim is an open source alternative to proprietary web conferencing packages like WebEx and GoToMeeting. We first wrote about them back in September 2006 when they were offering an alpha version of their on-premise solution.

Today the company is releasing a hosted version of that solution that requires no setup to use - not even a browser plugin like other offerings. CEO DD Ganguly says by getting rid of plugins, Dimdim will be more accessible to those who are either technically unsavvy or wary of installing 3rd-party software online.

The hosted web conferencing experience has the same functionality as the on-premise one, except that companies can’t customize it to look like their websites. Dimdim can be used to run slideshow presentations, hold collaborative freehand drawing sessions, chat (in groups or privately), and share desktops.

The free version of the product allows for up to 20 simultaneous users and is supported by advertisements. To get rid of the ads and access benefits like technical support, guaranteed uptime, and custom branding, organizations will have to pay anywhere from $100 to $500 depending on the seats they need.

Dimdim says that its on-premise solution has been downloaded over 200,000 times in 165 countries. About 26,000 people have beta tested this hosted solution.

The open source strategy followed by Dimdim makes most sense when customers want to manage the software on-premise, and it’s not so important when everything’s hosted in the cloud. But it’s good to see competition nipping at the heals of giant WebEx.

Conference calls can be a pain, and getting charged by the minute doesn’t help. But these days, there’s really no reason to pay for them. There’s FreeConfereceCall.com, FreeConference.com, Lypp, and a bunch of other small startups giving away the service.

But while there’s no difference in the cost, Rondee’s Evite-like web interface makes it the simplest conference calling system I’ve seen. The service lets you schedule calls with several little features that make it easier to use.

All you need to do is pick a date, fill out an invitation, and Rondee will email the participants with the number and a pin. Like Evite you can pick a theme, participants can invite others, times can be readjusted by participants, and the service sends an email reminder of the meeting. You can also add meetings to your Outlook calendar in one click.

Participants call into 619-2-RONDEE (619-276-6333) and enter a PIN number (You can pick your own). If you give Rondee your phone number, it automatically logs you in to your conference when you call. Rondee remembers your previous calls and contacts for future reference. Soon they’ll be adding free call recording.

Rondee has plans for putting premium services on top of the platform, such as transcription or WebEx-like screen casting. Competition is fierce, though, with a lot of startups looking to make Cisco regret that $3.2 billion they paid for WebEx. DimDim, Zoho, SightSpeed, Vyew, and Google (acquired Marratech) are all nibbling at their customer base.

Open source startup DimDim has released an alpha version of their new browser based web conferencing software. Users download the open source free code and install it on their own servers. The current version supports IE on Windows only for presenters, which is really unfortunate, but attendees can be in conference via Firefox on Mac. No software download is required for attendees. Future versions will fully support Firefox on Mac, Linux and Windows. If the software ends up solid then DimDim could pose an interesting challenge to the current list of paid, hosted web conferencing solutions.

I tested a version hosted on the DimDim servers early this week and it worked well. Presenters can share their whole desktop or just a single application at a time with attendees. Audio and video transmission is one way from presenter to attendees, from a Flash box in the sidebar. Attendees chat with each other and the presenter.

Resolution on the shared screen isn’t all I wish it was but lag time was very low. There are any number of features that could be added and a hosted alpha will be launched late this year or early next year.

DimDim says that just like Hotmail made free email common and Skype created the expectation that VOIP should be free - they want to make web conferencing freely accessible. The company says that this version is for technically adept early adopters, so if that’s you then now may be a good time to check out DimDim.

Typical of open source companies, DimDim’s business model is based on providing paid support and custom installations for business users. This is a very ambitious project, and even this alpha launch has seen several delays so far - but if it works well then I expect DimDim to be widely appreciated.