With well over 125 million active users a month uTorrent is by far the most used BitTorrent client. Because of its success the software is also the main source of revenue for San Francisco based parent company BitTorrent Inc. It is estimated that the company currently generates between $15 and $20 million in annual revenue but this figure is expected to rise after it was quietly announced that uTorrent will become ad-supported.

uTorrent for Windows saw its first public release in September 2005 and soon became the most widely used BitTorrent application. Today over 125 million users worldwide use the client regularly and this number continues to rise.

After BitTorrent Inc. bought the software in 2006 it evolved heavily. What began as a minimalist and no-nonsense client targeted at a BitTorrent-savvy crowd, is now an application that does far more than downloading alone.

As always, some love the changes and added features while others complain bitterly after every bug fix. However, the announcement that uTorrent will become ad-supported is expected to meet wider resistance among a certain crowd.

The change was quietly made public in a forum post yesterday where it is framed as “a fresh approach to creating a no-nonsense and free torrenting experience.”

After nearly seven years this is the first time that advertisers will be able to reach millions of uTorrent users directly from within the client itself.

Until now nearly all revenue came from the toolbar which users can install optionally when uTorrent is first downloaded. However, BitTorrent Inc. sees the need to experiment with other revenue sources with “sponsored torrents” being added for all users in an upcoming release.

“You are all very familiar with how we have paid the bills so far. These new changes mark our next step towards finding that difficult balance between keeping our lights on and providing a positive user experience,” they explain.

The sponsored torrents will appear in a highly visible spot on top of the list of downloads and will be used to promote content from advertisers. They can’t be “turned off,” but users have the option to click away individual ads.

“This new build will display a featured torrent at the top of your torrent list. This featured torrent space will be used to offer a variety of different types of content. We are working towards bringing you offers that are relevant to you.”

“This means films, games, music, software…basically anything that you will find interesting. We may not get it right on the first try but we will continue to improve our efforts based on your feedback,” BitTorrent Inc. adds.

The company explains that aside from ads the sponsored torrents will also be used to inform users about important updates and to promote artists.

BitTorrent previously informed TorrentFreak that people in different geographical locations will see different content. This means that uTorrent will use your IP-address to lookup where you are. Other than that, the company says that users’ privacy is guaranteed.

For BitTorrent Inc. the main motivation to add sponsored torrents is to generate extra revenue. The company added dozens of employees to its payroll in recent years, and these all have to be compensated.

However, a person close to the company told TorrentFreak that even without the uTorrent ads the company is doing very well. Current annual revenue is estimated at somewhere between $15 and $20 million and the company is backed by millions in venture capital.

With “sponsored torrents” BitTorrent Inc could possibly bring in millions of added revenue and grow even further.

The uTorrent team closed their announcement with a request for feedback, and we would like to do the same. What do you think of uTorrent’s move to add sponsored torrents? Does it put you off or is it no problem in exchange for a free client and service? Let us know in the comment section below.