We see significant increase in our user base ... overall we have to say we are satisfied, Opera co-founder Jon von Tetzchner said at the Reuters Global Technology Summit in Paris on Thursday.
Opera is the fourth-largest browser in Europe after Microsoft's Internet Explorer, Mozilla's Firefox and Google's Chrome.
Last December, European Union regulators accepted Microsoft's pledge to give consumers better access to rival browsers, ending a long antitrust dispute.
Since the start of March, Microsoft has been offering Europeans the option to select from among 12 browsers on the more than 100 million old and new PCs that use its Windows software.
Opera, whose wireless browser is the most widely used globally, launched its own iPhone browser last month -- the first rival maker to get access to iPhone -- and said it would also likely customize its browser for Apple's iPad.
It's natural for us to be there, von Tetzchner said.
Nokia, which has so far used Opera's browser on its mid-range phones, bought Opera's U.S. rival Novarra earlier this year, raising fears the Finnish handset giant could stop using Opera on its phones.
Von Tetzchner said the two offerings were different enough for Opera to continue to work with Nokia.
Opera has made two smaller acquisitions recently, but von Tetzchner said the company was focusing on organic growth and that there were no plans for a spending spree.
I am not sure how many companies we will buy, if any, he said.
(Editing by James Regan)