SAN FRANCISCO — It has taken years, but Google Inc. seems to be cutting into Microsoft Corp.’s stronghold — businesses.

Google’s software for businesses, Google Apps, consists of applications for document writing, collaboration, and text and video communications — all cloud-based, so that none of the software is on an office worker’s computer. Google has been promoting the idea for more than six years, and it seemed that it was going to appeal mostly to small businesses and tech start-ups.