SAN FRANCISCO - Google Inc. stepped up its efforts Wednesday to win over online music fans by launching a streaming music service that competes with services like Pandora and Spotify.

Calling it "radio without rules," Google said its "All Access" service would let users choose from millions of tracks and provide recommended songs and playlists for $9.99 a month.

With the announcement on the opening day of Google's annual I/O software conference, the Mountain View company moved ahead of rivals Apple Inc. and Amazon.com Inc., which are reported to be working on similar subscription music services. All three companies sell digital music online, but have not offered subscription streaming services.

The streaming-music market is growing, according to the research firm eMarketer, which reported that more than 96 million people are expected to stream music from digital devices weekly in the United States this year.

Google also announced some new features for several of its other products as well as a new stand-alone messaging service to compete with upstarts like WhatsApp and Line. Perhaps the most dramatic is an expansion of the voice-activated Google Now service, which provides spoken answers to questions on both mobile gadgets and desktop computers using the Chrome operating system.

The company's struggling social networking service, Google Plus, is also getting a face-lift with a display that shows posts in multiple columns and provides more information on topics that users post about. It also will have tools that automatically sort photos and even combine them into new images after filtering out blurred images, bad lighting, and other problems.

The lengthy keynote presentation otherwise focused on a variety of new programming tools for software developers who want to build games, apps, and other services on Google's Android and Chrome operating systems. Android is the world's most widely used smartphone operating system, while Chrome has become the world's most popular browser, senior vice president Sundar Pichai told an audience of 6,000 programmers, analysts, and tech journalists.

Google did not announce any new laptops or phones.