LOS ANGELES -- Google (GOOG) is turning on a "scan and match" service for Google Music users to store copies of their songs online, offering for free a service for which Apple (AAPL) charges $25 a year.

The service, which launched Tuesday, cuts uploading time for those who want to save their music libraries online. It scans a user's computer and gives them online access to the songs it finds, as long as they match the songs on its servers. Otherwise, it will upload songs to a user's online locker.

The service is similar to Apple's iTunes Match, which includes online storage for 25,000 songs. Google allows storage for 20,000 songs and allows users to re-download the songs only at the same quality as they were at previously. Apple upgrades songs to iTunes quality.

Amazon runs a similar matching and uploading service called Cloud Player. It costs $25 a year for 250,000 songs. A free version is limited to 250 songs.

Google is still a fledgling entrant into music sales since debuting its store in November 2011, though it expects to benefit from the hundreds of millions of devices that use its Android operating system on mobile devices.

According to the NPD Group, Apple accounted for 64 percent of U.S. music sales online, followed by Amazon at 16 percent. Google has no more than 5 percent, according to NPD. Other services make up the rest.

Google had sold songs at a discount at the start, but that is less so the case now. For example, it was selling the top-ranked Bruno Mars song "Locked Out of Heaven" for $1.29 on Wednesday, the same as iTunes, and above the 99 cents on Amazon. But its album price was lower at $10.49 versus $10.99 at both iTunes and Amazon.