Apple has seeded and released OS X Mavericks Gold Master (GM) to developers for testing. The GM release indicates that a Mavericks launch is near, and this build will most likely be what is released to the public (bearing any major bugs). We expect to see an OS X Mavericks public retail release sometime in the last two weeks of October.
If you are searching for download OS X 10.9 Mavericks GM you are on right place.
Direct link to App Store OS X 10.9