Yes, Aptoide is completely legal. Aptoide was founded in 2011 in Lisbon, Portugal, and it's just an open source solution for a completely monopolized market: app distribution. The main goal of Aptoide is to allow users to have an alternative option to discover and download the best Android apps. The company has offices in Lisbon, Shezen (China) and Singapore and offers services the over 300 million users worldwide, along with several OEMs and third-party app stores.
Aptoide offers over a million completely free, and safe apps and it’s currently ranked as the safest app store in the market by an independent research study. All content in Aptoide is either user-generated, which means that it is uploaded by Aptoide users, or provided by the developers that want to distribute their apps to millions of users everywhere. The best part? All apps are thoughtfully scanned to guarantee that not only all the content is completely safe to download and install but it also complies with the corresponding legislation.