Are there Magento API to import massive external data (products) from a third-party application into Magento database programmatically? If they exist, what are they and how can I find them? Since I am a beginner to Magento, would you please be so Kind to give me detailed information? Thanks in advance
Magento comes with a SOAP and REST API out of the box.
Magento SOAP API: https://www.magentocommerce.com/api/soap/introduction.html
Magento REST API: http://devdocs.magento.com/guides/m1x/api/rest/introduction.html
The REST API does not offer as much functions as the SOAP API so you need to have a look what functions you need.