Important note: Oberlo app has been shut down and is no longer available on the Shopify App Store.
If you consider starting a dropshipping business or add dropshipping products to your existing store, Oberlo will make the main job for you. Owned by Shopify, the Oberlo app allows you to import dropshipping products and start selling the same day, without having to pay for anything upfront. All the information about the products—title, product description, pictures, stock availability—will be copied and transferred from suppliers to your Shopify Store. You can then edit all the data manually from your store admin.
With Oberlo, you have access to millions of products, which you can add to your store and start making a profit immediately.
You might be limited if you want to dropship from other suppliers which aren't located on AliExpress. Oberlo only supports dropshipping from AliExpress, which has, on the other hand, plenty of vendors and fulfillment centers around the world.
Oberlo has two plans available. Explorer is completely free: you can use it to get familiar with the app and import up to 500 products. The second plan is called Boss: for $29.99 per month, it allows you to import up to 30,000 products, proceed a bulk ordering, track shipment, and add multiple staff accounts.