If you ever have to import and data into a Magento ecommerce store, Magmi is your go-to tool.
Whatever you do, don’t try to use the native Magento importer, it will waste hours of time and will raise your stress levels. Go directly here (https://sourceforge.net/projects/magmi/), get the download and prepare to start saving yourself some time.
Sure, the prepare part is going to hurt a little, mainly because the documentation is dense, something it needs to be because of the many useful functions Magmi can perform for you.
The project is developed privately by Seb Bracquemont AKA dweeves.
We use Magmi for bulk imports, SEO tasks and most importantly for the import of configurable products. It has many other uses for example, you can upload and update a batch of new product images with a simple spreadsheet that has two columns; SKU and image name.
Here are some of the features as listed on the Magmi SourceForge page.
For us the most useful feature of Magmi is its simplification of the creation of configurable products. You can find out more about setting up Magento for configurable products here: Magento Configuarble Products Made Easy
To download and install Magmi – here is the place to go: https://sourceforge.net/p/magmi/
For a guide about how to troubleshoot MAGMI import errors click here.