Startup Idea: Multiplatform E-commerce Posting Software

Startup idea to develop a software or app that will allow sellers to post their products on multiple online platforms simultaneously, increasing efficiency in the sales process and reducing the repetition of manual posting across different e-commerce platforms.

I sell on multiple online sites and apps and am sick of having to post items over and over and over again. I wish that there were some sort of software or app that could post across all of these multiple sites and apps all at once. There are some sites such as ebay, bonanza and etsy that allow it which is great, but in my case, those are only three of the dozen places in which I need to do so.