How do I integrate Willhaben.at + Shöpping.at + Universal.at marketplace feeds?

Austria’s top three local marketplaces, combined they reach the vast majority of Austrian online shoppers:

• Willhaben.at, Austria’s eBay + classifieds hybrid, >3M monthly users, market leader. Both C2C and B2C (Willhaben Marketplace + Willhaben Shop). Magento feed via Willhaben’s XML / CSV product feed spec.
• Shöpping.at, Österreichische Post’s marketplace, AT-focused, ~10k merchants. Magento integration via REST API (Shöpping Connect) or XML feed.
• Universal.at, Otto Group’s Austrian marketplace, fashion / lifestyle / home. Feed via the Otto Marketplace Connector.

For Magento we install a marketplace-feed module (M2E Pro, ChannelPilot, or custom) that:

1. Maps Magento catalog_product attributes to each marketplace’s required spec (some demand specific category trees, condition fields, EAN).
2. Pushes price + stock updates every 15-30 min so over-selling is rare.
3. Pulls orders back into Magento as native orders with marketplace channel metadata.
4. Handles per-marketplace fees + commission accounting (Willhaben takes ~5-9%, Shöpping ~7-12%).