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Selling on Happy Size

Happy Size is a German webshop for plus-size fashion. Since July 2025, Happy Size runs a marketplace on Mirakl in Germany and Austria. The marketplace is active in Germany and Austria.

Happy Size runs on Mirakl, so you connect it with the Mirakl integration. This page covers what is specific to Happy Size; the Mirakl setup guide describes every field in detail.

1. Get access to Happy Size​

You apply as a seller with Happy Size. Once approved, you create the API key in the seller back office.

2. Create your API key​

  1. In the Happy Size seller back office, click on your name in the top right corner and open your user settings.
  2. Open the API Key tab, generate a key and copy it.

3. Connect Happy Size in StoreLinkr​

  1. Navigate to Sales Channels -> Marketplaces and click Connect a marketplace.
  2. Click the Happy Size tile. Use the search field or the country filter to find it quickly.
  3. Paste the web address of the seller back office as the marketplace URL, for example the address you see after logging in. A full address including /login is fine.
  4. Paste your API Key, choose the Country, the Product Selection and the Pricelist.
  5. Click Test connections and then Connect a marketplace.

Good to know​

  • Who can sell: Happy Size does not publish who may sell on its marketplace or how to apply, so sellers should contact Happy Size to find out.
  • Products are offered on the Happy Size catalog by EAN. Products without an EAN, or that are not in the Happy Size catalog yet, are not listed.
  • New Happy Size orders are accepted automatically and imported once Happy Size releases the delivery address. Tracking codes go back to Happy Size when you ship.
  • Selling on several Mirakl marketplaces? Connect each one separately, each with its own API key, product selection and pricelist.