I have structured data for SoftwareApplication in HTML page like this:
https://developers.google.com/structured-data/rich-snippets/sw-app
But if I check my structured-data: https://developers.google.com/structured-data/testing-tool/
Its have warning: offers: missing and recommended
My Android application is free. How can I write this for free App?
<div itemprop="offers" itemscope itemtype="http://schema.org/Offer">
Price: $<span itemprop="price">1.00</span>
<meta itemprop="priceCurrency" content="USD" />
</div>
For the Offer, a price of $0 is valid and what Google SDT expects in this case.
<div itemprop="offers" itemscope itemtype="http://schema.org/Offer">
Price: $<span itemprop="price">0.00</span>
<meta itemprop="priceCurrency" content="USD" />
</div>
If you don't want to show the price, you can use meta tag again for price.
<div itemprop="offers" itemscope itemtype="http://schema.org/Offer">
<meta itemprop="price" content="0.00" />
<meta itemprop="priceCurrency" content="USD" />
</div>
In general though, Google wants you to show the price to the user since it might create misleading or deceptive search experience. See policy: https://developers.google.com/structured-data/policies#non-visible_content_and_machine-readable_alternative