@cynicalgrinch For Cards there are no limits and no paid plan.
We do offer Branded Cards at a paid plan. These are customizations to the standard cards to make them unique. For example, we power Airbnb's embeds:
https://www.airbnb.com/rooms/50724 (click embed this listing under "Save To Wish List" )
As well as StockTwits:
http://stocktwits.com/howardlind... (click on embed on the right)
Because this community is interested in early stage product design and iteration, here is a bit of information on how Cards came to be.
Cards were initially created to solve a pain point. We would get support tickets from people who wanted to create embeds, but were not developers. So we made a simple 'get embed code' in our embed explorer. This was something like three levels deep in the site, and when it gained traffic, we moved it to the front with a more prominent link: embed.ly/code. When this gained more usage, we took some time to style the embeds and make them responsive. We prototype a lot, and when the data reveals a promising idea, we move forward.
Fun challenges to work through in the design:
1) How to balance the branding of the page posting a Card, the content of the Card itself, and Embedly. Ex. Huffpo posts a Vine card.
2) How to make the embed work well in a variety of contexts and not look like an ad. The first prototypes felt out of place, and like ads.
The most significant changes we have made since the initial release have been simplifying the action buttons in the top right, introducing more minimal design options, and testing out new product features like recommend and analytics.
For the most part growth has been through http://embed.ly/code. Some sites dug into the code and built hard integrations into their sites/CMS. While Cards were initially targeting writers/bloggers, we found developers were thrilled to use them since styling was handled out of the box. For developers interested in programmatically using cards: http://embed.ly/docs/products/cards. Integration is as simple as including a script and adding a class to a link. Here is a fiddle showing this: http://jsfiddle.net/kewfq9ru/
Some numbers: last month 42M Cards were served across 11K domains.
Idea Stash