You can't query a member directly by email address, no. But you can query for the most recent set of members, ask for their email address, and filter through for a match in order to get their id or screenName.
Thanks for the heads up; we have updated the links. Essentially you will need to 1) Create an API key and secret on your test network for your app and then 2) take a look at the section in the documentation…"
No, there's no built in functionality to do this type of thing. We recently added the ability to redirect new members to a custom url, which could be outside of the network and which can include data to let you know their screenName,…"
When you authenticate a member via the API, you get back an author value, which is equivalent to their screenname. You can then make an additonal call to get extra information. Here's some documentation.
You can apply just a width or just a height, and the image will be resized to maintain its aspect ratio. If you want to crop, you can apply a height and width and specify the crop parameter: &crop=1:1
Thanks for reporting this, we will investigate. In terms of pricing, API usage will continue to be free for the next 2 or 3 months, and we'll be updating the language to reflect that soon.
Here's an ultra simple example:
You should be able to prefill the form…"