Why I built it
For iOS, it's still hard to install an app you found while browsing on your desktop computer. There are services that text you the app link, but everyone has email on their smartphones, so why not just email them the link? It's easier and free.
I couldn't find a free service for this, so I built something using Google Apps Script as "Get The App Link" email service for my app.
How it works
You write an Apps Script to 1) capture the visitor's email address, 2) dispatch the app link email using Gmail Service to the email address, and 3) log the email address to Google Spreadsheet. Deploy the script as web app. Embed it on your site and add some front-end notifications. Now you have your own free email sending service :)
Let me know what you think or if you have questions!