Scott Blomquist

You no longer have to live in fear of the day that your application built on Google’s App Engine (GAE) actually becomes successful. Until now, if your application exceeded its daily quotas, your users would simply be turned away.

You had no option to migrate off of GAE because of its completely custom execution environment that is almost impossible to duplicate outside Google, and you had no option to purchase additional resources to keep your application running above and beyond the resources that Google was willing to give to you for free.

Google just announced that this has changed. You can now buy resources such as CPU time, bandwidth, storage, or emails if the popularity of your application causes you to exceed the quotas imposed on freeloaders.

I still have some big concerns about choosing Google App Engine as the hosting environment for a real business application:

1. Despite attempts at replicating App Engine elsewhere, you still have no good migration path away from GAE if you ever discover a reason to do so.
2. If you build a startup on App Engine, post-acquisition integration will be difficult unless you were acquired by Google.
3. There are still built-in limits on your success—notice the “Billing Enabled Quota” numbers that are posted on App Engine’s Quotas page. You have to make a special request to Google to exceed these. Maybe they’ll say yes to every request they ever get. Maybe they won’t.

The bottom line is that the new billing model probably makes Google App Engine good enough now for nearly any casual web services project, but if you’re looking to build a commercial web service that you can scale to the stars, you’d still be better off considering a hosting environment such as Amazon Web Services where you have total control over the environment in which your application runs, and could migrate elsewhere (including your own data center, or that of your acquirer) should the need arise.