Google Adds Billing to App Engine

Google announced Feb. 24 that the company has added billing to the Google App Engine cloud computing platform so developers can exceed the free usage quotas that have been in place. Google also said it will soon be reducing, but not eliminating, the free quotas.

With the new billing capability, "developers can now purchase additional computing resources on App Engine, enabling apps to scale beyond our free quotas," Brett Slatkin, a member of the Google App Engine team, wrote in a blog post. "This has been our most requested improvement to App Engine and we're thrilled to deliver it, as promised."

When Google delivered App Engine in April 2008 it was free, albeit with usage quotas. And although the quotas remain, developers will now be able to pay to exceed those quotas. Slatkin said developers will have to "pay for only what your app consumes beyond the free thresholds—prorated up to the nearest penny."

App Engine remains free to get started, Slatkin said. "However, along with many performance improvements over the past 10 months, we've learned that we overestimated our initial free quota values," he said. "Therefore, in 90 days we will be reducing the free quota resources. We believe these new levels will continue to support a reasonably efficient application serving around 5 million page views per month, completely free."

The new free quota levels, which will take effect on May 25, 2009, are:

CPU Time: 6.5 hours of CPU time per day

Bandwidth: 1 Gigabyte of data transferred in and out of the application per day

Stored Data & Email Recipients: these quotas will remain unchanged

The pricing for resources beyond those free quotas is:

$0.10 per CPU core hour. This covers the actual CPU time an application uses to process a given request, as well as the CPU used for any Datastore usage.

$0.10 per GB bandwidth incoming, $0.12 per GB bandwidth outgoing. This covers traffic directly to/from users, traffic between the app and any external servers accessed using the URLFetch API, and data sent via the Email API.

$0.15 per GB of data stored by the application per month.

$0.0001 per email recipient for emails sent by the application

"Data in the datastore incurs additional overhead," and users may "notice an increase in the amount of data stored by your application that is listed in the Admin Console," Slatkin said.

"To decrease the impact of this change … we've doubled the free storage quota to 1GB," Slatkin said.