Google offered some details about its plan to rate-limit the Google Maps API in a statement posted yesterday on the company’s Geo Developers blog. Developers who exceed the rate limits will have to either pay overage fees or buy a Maps API Premier subscription.

According to the blog post, Google will wait until next year before it actually starts enforcing the new rate limits. The delay is to give developers some time to adjust to the change and make appropriate preparations. The new rate limits will pose an unfortunate barrier to ubiquitous map mashups on the Internet, but the pricing model will help make the service more financially sustainable, ensuring that Google doesn't have to shut down free access entirely.

“We understand that the introduction of these limits may be concerning. However with the continued growth in adoption of the Maps API we need to secure its long term future by ensuring that even when used by the highest volume for-profit sites, the service remains viable,” wrote Google Maps API manager Thor Mitchell. “By introducing these limits we are ensuring that Google can continue to offer the Maps API for free to the vast majority of developers for many years to come.”

The terms of use for the Google Maps APIs have always been a bit restrictive, possibly because of the complexity of the licensing terms behind the data and images. When I first started experimenting with the APIs two years ago, I ended up using OpenStreetMap instead because Google’s terms of service entirely prohibited embedding Google Maps in desktop applications. They have since partially eased up on restrictions of that nature.

Google originally announced plans to impose rate limiting on the Maps APIs back in April. At the time, the company explained that they would have to impose fees on heavy commercial users in order to be able to continue offering the APIs. The latest announcement offers some clarification and technical details. Google is going to add tools to its API console so that developers can more easily track their Maps API usage. Google is also encouraging developers to configure payment options now, with the promise that they won’t be billed until the limits are enforced next year.

The upcoming pricing structure is laid out in the Google Maps API FAQ. Most developers who use version 3 of the JavaScript API or the static maps API will be capped at 25,000 map loads per day. They will be expected to pay a fee of $4 per thousand loads in excess of the limit. The cap is set to 2,500 loads for styled maps that customize the presentation. After 25,000 loads, the overage fee for styled maps will bump up to $8 per thousand.

Google says that especially heavy users will probably be better off buying a Maps API Premier subscription rather than paying the overage fees. The company has also indicated that they are willing to make special accommodations for non-profit organizations on a case-by-case basis.

Google’s approach to enforcement will likely not be very aggressive. According to the FAQ, sites that hit the rate limit and aren’t configured to pay overage fees will not immediately be cut off. This suggests that sites with an occasional traffic spike aren’t the intended target—Google is mainly looking to collect cash from sites with a consistently heavy load.

Listing image by Illustration by XKCD