Google Play has an undeserved reputation as platform that doesn’t monetize — at least according to several developers with free-to-play games. Companies as diverse as TinyCo, Spry Fox and Robot Invader are seeing Google Play revenues comparable to, and sometimes even higher than, their iOS earnings.

Google Play’s supposed difficulty in generating revenue has been well publicized. According to recent studies from Distimo and Flurry, Google Play earns one eighth the daily revenue of Apple’s iTunes App Store and generates just 23 percent of the average revenue per user (ARPU). Because Distimo and Flurry’s findings are based on broad averages, however, not every developer agrees with their reports.

Spry Fox’s CEO David Edery recently took to Twitter to set the record straight about Android earnings. According to Edery, for every dollar the popular puzzle game Triple Town earns on iOS, the Android version brings in 67 cents. It’s also not a matter of having a much larger, but less lucrative overall userbase on Android — Edery tells us that Triple Town’s Android and iOS userbases are almost exactly the same size and have similar conversion rates. Although the game does return slightly higher ARPU on iTunes than on Google Play, Edery is still bullish on the platform as a whole, calling Google Play, “a very good source of revenue.”

Larger developers are also finding Google Play has plenty of paying users. Andreessen Horowitz-backed TinyCo released figures showing for every dollar its free-to-play game Tiny Village generates on iOS, it earns 65 cents on Google Play. Removing tablets from the equation, the number rises to 82 cents on the dollar. Overall, TinyCo’s Android earnings are much closer to Spry Fox’s than they are to what Flurry estimates the average Google Play ARPU is.

Glu Mobile is another company reporting Android revenues higher than analyst estimates. Although only 30 percent of Glu’s total free-to-play smartphone revenues in the fourth quarter of 2011 came from Android, both platforms deliver a similar ARPU according to the company’s SVP of sales and marketing, Adam Flanders. Glu is also seeing its Android conversion rate continually improve, something Flanders credits to Google Play bringing in more credit card through its store-wide sales and Google Check Out’s expansion of international carrier billing options.

Access to carrier billing is an important tool for Android developers with free-to-play games because it allows users without credit cards to purchase digital goods, boosting conversion and monetization rates. Carrier billing is one of the key reasons companies like DeNA are able to see conversion rates of up to 15 percent in Japan, compared to about 2 percent in North America. The lucrative South Korean market is also the result of carrier billing — Com2uS has a 10 percent conversion rate for its Android games in South Korea and a three percent conversion rate in the U.S.

Robot Invader’s game Wind-Up Knight makes 60 percent of its total revenue through Google Play, largely thanks to carrier billing according to company co-founder (and former Android developer advocate) Chris Pruett. Wind-Up Knight players are also twice as likely to monetize on Android than they are on iOS and when they do convert, Android users generate higher ARPU than iOS ones — once again, largely due to carrier billing.

“Android actually has a number of unique features that make it pretty profitable,” he explains. “One major feature is integration with carrier billing systems across the world.  In some regions (particularly Japan and parts of Europe), nobody buys anything on their phone with credit cards — they all want their purchases to get charged to their mobile phone account and show up on their bill at the end of the month.”

Overall, the story from developers both big and small is that there is money to be earned on Google Play, but the companies that are making the best use of the market aren’t paid apps, they’re free-to-play games that are able to tap into carrier billing internationally.