It’s convenient to build apps using 3rd party APIs, but it’s also dangerous to build business on them. Especially if you’re using APIs from Facebook and Twitter.

App developers who helped make Twitter more useful and accessible to got their first kick in the groin Twitter bought Tweetie iPhone app in April 2010. At that point, any company in the mobile Twitter client business was toast. About a year later, Twitter bought Tweetdeck and told developers to not “build client apps that mimic or reproduce the mainstream Twitter consumer client experience.” Now, desktop/webtop apps were toast too.

This was the beginning of the end of a cottage industry of innovative 3rd party apps that had helped Twitter become accessible, popular and more complete. Since then, Twitter has constantly changed the definition of “the mainstream Twitter consumer client experience” as it picks up successful ideas from 3rd parties and then takes measures to squeeze those apps out of the market.

The latest example of this is Twitter’s plans to create richer, magazine-like experiences via expanded tweets, inspired by apps like Flipboard, Instagram and YouTube. This richness can only be experienced at twitter.com and cannot be replicated by companies like Flipboard, who will only be allowed to peddle 140 characters or less of text.

3rd party developers are invited to the party again, this time to help create content for these ‘richer’ units on twitter.com. (When I say developers, I mean content publishers. App developers are running for the hills).

It seems that Twitter is taking a cue from Facebook, which successfully convinced brands and publishers that it was better (or at least critical) to set up shop inside of Facebook and treat your owned media properties as of secondary importance. I have no doubt that media companies would jump onboard – and I can’t blame them. It makes business sense for both publishers and Twitter.

However, for app developers there are lessons to be learned.

I become cognizant of the dangers of building on top of Twitter after my business partner and I built the “Realtime Pro Football” iPhone app in 2009 and Twitter shortly thereafter started going after apps that mimicked the Twitter user experience. While Twitter had yet to object (and probably wouldn’t have), I decided it was too risky to continue down this path.

Facebook felt like a safer place. When I launched “Open Audience Manager” in September of 2010 I felt more confident that I wasn’t building my house on sand. This product was an enterprise Analytics and Engagement platform for Facebook’s Open Graph. It helped online retailers make every product in their catalog an Open Graph object, and as such offered Facebook insights data at the product level, not just for a brand’s Facebook Page. Additionally, it made it possible to use Facebook’s communications channels to start a dialogue with Friends of each product – about that specific product, driving them through the purchase funnel. The product generated unprecedented ROI for the F100 clients that used it. Until now. Facebook just announced that they are removing the ability to publish messages to Friends of Open Graph web objects. They basically removed a key part of the value proposition of the Open Graph: Open Graph Objects can live anywhere, sharing a common set of bonds and communications channels with its Friends.

The problem with both Facebook and Twitter is that they haven’t completely figured out the role of 3rd party developers. They may say they embrace the development community, but they don’t really respect the community. Companies like Salesforce and Google have figured this out, mostly because they are committed to helping 3rd party developers make money as a way for themselves to make money.

That said, while 3rd party developers may be disappointed, this is not really a criticism of Facebook or Twitter as businesses. They need to maximize their revenue. A long as developers understand that Facebook and Twitter aren’t true development platforms, there is nothing wrong with building products and services that leverage Facebook and Twitter. I urge 3rd party developers to do so.

If you want to be part of the social media revolution, you can’t do it from the sidelines. You have to make your bets and take calculated risks that something that you rely on may be here today but gone tomorrow.

Good luck.