Some developers who build using Twitter's API (application programming interface) may be a little dismayed today: the company has reportedly stopped “whitelisting” developers to use the API at its most robust level (allowing developers to skip so-called “rate limiting”).

Whitelisting was described by Twitter in this way: “Some applications find that the default limit proves insufficient. Under such circumstances, we offer whitelisting. It is possible to whitelist both user accounts and IP addresses. Each whitelisted entity, whether an account or IP address, is allowed 20,000 requests per hour.”

No longer. Yesterday, on Twitter Development's Google Groups page, a blog post appeared that announced, “ Beginning today, Twitter will no longer grant whitelisting requests. We will continue to allow whitelisting privileges for previously approved applications; however any unanswered requests recently submitted to Twitter will not be granted whitelist access. Twitter whitelisting was originally created as a way to allow developers to request large amounts of data through the REST API. It provided developers with an increase from 150 to 20,000 requests per hour, at a time when the API had few bulk request options and the Streaming API was not yet available. Since then, we've added new, more efficient tools for developers, including lookups, ID lists, authentication and the Streaming API. Instead of whitelisting, developers can use these tools to create applications and integrate with the Twitter platform.”

So, according to Twitter, whitelisting is being discontinued because it's no longer necessary. However, not everyone agrees that this is the reason. SAI Business Insider presented some theories today as to the reasons behind the decision, as follows:

They're having problems scaling so they want to cool down the API for a while. Most of the activity on Twitter is via the API, since most people use Twitter through apps, whether it's Twitter's own apps or third-party apps. Twitter hasn't said that's the reason, but Twitter's scaling difficulties are legendary and this might be the reason. In which case, the move could be temporary, theorized Business Insider.

Twitter has a big enough developer ecosystem now, thank you very much, so it's going to stop supporting the rest. That's what Regular Geek thinks, writing they've "essentially ... decided that they have had enough support from the small developer." We're doubtful that's the explanation -- platforms like Twitter are always in competition with other platforms for developer support. And with oodles of cash in its coffers, Twitter can afford to keep supporting developers.

Maybe Twitter plans to charge for its API? That's always been rumored to be a future business model for Twitter. Right now they're focused on advertising, but the first time they made money was by charging Google and Microsoft for access to its "firehose", meaning all of the tweets in real time, and they still do that. As companies like TweetDeck are starting to build a real business, maybe Twitter wants to charge for heavier access to its API.

So what do you do if you're a developer looking for the kind of escalated access that was formerly granted by whitelisting? Live with it, says Twitter on the Google Group page. “We also want to acknowledge that there are going to be some things that developers want to do that just aren’t supported by the platform,” notes the blog. “Rather than granting additional privileges to accommodate those requests, we encourage developers to focus on what's possible within the rich variety of integration options already provided.”