Yesterday, American Express announced it would be partnering with Twitter to enable a tweet-to-pay feature. This means after syncing your Amex card, all you have to do it use specific hashtags to buy and order certain items. It’s just the latest partnership between Twitter and Amex, which have been working together for awhile now to bring payment services to the platform. In March of last year, Amex introduced a hashtag-to-save program, a tiptoe into the more fully-fledged service it’s now launched.

But as is generally the case with Twitter features, tweet-to-pay is sort of old news – thanks to third party developers. A handful of outside apps have been paving the way to making Twitter a true e-commerce platform long before the limited, daily-deals-like announcement from the microblog and American Express – chief among them being Chirpify.

Chirpify launched over a year ago as a service for brands to enable Twitter payments for their customers. The platform allows you to use card or PayPal and has features like peer-to-peer payments and charitable giving built in. Various partnerships have helped increase its visibility as well: Green Day has used Chirpify to sell music, and writer David Wolman used the service to sell his book. Chirpify has the same setup going with Instagram, too, so cross-platform compatibility has begun.

Founder and CEO Chris Teso tells me that Amex Ventures actually approached Chirpify early on about investing but decided against it because Amex Business said the startup was “competition” – a ringing endorsement in Teso’s eyes. “We’ve seen this coming for awhile,” he says of the Amex-Twitter tweet-to-pay solution. “It’s a good thing when Amex considers your startup ‘competition.’”

The concept of using Twitter as a payment platform goes even further back. In 2010, Pay with a Tweet launched to combine the value of social media promotion and easy payments. While Pay with a Tweet actually doesn’t involve money currency as we know it, it’s selling leverage: People producing digital content use the button to put a pay wall around the material, and users can access it by tweeting about it – thus creating some buzz (hopefully). It’s part of Twitter/Amex’s and Chirpify’s systems – the idea of simultaneously getting access to something while also spreading a little word about it.

“Pay with a Tweet uses the network [Twitter] as currency,” creator Leif Abraham says. “So exposure becomes the money.”

“Our system is doing very well and is constantly growing with more than 3.5 million Pay with a Tweet transactions to date.” Application updates are on the way as well, and Abraham says the next iteration will roll out shortly.

At the moment, what Twitter and Amex have launched seems like more of an experiment than anything else. What you can buy is limited, and you clearly have to have an American Express card – something that stands to hold Twitter back if it plans to truly turn in-house to create a payment system. Developing for Twitter remains a risky move. The social network has made a reputation for itself as a less than gracious host to outside developers, and any move into the e-commerce space might feel like a warning to interested parties. But more than anything, it seems like the launch is more about Amex expanding its digital compatibility, and good for them – still, Twitter has a long way to go (and new partnerships to forge) before it can compete with what outside platforms have been able to accomplish using its network.