AngelList has announced that 3 million requests each day are being processed through its API. The needs of the service are said to be coming from its more than 50 partners, incubators, and others.

Started as a side project by “venture hacker” Josh Slayton, AngelList’s API has been a favorite for groups like SecondMarket and 500 Startups. It’s first customer was Rapportive, which brought AngelList profile information for contacts right into Gmail.

AngelList says that there are more than 50 companies using the service, of which they all use the AngelList OAuth protocol. Some of the 3 million API requests come not only from Rapportive, but also from Engagio, StartupDataTrends, Pocket Angel, AngelList Wings, and more.

Incubators and accelerators are also getting in the game. Last Fall, 500 Startups used AngelList’s API in its application process for its newest batch of accelerator companies. This month, Launchpad LA began using it to accept applicants for its program.

SendGrid, who use it to help identify its high-value customers, and venture capital firms are also customers of the API. It’s not surprising that VC firms are using the service as Naval Ravikant, AngelList’s founder, said that 30% of investments come from VCs.

What are people using AngelList’s API for? The company says that a variety of tools are being created, including iPhone and Android apps, services that help to visualize the world of fundraising, automate their startup’s AngelList profile, and more. Recently, Angel5, started by Wittlebee founder Sean Percival, became the latest service built off of the API — the idea was to provide a list of investors on the site segmented by market, region, or any number of factors.

The company has been pretty productive in helping startups since its creation. In December, it announced that it had helped raise over $12 million for companies over the past 30 days right through its network, both from online and offline means. Today, if you look at AngelList’s website, now more than $14 million has been raised in the past 30 days and more than 2,600 introductions have occurred.

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