Instagram: We have 5M users, nearly 100M photos

Mobile photo startup Instagram is still growing like crazy, according to TechCrunch. The San Francisco-based company says that it now has more than 5 million registered users, that those users add 896,000 photos per day, and that the service will probably crack 100 million total photos sometime this week.

Achieving those numbers after only eight months is particularly impressive. At this point in their history, services like Twitter and Foursquare hadn’t even reached 1 million users. That certainly suggests there’s big potential of mobile photo-sharing (which is presumably why each of the top venture firms has backed a photo startup — Instagram has raised money from Benchmark, Picplz is backed by Andreessen Horowitz, Path has money from Kleiner Perkins Caufield & Byers, and Color famously raised a huge round from Sequoia). And, of course, Instagram’s user numbers also suggest that competitors (who have mostly not released user numbers) will need plenty of momentum if they’re going to catch Instagram.

The TechCrunch post notes another amazing statistic about the company: It still only has four employees. Co-founder Kevin Systrom says that hiring is the top priority, but so far I haven’t seen any of the slow load times or crashes that occur when a company’s growth exceeds its resources.

I’ve emailed Instagram to confirm the numbers and will update if I hear back.