And perhaps the concerns are legitimate. Will Facebook's questionable privacy policies be transferred to Instagram? What will Facebook do with any new personal information it acquires from buying Instagram's user database? And what will Facebook do, if anything, to Instagram's user interface?
Don't worry, says Facebook founder Mark Zuckerberg.
"We believe these are different experiences that complement each other," he wrote in a Facebook posting announcing the acquisition. "That's why we're committed to building and growing Instagram independently. Millions of people around the world love the Instagram app and the brand associated with it, and our goal is to help spread this app and brand to even more people."
Despite that, some of Instagram's 30 million users have declared they'll drop their accounts and move on. If you're one of them, where can you go next? There are other mobile apps and services that replicate Instagram's photo-sharing features, from altering their look with filters to sharing them with friends on social networking services.
If you're looking for an Instagram alternative, here are some popular choices.
Pixlr-o-matic (iPhone, Android, free) • This photo app, like Instagram, allows you to apply different filters to your snapshots to give them a hip or retro look. The developers claim you can make as many as 2 million different finishes for your photos.
Hipstamatic (iPhone, $1.99) • A popular app among photo buffs, this camera app gives you the control and feel of analog cameras. It lets you change the look by virtually swapping lenses, flashes and types of film. For an extra cost, you can buy and download add-ons that simulate the look of certain cameras and lenses.
picplz (iPhone, Android, free) • The different photo effects are more limited with this app, including such effects described as only "Russian toy camera" or "Little Plastic Lens." But it does have a photo-sharing service where you can upload your finished pictures.
Hipster (iPhone, Android, free) • Like Instagram, you can alter photos with a variety of effects and tag friends in the photos. But you also can create virtual postcards from the photos and add your own text before uploading them to a variety of social networks.
ShakeItPhoto (iPhone, $1.99) • Perhaps more novelty than actually useful, this app takes retro photography to new heights. ShakeItPhoto re-creates the Polaroid experience. The picture appears on your phone like a Polaroid photo, and you can even shake your device to make the image appear faster (not that shaking the real Polaroid picture ever developed it faster). Its sharing function is more limited, only letting you email the picture or post it on Facebook directly.
PicYou (iPhone, free) • The makers of this app claim it has been downloaded more than 500,000 times in three months. The free version comes with a number of photo effects that you can apply after the picture's taken as well as different frames. Those photos can then be saved in a cloud-based service provided by PicYou as well as sent to Twitter or Facebook.
Lightbox Photos (Android, free) • It has all the requisite photo effects, but Lightbox's emphasis is in its social networking. This app allows you to post your photos to their site, where you can create your own photo blog. You also can interact with your friends and others in the Lightbox community by seeing streams of their photos.
Streamzoo (iPhone, Android, free) • This photo app includes 14 filters to change the look of your pictures, but what sets it apart from the rest is it then turns the sharing of your photos into a kind of game. Once you upload your photo to Streamzoo's service, you can then earn badges and points the more your photos gets likes on the site.
email@example.comGoogle+: +Vincent Horiuchi