Some of Instagram's 30 million are threatening to delete their accounts after Mark Zuckerberg announced Facebook would purchase the popular photo app for smartphones, complaining of potential privacy issues or that it just "wouldn't be the same."

If you're one of those users trying to replace Instagram as your favourite free photo-sharing app, there are dozens of Android and iOS options with roughly the same features. Like Instagram, many of these apps allow users to edit their photos with various effects, tools, and filters, view photos posted by other users, and share photos on social networks like Facebook, Twitter, and Tumblr.

However, the bottom line is, the right replacement depends on what you liked about Instagram -- the editing tools or the sharing capabilities.

Here are five photo-sharing apps for Android or iOS (they're all free):

Photo editing

If you love applying filters with an old-school feel, editing tools, and other effects to your photos to show the world just how unique you are, here are two apps for you:

1. Pixlr-o-matic

Platforms: iOS, Android

While it doesn't have traditional editing tools like a crop or rotate option, Pixlr-o-Matic has a whopping 68 filters, 73 lighting effects, and 193 borders. Users can upload edited photos to social networks or to imm.io to create a quick link. Pixlr-o-matic's website is also a plus, where users can find all the same features as the app.

2. Snapster

Platforms: iOS, Android

The free version of the app comes with 33 filters and 9 frames. Users who purchase the $2.99 version (Snapster+) will get additional filters, frames, and textures. The preset filters are the same as those offered by other apps. What's different is Snapster allows users to customize and save new filters by applying colour textures and adjusting curves and brightness to existing filters or creating entirely new ones. Users can save edited images to their phone, open them in other photo apps (Instagram included), or upload them to Facebook, Flickr, Picasa, Tumblr, or Twitter.

3. Streamzoo

Platforms: iOS, Android

Streamzoo is an award-winning app that allows users to organize their photos and videos into streams using hashtags similar to those on Twitter. Users can also find streams from other app users around the world. The app has some great borders, filters, and effects to enhance photos before they're shared with others users. Streamzoo also goes a step further than Instagram -- users can upload videos too.

Privacy and sharing

In his blog post, Zuckerberg wrote he plans on keeping Instagram and Facebook separate.

"We plan on keeping features like the ability to post to other social networks, the ability to not share your Instagrams on Facebook if you want, and the ability to have followers and follow people separately from your friends on Facebook," he said.

However, if you remain unconvinced, here are two apps that offer private sharing, in addition to all the vintage-y filters you love.

4. Pinweel

Platform: iOS

One of this app's best features is private group photo sharing. What this means is that when users create public or private albums, they can choose to share these albums with other users on Pinweel's own network, instead of uploading them to Facebook or Twitter (which is also an option). Another option is that multiple photographers can add photos to albums on Pinweel, making collaboration easy.

The app has its own camera with an on-screen flash button, a button that rotates the frame, and 10 filters. Right now, Pinweel is only available for iOS, but the Android version will be available later this year, according to Mashable.com.

5. Lightbox

Platform: Android

This app has lots of photo filters and gives users the option of making each individual photo visible to friends or to anyone. Users can follow other Lightbox users, or link their accounts to Twitter or Facebook if they choose. The best part about Lightbox is that users can view their friends' Twitter and Facebook photos in the app, even if they don't have Lightbox accounts.