The ephemeral messaging app is taking a permanent stand against third-party apps.

Snapchat said it will notify users if it detects that they are using unauthorized applications created by outside developers. These apps may, for example, provide fun photo editing tools or let users save photos and videos that would otherwise disappear. Snapchatters will be asked to change their passwords and to stop using the third-party apps.

The risk in using third-party apps is that there is no guarantee that other companies would protect user account information. Their servers could also be more easily compromised.

That was the case when nearly 100,000 Snapchat photos and videos were leaked online in what was dubbed the “Snappening.” Accounts that were hacked had used the third-party app Snapsaved, which let users download the disappearing photo messages.

Some Snapchat files contained explicit images of users under the age of 18.The stolen images were posted on online message board 4chan, the same community that had users hack into iCloud accounts of several celebrities including Oscar winner Jennifer Lawrence.

Snapchat has insisted the Oct. 10 incident did not stem from a breach in its own servers.

“We’ve enjoyed some of the ways that developers have tried to make Snapchat better,” the company said on its blog. “Unfortunately, some developers build services that trick Snapchatters and compromise their accounts.”

Staff reporter Melissah Yang can be reached at [email protected]. Follow her on Twitter @MelissahYang for the latest in L.A. tech news.