How do you save Snapchats without them knowing?

It's important to note that saving someone's Snapchat without their knowledge or consent is a violation of the app's terms of service and can be considered a breach of trust. Additionally, taking screenshots or using third-party apps to save Snapchats without the sender's knowledge can result in the suspension or termination of your Snapchat account.

That being said, if you want to save a Snapchat for your own personal use, there are a few official ways to do so:

1. Save your own Snaps: You can save your own Snaps by tapping the "Save" button before sending them. This will save the Snap to your camera roll.
2. Use Snapchat Memories: Snapchat Memories is a feature that allows you to save Snaps and Stories to a private collection. To save a Snap to Memories, swipe up on the camera screen and tap the "Save" button. You can then access your Memories by swiping up on the camera screen again.
3. Take a screenshot: You can take a screenshot of a Snap by pressing the "Print Screen" button on your keyboard (on a PC) or by pressing the power button and volume down button simultaneously (on an iPhone). However, Snapchat will notify the sender that you took a screenshot.

It's important to always respect the privacy and consent of others when using Snapchat or any other social media platform.