WhatsApp is famous for compressing its images so that beautiful pictures look like they were shot from an old camera phone.
But there is an easy trick WhatsApp into sending a large image without having to download any third-party software.
The screenshots for this article are for iOS since I have an iPhone handy, but I’ll also explain the process for Android as well since the primary mechanism is basically the same: you have to make WhatsApp think you’re transferring a document, rather than a photo.
To start, you’ll need to keep your image as something other than a picture. In Android, you can do this by changing the name your image as a .pdf or .doc file in your file manager in your phone, which will save it as the file type. Then, when you send it to the sender, tell them to change the name the image in their own file manager as .jpg and it’ll display up as the original, uncompressed image for them so problem solved.
In iOS, you can store your images to your Files app which you will find on your phone. Select an appropriate folder, either for an app already on your phone or you can also save on your iCloud Drive.

Go and save your image, pull up your WhatsApp contact of choice and tap the plus sign button to add an attachment to your message. After that select “Document” rather than “Photo.” This will open up your Files, and from here you can search and select your image. It’ll send as an uncompressed document instead of a compressed image.

In Android, the method can be even sharper than the method we mentioned above, simply by sending the image as a “Document” rather than a “Gallery” file. You should find your pictures under a special folder. If you don’t see it quickly, tap “Browse other docs.”
There are plenty of other third-party apps (using Dropbox, Google Photos, Evernote, etc), but if you want to send out a quality picture without having losing the quality in WhatsApp and your built-in software, this is the best way to do it.