How to export private key from Casper Signer?

Step 1: From the main interface, click on the 3 horizontal lines on the top right and choose “Download active key”

Step 2: There you go, the file you’ve just downloaded is “the chest” of your private key. Now let’s open it. Make sure to right click on the file, then choose “Open with…”, and choose a text editor tool.

Step 3: Copy your private key and keep it safe, also the file.