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This website is not encrypted man...there is no way in hell I am putting any of my keys in here...try letsencrypt

This a post for testing the publisher, but I will answer your question. If you use your keys they will always be safe on your browser, this app is serverless, so there is no way I can know your keys.

Also is open source, you can review the code and see what I do with the keys of the users, that is nothing, they enter their keys only for posting.