Send someone a password or API key

You need to get a credential to a colleague, and the obvious channels (Slack, email, a ticket) keep a copy forever.

When you are done: A link that decrypts only in the recipient's browser, which you can also make readable exactly once.

Steps

Open the paste form and turn on end-to-end encryption before typing anything.
Turning it on first means the plaintext never sits in a draft that gets submitted by accident.
Paste the credential.
Set the expiry to the shortest window that works, or choose burn-after-read.
Burn-after-read destroys the paste on first view. Use it when exactly one person needs the secret once.
Create the paste and copy the whole link, including everything after the # character.
The part after # is the decryption key. A link without it is undecryptable, by us and by everyone else.
Send the link, and save the owner key somewhere you can find it.
The owner key is what lets you delete the paste early. It is shown once.

If you drop the part of the link after #, the content is gone permanently. There is no reset and no copy on our side to fall back on.
Burn-after-read triggers on the first view by anyone, including a link preview bot in the chat app you send it through. If the recipient reports an empty page, assume something else opened it first and rotate the credential.
Encryption stops us and anyone with our database from reading it. It does not stop the recipient from screenshotting it, and it does not protect you from a browser extension with permission to read the pages you visit.
Rotate the credential afterwards if it is important. A link that has been sent is a link that could have been forwarded.