How do you transfer logins / passwords to clients?

When all the current tasks I already sent to the outsourcers to the Chinese When once again I needed to transfer the username / password to the client, and to the standard offer to send the server ip in skype, and the username / password via SMS, I received a counter offer - “Do not worry, let's all drop off here in skype chat! ”, I felt sad.

On duty, I quite often give all kinds of confidential information to clients, and in 90% of cases, at the initiative of clients, the transfer occurs via email / Skype. Everyone understands why it is unsafe. Googling a bit, I did not find any suitable service for the transfer of confidential data, and decided to write it myself. (Looking ahead, I hasten to inform you that there were already 3 such services, but at the time of the decision to create my service, I did not have this information.)
The essence of the service is simple, save the message for the client in an encrypted form, provide the client with a one-time url to view the message, burn the message after reading , after viewing, delete the message from the database.
It is said - done, node.js + mongodb + 2 days off = SafeMsg.Me
Login only by https, the database is encrypted with AES, after reading the message is deleted.
Now I only give url to clients.

Dear, how do you transfer passwords / logins to your customers?
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PS: Other services providing similar services:
TMWSD
Onetimesecret
Privnote
allw.me