ToneBird

ToneBird is a desktop AI reply assistant. Its selling point is "remembering people": remembering your relationship with each contact, what you have talked about before, and what tone you usually use, and then directly help you draft the next reply in applications such as Gmail, Slack, iMessage, WeChat, and X.

You can also quote the documents you linked in, so you don’t have to look through the materials yourself when answering work questions. Drafts will not be sent out automatically. It is up to you to pick one, revise it and then send it out.

There are Mac and Windows clients. Free version has 15 drafts per day and up to 30 contacts; Standard is $9.9 per month and Pro is $39.9 per month. People who reply to a lot of messages every day and don’t want every message to look like a template will find it more useful.