A fake chat is a picture you export
ChatCanvas guide
Same tool, plain name
People search for a fake chat generator. The thing they want is a realistic conversation they can edit and download. That is this. WhatsApp, iMessage, Slack, and Gmail each have a page that opens the editor on that skin.
It does not send the message. A fake WhatsApp chat is a PNG or an MP4. A Gmail mockup is not connected to an inbox.
Where to start
For a text-message screenshot, start with WhatsApp or iMessage. For a slide, start with Slack or Gmail. Export PNG for a still and MP4 when the messages should appear in order.
Keep the people fictional. A mockup for a demo, a meme, or a storyboard is fine. A fake chat presented as something a real person sent is not.