How to get your Messenger data
Go to your Facebook settings (web version) -> Your Facebook information -> Download your information
Select "All of my data" for the date range, "JSON" for the format, and "Low" for media quality (this will make the download as small as possible)
Press "Deselect all"
Find and tick the box for downloading "Messages"
Click "Create File"
Wait (this could take hours) and then download your file (Facebook should email you with a link when it's ready)
Open the zip and go to messages -> inbox -> the name of the conversation you want
You should now see a few directories (ignore them) and either 1 or a few "message_x.json" files, extract these .json files and use them in the section below
Using this website
Click on "Browse" and select
of the "message_x.json" files from conversation directory (where "x" should be a incrementing number)
Click "Get Stats"
Main website CSS: