Butler inspector
Quick and easy way to see what the Data Source and Doc Config would retrieve for a given record or a given locale. I used to maintain a Word Doc containing all of my merge tags so I could do this kind of validation/troubleshooting. Now I don't have to worry about that. Must-have tool if you're a Salesforce Admin for an org that runs PDF Butler, Sign Butler, etc. Thanks PDF Butler Team!
A nice tool to have if you use PDF Butler
zcchen.dev
Maven Mule
https://www.salesforcementor.com/
https://synebo.io
https://nisar-99.github.io/
Sameer N Miraj
Salesforce
Steve Babula
http://www.xgeek.net/
Thomas Prouvot
Abrar Khan
Ravi Narayanan