Web Based Tools

Mass Action Scheduler 

Create scheduled actions, declaratively and without code.

https://douglascayers-org.github.io/sfdx-mass-action-scheduler/

 

CloudToolKit

Is actually 8 tools - Best practices analyzer, Org Compare tool, Data Compare tool, Schema Lister, Field Creator and validation/trigger switcher

https://cloudtoolkit.co/

 

Workbench

https://workbench.developerforce.com/login.php?startUrl=%2Fquery.php

 

Declarative Lookup Rollup Summaries (DLRS)

https://github.com/afawcett/declarative-lookup-rollup-summaries 

 

Profile Power Tools

https://profilepowertools.com

 

Google for salesforce

https://sfdcsearch.com/

 

Json 2 apex 

http://json2apex.herokuapp.com/

 

Cert Score Calculator

https://scuvanov.github.io/SalesforceCertScoreCalculator/