Opportunity Stage Tracker

Hello,

has anyone a solutions to track the time an opportunity or account is within a specific sales stage?

I want a Number in Days to work with.

This seems to be a solution but not available anymore.

https://www.sugaroutfitters.com/addons/stage-tracker

For example if an Account is in a specific Stage without activity a will assign him to an other agent.
Or,… for general reporting how long the accounts stay at what Stage per agent…