TagHistory

TagHistory is a tool letting you plot graphs showing tag usage stats over time.

You can compare multiple tags, and so use it to observe a shift in usage over time from one tag to another

A TagHistory graph showing the growth in leisure=swimming_pool mapping and the decline in use of the older tag amenity=swimming_pool

Math1985' diary entry gives more example tag comparisons (and their histories)

API

Developed by Martin Raifer.

Source code and bug tracking on github: https://github.com/tyrasd/taghistory

For the example above (Swimming_pool_amenity_vs_leisure_Taghistory.png) the corresponding permalink looks like:
https://taghistory.raifer.tech/#***/leisure/swimming_pool&***/amenity/swimming_pool