I found this... Something like what you have in mind? (not Foss) https://plotdigitizer.com/ https://plotdigitizer.com/ Ed: or maybe this (gpl) - didn't realiz

I found this... Something like what you have in mind? (not Foss) https://plotdigitizer.com/ https://plotdigitizer.com/ Ed: or maybe this (gpl) - didn't realize this existed... https://markummitchell.github.io/engauge-digitizer/ https://markummitchell.github.io/engauge-digitizer/ Ed2: another along similar lines (pun not intended). Looks like most assume you have a bitmap of a graph, rather than let you just draw datapoints. https://automeris.io/WebPlotDigitizer/ https://automeris.io/WebPlotDigitizer/