Plot Digitizer - All-in-One Tool to Extract Data from Graphs, Plots & Images
WebPlotDigitizer - WebPlotDigitizer - Web based tool to extract numerical data from plots, images and maps.
DigitizeIt - Sometimes it is necessary to extract data values from graphs, e.g.
Engauge Digitizer - This open source, digitizing software converts an image file showing a graph or map, into numbers.
g3data - g3data is used for extracting data from graphs.
2d Data Plotter - 2d Data Plotter is a simple graph plotting Android app that you can use to plot 2-dimensional X-Y data with ease.