Meta Search - Search your Desktop, Google Drive, Dropbox, Gmail, Evernote.
Plot Digitizer - All-in-One Tool to Extract Data from Graphs, Plots & Images
Findo - Your smart search 🔍 assistant across personal cloud ☁️
Engauge Digitizer - This open source, digitizing software converts an image file showing a graph or map, into numbers.
FYI - Find your documents, like magic 🔮
DataThief III - DataThief III is a program to extract (reverse engineer) data points from a graph.