Downloadable version here. This one is read-only and won’t save your changes.
This is a tool I created so I could look at my Codex and find out what Datacrons I had gotten and which I hadn’t. You’ll want to filter by faction to start (blank means both factions.) From there, you could check off datacrons you’ve picked up (scroll right to columns H and I) and filter those out. You can also do things like check datacrons for the planet you are on (filter on Planet) or look at the list of all datacrons related to your main stat (filter on stat.)