"Modern image viewer" = decent. It is a sales pitch so at least you included something regular users would want to read about.
Electron and NodeJS = bad. Only developers care about that. IMO keep that in the "About" page or just on Github.
"View on Github" is a bit redundant, you already have a tab for that.
Make the Download button bigger and more prominent. I believe the standard color for download buttons is green.
Core features: again, the first feature ("Electron") should go. The other 5 are valid for users. BTW, IMO pull a summary of those features as part of the slogan aka sales pitch used above.
Settings: make that a separate page. It's super scary for regular users.
Also: list the file formats supported somewhere on the home page, preferably in a section which is easily visible. If the file format list isn't yet as big as you want, you could list some of the formats you plan to support soon (but mark the "work in progress" ones clearly.
Cool project!