Nitpick: the video refers to the site content as “tabs,” but I’d call it a chord chart instead. Tablature is specifically notation for individual notes on fretted instruments — e.g., play the second fret on the B string. I didn’t see any single-note stuff in your product, unless I missed it...?
All of that is to say: As a musician, I groaned when I heard you describe that as “tabs.” I expect other musicians would have a similar reaction (“um, this company doesn’t know what a tab is”), or at least they’d be confused due to expecting something else.
My own company Soundslice (https://www.soundslice.com/) does proper tabs and standard music notation, though I wouldn’t call it a competitor. We’re more about learning existing tunes than songwriting. Welcome to the wonderful world of web music software!