Pretty cool, reminds me of content from SeekingAlpha.

I'm trying to do something unrelated with public companies, where did you get a list of all companies filing with the SEC? Or was it built based on whoever filed 8-Ks? A google search leads me to this list [0] but it's missing a few companies.

[0] https://www.sec.gov/files/rules/other/4-460list.htm

The EDGAR website has a symbology of CIKs where all companies, people and events are listed.

There is an API, and daily historical snapshots available.