The data is pulled directly from AWS docs, the same JSON endpoint their pricing page pulls it from, so the data is always up to date. The pricing is for "on-demand" and "reserved 1yr convertible" instances, US-East only for now.
The reason I built this is because my favorite "goto" tool - https://ec2instances.info/ - has been acquired, lacks updates, has some unfixed bugs and misses some pricing. So I put together this little app to pull the data from AWS docs directly and display it in a sortable table.