I am definitely not OP. But I would guess there is some background agent or cron job running that populates his database from the dataset api. From that there is the web site that reads from the db to render the two visualizations - graph and table.

His methodology page describes where this data comes from: https://www.govtrades.com/methodology

Incidentally someone sent me this link today; a list of charting libraries: https://thenextweb.com/dd/2015/06/12/20-best-javascript-char...

edit: on closer inspection it appears the charts are provided by squarespace. So maybe squarespace also provides the connector for back end data as well??

please correct me if I'm wrong or terse