Oh they had an API 8 years ago too. It’s just that they only let you use that API from JavaScript running on your users’ browsers.
The undocumented tiny ratelimits and threat of bans for server-side API users (while no such ratelimits applied to the HTML pages) forced pretty much every app to scrape their HTML server side.
From my README which quotes their old docs: “Note: The United States Postal Service expressly prohibits the use of Web Tools "scripting" without prior approval. Web Tools scripting can be defined as a technique to generate large volumes of Web Tools XML request transactions that are database- or batch-driven under program control, instead of being driven by individual user requests from a web site or a client software package. The USPS reserves the right to suspend server access without notification by any offending party that does not have prior approval for Web Tools scripting. Registered Web Tools customers that believe they have a legitimate requirement for Web Tools scripting should contact the ICCC to request approval.”
