US state legislature bills and lawmakers.
OpenStates API is a free Government API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Documentation for the Open States project.
Details from openstates.org.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Unofficial Philippine Professional Regulation Commission's examination schedule
The OpenStates API is provided by Open States (openstates.org). Documentation for the Open States project.
Yes. The OpenStates API is listed in the Government category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The OpenStates API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the OpenStates API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The OpenStates API is served over HTTPS, so it's safe to use in production.