Vehicle info, pricing, configuration, plus much more.
Kelley Blue Book API is a free Vehicle API that requires apiKey authentication, is served over HTTPS and does not support CORS, so it should be called from a server.
Details from developer.kbb.com.

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.
Telematics data, remotely access vehicle functions, car configurator, locate service dealers
Vehicles information from Fundação Instituto de Pesquisas Econômicas - Fipe
NHTSA safety recalls by model year, make and model with component, consequence and remedy
The Kelley Blue Book API is provided by KBB Developer Portal (developer.kbb.com).
Yes. The Kelley Blue Book API is listed in the Vehicle 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 Kelley Blue Book API uses apiKey authentication, so you need to register for credentials before making requests.
Not directly. The Kelley Blue Book API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The Kelley Blue Book API is served over HTTPS, so it's safe to use in production.