Each Country separately and Worldwide Graphs for Coronavirus. Daily updates.
Graphs for Coronavirus API is a free News API that requires no API key, is served over HTTPS and supports CORS, so it can be called from the browser.

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Yes. The Graphs for Coronavirus API is listed in the News 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.
No. The Graphs for Coronavirus API requires no authentication, so you can start making requests without signing up.
Yes. The Graphs for Coronavirus API supports CORS, so front-end JavaScript can call it directly.
Yes. The Graphs for Coronavirus API is served over HTTPS, so it's safe to use in production.