Phone number validation and carrier lookup API with global coverage.
Numlookup API is a free Phone API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Number lookup API for 230+ countries: validate phone numbers, get the carrier, line type and VoIP flag, and format them to E.164. 100 free requests a month.
Details from numlookupapi.com.

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The Numlookup API is provided by numlookupapi.com (numlookupapi.com). Number lookup API for 230+ countries: validate phone numbers, get the carrier, line type and VoIP flag, and format them to E.164. 100 free requests a month.
Yes. The Numlookup API is listed in the Phone 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 Numlookup API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Numlookup API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Numlookup API is served over HTTPS, so it's safe to use in production.