Check links to see if they're known phishing attempts.
NoPhishy API is a free Anti-Malware API that requires apiKey authentication, is served over HTTPS and supports CORS, so it can be called from the browser.

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.
IP/domain/URL reputation
Malware Archive / file sourcing
Scan URLs in a sandboxed browser and search past scans by domain, IP, ASN, JARM or favicon hash
Yes. The NoPhishy API is listed in the Anti-Malware 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 NoPhishy API uses apiKey authentication, so you need to register for credentials before making requests.
Yes. The NoPhishy API supports CORS, so front-end JavaScript can call it directly.
Yes. The NoPhishy API is served over HTTPS, so it's safe to use in production.