URL to screenshot.
Screenshotlayer API is a free Photography API that requires no API key, is served over HTTPS and has unconfirmed CORS support.
Free URL to Screenshot API - capture crisp and clean snapshots of any website, with any device, any setting and lightning fast. Free for personal use.
Details from screenshotlayer.com.

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Image manipulation and processing
The Screenshotlayer API is provided by Screenshotlayer API (screenshotlayer.com). Free URL to Screenshot API - capture crisp and clean snapshots of any website, with any device, any setting and lightning fast. Free for personal use.
Yes. The Screenshotlayer API is listed in the Photography 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 Screenshotlayer API requires no authentication, so you can start making requests without signing up.
CORS support for the Screenshotlayer API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Screenshotlayer API is served over HTTPS, so it's safe to use in production.