Capture screenshots of web pages at different viewport sizes using HTML canvas and iframe rendering.
Enter a URL, choose one or more viewport sizes, and the tool renders the page inside an iframe sized to each viewport, paints what renders onto an HTML canvas, and exports a PNG. Because the capture is drawn by the browser itself, every screenshot obeys the browser's rules for iframes and canvas. Users most often discover the hard way that most real-world websites cannot be captured: sites that refuse to render in an iframe, or that block cross-origin canvas reads, come back blank or with a security error. The tool is for pages that allow embedding - in practice, pages on the tool's own origin or sites you control.
You supply a URL and choose one or more viewport sizes. The tool loads the page into an iframe sized to the viewport you picked, waits for it to render, then paints the iframe's pixels onto an HTML canvas element and exports the canvas as a PNG. Choosing several viewports produces one image per size, so a single run yields mobile, tablet, and desktop captures of the same page.
Every capture obeys the browser's rules for iframes and canvas. A page that sends X-Frame-Options: DENY or a frame-ancestors Content Security Policy will not render inside the iframe, so the capture is blank. A page that renders but sits on another origin without permissive CORS headers taints the canvas, and exporting the pixels throws a security error. Both outcomes are the browser enforcing policy, not the tool failing.
Because that page sits on another origin and does not permit embedding or canvas access. Cross-origin pages can only be drawn to a canvas if they send an Access-Control-Allow-Origin header, and they only render in an iframe if framing is allowed; most sites do neither. This is a browser security rule, not a tool defect. Capture pages on the tool's origin, or sites you control with the needed headers.
No. The page loads inside an iframe in the tool rather than in your own tab, so the capture context does not carry your logged-in session: account-gated or personalized content will not appear, and ads, embeds, and fonts may load differently or not at all. Treat the capture as a clean-environment render of the page's HTML and CSS, not a pixel-perfect copy of your browser window.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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