Tainted canvases may not be exported

less than 1 minute read

How to export a tainted HTML5 canvas to Base64.

Pretty specific but I recently was doing some work with HTML5 canvases. I was reconstructing a type of photo frame and then overlaying an image atop it.

After the canvas was ready, I then wanted to export it to Base64 so that it could be sent over to the server for some additional processing.

Unfortunately I was hitting an error that would not allow me to do that :(

Uncaught DOMException: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported.

After some debugging, it seems that if the image src is from a different ORIGIN, then the canvas is deemed as being tainted. We can get around this by setting the crossOrigin attribute on the HTMLImageElement to be ‘anonymous’ before we draw onto our canvas.
Protip: You need to set this before setting the src.

let image = new Image()
image.crossOrigin = "anonymous";
image.src = 'HTTPS://REMOTE.HOST/IMG';

ctx.drawImage(image, canvas.width/2 - 40, 25, 80, 120);


You should now be able export the canvas to Base64.