The Web Extension API is required if you want to download resources blocked via the "Same-origin policy", see https://developer.mozilla.org/en-US/docs/Web/Secur

The Web Extension API is required if you want to download resources blocked via the "Same-origin policy", see https://developer.mozilla.org/en-US/docs/Web/Security/Same-origin_policy https://developer.mozilla.org/en-US/docs/Web/Security/Same-o.... This is the main problem and it is quite common. This could be circumvented by using a proxy, but this would introduce security issues.