KTool[0] is fairly new so I can't claim it "outperform" Amazon's solution. However if you read the recent reviews from their Chrome Extension page[1], the majority of complaints was that the article never arrived.

I just tried sending this article[2] and 10 minutes later it still hasn't delivered yet. This article contains a lot of images, so I understand it's not going to be quick, but with KTool, it does deliver within 2 minutes.

But that is not the only reason why I build KTool. I don't want the articles to include links when reading on my Kindle because it's bad UX (easy to mis-tap), distracting and reduce comprehension (see here[3] and here[4]). Instead, I push all these links to the bottom of the article, which make it still accessible yet improve the reading experience.

[0]: https://ktool.io

[1]: https://chrome.google.com/webstore/detail/send-to-kindle-for...

[2]: https://waitbutwhy.com/2017/04/neuralink.html

[3]: https://www.wired.com/2010/05/ff-nicholas-carr/

[4]: https://www.roughtype.com/?p=1378