I think the OP (hat off!) needed a way to transfer data to the front-end of another application. Since there's no back end involved, the only available channel is the request URL
> Since there's no back end involved, the only available channel is the request URL
Not quite. I have a system that uses a custom userscript to create an extra button on certain webpages that, when clicked, scrapes some data from the current page and copies a lightly encoded version to the user's clipboard. They then switch to another webpage and paste it in a box.
I've also gotten data from place to place using scraping from temporary iframes (same site).
That guess was actually quite close. The target system does support the GET way out of the box as a way to pre-fill data into a form; but only over GET.
