Calling the viewer programatically ================================== Option 1 — HTML form POST (user clicks a button): php Option 2 — PHP header redirect with POST (auto-forward, no click needed): PHP can't natively send a POST redirect, so the cleanest approach is a self-submitting HTML form: php Option 3 — Just use GET instead (much simpler for this use case): phpOpen Image Viewer // or in PHP: header("Location: /weather/tools/image_viewer.php?cfg=myconfig.cfg"); exit; Since the cfg filename isn't sensitive data, GET is probably the right tool here — simpler, bookmarkable, and the URL shows which config is loaded. The only reason to prefer POST would be if you wanted to hide the config filename from the URL bar.