php

demo.grn.dk is where the experiments live: twenty-five of them, from an XHTML-era sunrise calculator for Silkeborg to procedural WebGL, a Blender orrery, a crystal hall, an AI receptionist, a UK accounting autopilot and a Danish ERP day. Many of the cases on this page open on a shelf entry. The shelf itself is one PHP file that lists the demos, groups them into Featured and Tools, filters as you type and derives the sitemap from the same list — so a demo that lands in the web root is on the shelf and in the sitemap before anyone writes it up.

Twelve production websites on one server, each with its own Composer dependency tree, and the oldest question in hosting: are they up to date, and is it safe to make them so? The dependency-currency gate answers it weekly and automatically — it inventories every vhost, checks each dependency tree against the PHP version that site's web server actually runs, queues the semver-safe updates for approval, and reports the breaking ones instead of applying them.

A Danish coworking space wanted members to book a table by the hour and pay for it — because at 20 kr. per hour per table, a booking that has not been paid for is not a booking. tableflow.grn.dk is that system, built from the client's brief and running live: an hour grid that shows what is actually free, a fifteen-minute payment hold that releases itself, and an admin screen for the people who run the place. Plain PHP and MariaDB — no framework, no dependencies, 853 lines in seven files.