We have an electricity tariff that changes price every half hour. This is obviously a stupid distraction, a useful money-saving measure (I’ve saved about a third of my electricity costs over the last year) and a little taste of the future. Alongside that, it is a deep temptation to organise my life around this once it is there.

This is not my first go at making Octopus prices useful. Last year I wrote Octopus Agile Prices For Linux, which became Agile Rates, a GNOME app for smart tariff rates, cheap-time finding and usage history. Agile Prices is the smaller Android and Wear OS version. You choose your UK electricity region, it finds the current Octopus Agile import tariff and caches the upcoming half-hour rates. There is no account API key, usage history, export tariff support, Go support, Intelligent Go support, spend analysis, widget, notification system or attempt to become an energy management platform in miniature.

That is mostly intentional. If I am standing by the washing machine I do not want an energy dashboard. I want to know the current price, how long to set the timer for, and whether the cheap bit is soon enough for the clothes to be dry before everyone has to leave the house.

The app keeps two controls in the foreground: run time and search horizon. By default that is a one-hour load inside the next eight hours. There are lots of small details about how this search works, but the point is that it finds the cheapest time in a way that fits the appliances you have and the tariffs that exist. On a watch we are blunt. Current price, best run window, run-time and search controls, the next few slots, refresh, region details. It has a Wear Tile for the current price and cheapest window, and a complication for the watch face. That is the version I wanted first: glance, decide, stop prodding the tiny screen.

The phone version gives the same data more room. It has the current price, cheapest window, planning sliders, setup and cache details, plus an interactive 24-hour graph. The graph marks the chosen cheap run, lets you tap or drag through half-hour slots, calls out negative prices and shows the visible price swing when it is large enough to be worth noticing. On wider Android or ChromeOS windows it becomes a two-pane layout. Whilst I mourn the passing of ordinary Chromebooks, I am not insensible to the future. The nice sparkline graphs I worked on here have inspired a visual refresh on the GNOME side as well. Iteration often benefits from a different perspective.

I used Codex heavily while building it. This is still an app almost entirely for me, which is why the shape is so specific. Wider use cases are encouraged to enjoy Octopus Compare, which is a much better app with many more features and which I pay a subscription fee for. But it does not let me constrain the ideal search time to the next few hours, and so keeps telling me to run the washing machine tomorrow afternoon when I need the contents tomorrow morning.

If you want it now, build it, or build your own. Agile Prices is independent and is not affiliated with, endorsed by or sponsored by Octopus Energy.