Octopus Energy Watchdog

Octopus Energy Watchdog is a third party app designed for Octopus Energy customers in the UK, which will help you quickly keep an eye on your energy tariffs. Please note that due to API restrictions, the app will only work for Agile tariff customers (so it won't be useful if you're on a fixed tariff or on the Go tariff). Once the API will allow, the app will be updated to add support for other tariffs.

It features an easy-to-read chart which you can scroll through and see immediately when it's the best time to do your laundry, or charge your electric vehicle.

On top of that, you can see a rolling 30-day usage for your household without having to wait for your bill, helping you make informed choices on a day-to-day basis and ultimately save money. You can also zoom into an individual day and see your usage against historical tariffs at that point.
It also supports gas consumption charts (although without tariffs as this data is not accessible yet).

Please note that the developer is not affiliated with Octopus Energy, and this application is provided as-is. Your login details do not get sent anywhere or even stored on your phone, once the necessary API keys and parameters will be stored within the app. If privacy is a concern, it's also possible to enter them manually.