Octopus Watch can show you upcoming Agile/tracker rates, and work on its next major is wrapping up. It's bigger (13 vs 5 models), better, and predicts further. Don't expect to see 4+ day predictions in the app but that is exactly what was tried in a test version. ETA: coming in a few weeks.

Update 5.2.1 (Android) and 5.3.0 (iOS) for Octopus Watch rolling out with improvements for subscribers (e.g. dates on carbon screen, chart lock in day details). On iOS a trial is run to set a custom unit rate for the home mini bar. Set it to e.g. the SVT to see your usage above and below this rate.