I built a web app called Bucket for tracking todos, inspired by the technique described in this video[1] whereby you put tasks into buckets based on the time horizon for completion.
Your tasks are stored entirely in your browser, so there's no back-end, no risk of losing access, works offline, you can export any time, and you can share your tasks between devices using the Sync URL. You can use it here (for now, looks best on mobile): https://lusmo.re/bucket/
I built it because it was easy, it does exactly what I want, and I don't need to rely on some 3rd party to profitably monetise todo apps so that I can use it indefinitely.