Mathew Brown

I Published an Android App to F-Droid

04 June 2026 • 2 min read
android privacy open-source running fdroid
Table of Contents

I've been running the Couch to 5K program on and off for years. Every Android app I tried either needed a Google account, wanted to sell me a subscription, or was riddled with tracking I didn't want. So I built my own and published it to F-Droid.

It's called C2K.

What it does

C2K guides you through the classic Couch to 5K program (9 weeks) and, once you've finished that, the Couch to 10K extension (14 weeks). The structure is simple: interval training three days a week, alternating walking and running segments that gradually shift toward longer runs as your fitness improves.

During a workout the app gives you audible voice prompts — "Start running", "Walk for 90 seconds", 30-second countdown warnings — so you can put your phone in your pocket and focus on moving. The timer keeps running with the screen off and shows controls on the lock screen. GPS tracking is available if you want distance and pace, but the app works just as well without it.

It remembers your progress across sessions. If you finish week 3, day 2, that's marked complete when you come back.

Why not Google Play

Two reasons.

First, I run GrapheneOS and I don't have Google Play Services installed. Any app that requires them is already out of the picture for me. C2K has no INTERNET permission at all — it is completely offline. No account, no analytics, no telemetry, nothing phoning home.

Second, F-Droid builds apps from source. The binary you install is reproducibly built from the public code, not a binary I uploaded. That's a meaningful trust model difference. F-Droid can verify the app is what the source says it is.

Getting it

Search for C2K in F-Droid, or go straight to the listing: f-droid.org/en/packages/com.hackerapps.c2k.

The source is on GitHub at AnalogGhost/c2k under GPLv3. If you want to build it yourself, the README has everything you need.

I built this for myself and figured someone else might find it useful. If you're trying to start running and you'd rather not hand your GPS data to an ad network, give it a try.

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