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The Best Open-Source Mood Trackers for Android (2026)
An open-source mood tracker solves a problem that closed apps can only make promises about. Your mood log is intimate data, and the usual privacy pitch is a sentence in a policy: "we store it on your device, we don't sell it." With open source, that stops being a sentence you trust and becomes code you can read. If the source says there's no account and no upload, then there's no account and no upload, whatever the marketing says.
This is a roundup of the genuine open-source options on Android in 2026, the ones actually listed on F-Droid where you can confirm the license and the permissions before you install. I've included the app I built, the SoulSync mood tracker, but placed where the features put it rather than at the top, because it wins on some things and loses on others. Every app here was checked against its real F-Droid or repository listing, not a memory of what used to exist.
What "open source" buys you in a mood tracker
Three concrete things, none of which require you to be a developer.
First, the privacy claim becomes checkable. Anyone can read the code and confirm there's no telemetry, no account system, no network call quietly shipping your entries somewhere. You personally might never do it, but the FOSS community around F-Droid is unusually motivated to call out an app that sneaks in a tracker.
Second, it can't quietly turn against you. A closed app can add an ad SDK or a data pipeline in a routine update and you'd never know. With a public repository under a copyleft license like GPL-3.0, that change has to happen in the open, in the commit history, where someone will notice.
Third, F-Droid itself adds a layer. It only lists apps with published source, shows you the full permission list on every page before you install, and builds many apps from source rather than trusting a developer-uploaded binary. The store is part of the guarantee.
The open-source mood trackers worth using
I'll take these roughly in order of how actively they're maintained and how well they fit "mood tracking" specifically, then place SoulSync among them.
Track & Graph
The most actively developed and the most flexible of the bunch. Track & Graph is a general personal-data tracker: you define what you want to record, including mood, and build graphs and dashboards from it, with custom calculations for people who want to go deep. It's GPL-3.0 and was updated recently. The tradeoff is the flip side of its power. It isn't a mood app out of the box, so you do more setup than with something purpose-built, and the correlation analysis is DIY rather than handed to you. If you like configuring your own system, it's excellent.
Daily You
Daily You is an offline-first diary and mood tracker with photo memories and markdown notes, and its pitch is refreshingly blunt: no accounts, no ads, no locked features. GPL-3.0, actively maintained, and a strong pick if you want journaling and mood in one place rather than pure numbers. If your logging leans more "what happened today plus how I felt" than "a stats dashboard," this is probably your app.
Mood Cairns
Mood Cairns is the purist's choice: a fully offline mood tracker with no network access at all, built-in scales for happiness, anxiety, stress, boredom, and pain, plus custom ones, and recent updates. GPL-3.0. It does one thing, does it privately, and doesn't try to be a journal or a fitness app. If "no network permission, mood only" is the spec, start here.
moreDays
moreDays is a journaling app with mood tracking plus a photo-of-the-day and some weight and sleep logging. GPL-3.0 and maintained. It's the closest to a life-logging all-rounder on this list, so pick it if you want mood as one strand of a broader daily record.
MyMood and Mini Moods (with caveats)
MyMood is a minimalist daily-mood-plus-tagging app, MIT licensed, but its last update was in 2025, so it's slow-moving rather than actively developed. Mini Moods comes up in a lot of old roundups, so worth being precise: it isn't on the main F-Droid repository (that page 404s), only on the third-party IzzyOnDroid repo, and it hasn't been updated since 2021. It's a clean little app, but treat it as effectively unmaintained. I'm including both so you don't waste time chasing a name that other articles list without checking.
SoulSync
SoulSync is the app I built, so judge the placement with that in mind. It's a free GPL-3.0 mood tracker with a 10-point scale, activities and photos per entry, a real with-and-without activity correlation, an Insights tab that reads your patterns back in plain language, five themes, and JSON export, all local with no account. On features, especially the built-in correlation stats and Insights tab, it's ahead of most of the list, because none of the others advertise correlation analysis as a named, built-in feature (Track & Graph gets close, but that's DIY).
Where it loses: SoulSync isn't on F-Droid yet. It's on Google Play and as a signed APK on GitHub, and the source is public, but it isn't in the FOSS store its own audience browses. That's a real distribution gap, and if "must be installable from F-Droid today" is your hard requirement, SoulSync doesn't meet it right now. Track & Graph, Daily You, and Mood Cairns do.
Side by side
| App | License | On F-Droid | Focus | Maintained |
|---|---|---|---|---|
| Track & Graph | GPL-3.0 | Yes | Flexible data tracking incl. mood | Active |
| Daily You | GPL-3.0 | Yes | Diary plus mood, photos | Active |
| Mood Cairns | GPL-3.0 | Yes | Offline mood only, no network | Active |
| moreDays | GPL-3.0 | Yes | Journaling, mood, weight, sleep | Maintained (Mar 2026) |
| SoulSync mood tracker | GPL-3.0 | Not yet (Play plus GitHub) | Mood plus correlation stats and Insights | Active |
| MyMood | MIT | Yes | Minimal daily mood | Slow (2025) |
| Mini Moods | MIT | IzzyOnDroid only | Simple calendar moods | Stale (2021) |
The honest read: there's no single winner, and which one is "best" depends on what you weight. Want the deepest built-in stats? SoulSync. Want it from F-Droid today, mood-only, no network? Mood Cairns. Want configurable everything? Track & Graph. Want journaling with your moods? Daily You or moreDays. All of them are private and auditable, which is the whole point of shopping in this category.
Why open source matters more here than almost anywhere
Mood data is the kind of thing you'd never post publicly, so it's exactly the kind of thing you should be most careful about handing to a server. Open source is the mechanism that turns "trust us" into "check us." It's the same argument that applies to any tool sitting on top of your private behavior. We made the identical case for an open-source app blocker with no internet permission: the strongest privacy guarantee isn't a policy, it's a constraint you can read in the manifest.
FAQ
What's the best open-source mood tracker on Android?
There isn't one answer. For the richest built-in stats, SoulSync. For an F-Droid, mood-only, no-network app, Mood Cairns. For flexibility, Track & Graph. For journaling plus mood, Daily You or moreDays. All are GPL-3.0 and private; pick by whether you want depth, minimalism, or configurability.
Are these really private?
Yes, and you can confirm it. Open source means the code is public, and F-Droid shows the full permission list before install. Apps like Mood Cairns request no network permission at all, so nothing can leave the device even in principle. That's a stronger guarantee than a closed app's privacy policy.
Is SoulSync on F-Droid?
Not yet. It's on Google Play and as a signed APK on GitHub, and the source is public under GPL-3.0, but it isn't in the F-Droid repository at the time of writing. If installing from F-Droid is a hard requirement for you, pick one of the apps above that's already listed there.
Which is best for detailed statistics?
SoulSync, if you want it handed to you: a 10-point scale, activity correlations, and an Insights tab are built in. Track & Graph can go deeper, but you build the analysis yourself with its custom calculations. Depth versus done-for-you is the real choice.
Are open-source mood trackers free?
Every app in this roundup is free with no subscription. Open source and free usually travel together here, since these are community projects rather than businesses with a paid tier. If avoiding subscriptions specifically is your goal, mood trackers without a subscription covers the free options against the paid ones.
If you want the deepest built-in stats with a fully local, no-account design, SoulSync is free on Google Play and open source on GitHub. If your priority is installing from F-Droid today, Track & Graph, Daily You, and Mood Cairns are all solid, all GPL-3.0, and all worth a look.