Best Open-Source To-Do Apps for Privacy in 2026

Open source lets you inspect and modify a task app. It does not tell you whether its server can read your tasks. This shortlist starts with public code and an open-source app license, then separates local use, server ownership, and encryption. Choose the configuration, not just the logo.

Direct answer: which open-source to-do app should you choose?

Choose Tasks.org for Android tasks with flexible sync, Super Productivity for local-first planning and time tracking, Vikunja for self-hosted collaboration, and Taskwarrior for command-line control. Joplin qualifies when checklists inside notes are enough. For provider-blind task content, select a documented encrypted configuration: EteSync with Tasks.org, encrypted Super Productivity sync, TaskChampion server sync, or Joplin E2EE. Open source alone provides no such guarantee.

Methodology and facts checked: October 28, 2026

This is a review of official documentation, public licenses, release records, and relevant Zero-Friction implementation, not a hands-on comparison or security audit. The five shortlisted app projects have public source, an open-source app license, and a published non-prerelease release checked today. Release activity indicates maintenance, not security certification.

The criteria are license eligibility, offline/local behavior, self-hosting options, sync operator, task-content encryption, platforms, task features, and operational effort. Effort labels are editorial judgments about configuration and server responsibilities, not measured installation times. Platforms refer to the documented app or interface; a CalDAV-compatible desktop client is not a native Tasks.org desktop release.

We did not assign a privacy score or invent performance benchmarks. We also did not equate “free source code” with free managed hosting. Hosted services, app distribution, subscriptions, and infrastructure can cost money. No numerical hosted-price comparison is made here.

For Super Productivity, the sync claims below use its v19.3.1 sync-provider reference, rather than treating every website slogan as a technical guarantee. For Joplin, app eligibility does not imply that every server component has the same license.

Open source, self-hosting, and E2EE answer different questions

Open source gives you rights under the software license and access to inspect or modify the covered code. A public repository with a restrictive license is not automatically an open-source product. A project can also apply different licenses to different directories, so check the component you intend to deploy.

Self-hosting changes who operates the server. You can control its location, access policy, updates, and backups. It does not prevent your server administrator, database access, or compromised server software from reading plaintext that the application processes.

End-to-end encryption (E2EE) protects content before upload so that the sync service lacks the content-decryption secret. It is different from HTTPS/TLS, which protects transport to a server that may read the request, and from disk/database encryption at rest, where the operator may hold the key.

None of these automatically encrypts the app's local database, exported files, notifications, or all metadata. Account records, connection details, identifiers, timestamps, and file sizes can remain visible even when task content is encrypted. Exact fields depend on the product and sync mode; unknown coverage is not evidence of encryption.

If licensing is not your deciding constraint, our encrypted to-do app comparison covers a broader field. This article keeps open-source app eligibility as its organizing filter.

Tasks.org: Android tasks, with privacy determined by the backend

Tasks.org's documentation identifies it as an Android task manager. The app is GPLv3, supports offline use, and offers recurrence, notifications, filters, and subtasks. It is a practical shortlist candidate if you want a dedicated Android task interface without making a cloud account the starting point.

The important decision is sync. Its official comparison lists Tasks.org Cloud, Google Tasks, Microsoft To Do, CalDAV, DAVx⁵, EteSync, and DecSync CC. These are not equivalent privacy models. Tasks.org Cloud uses CalDAV; that is interoperability, not a claim that the operator cannot read task content.

The documented E2EE option is EteSync. You can use its hosted service or run a compatible instance yourself. Tasks.org can connect through the EteSync Android client or directly to an EteSync host. Local lists and EteSync lists are separate: existing local lists do not become encrypted remote lists merely because you added an account.

Choose plain CalDAV when broad compatibility and control over your server matter more than hiding content from that server. Choose EteSync when its encrypted sync model matches your requirement. In either case, check the feature matrix before migrating: not every reminder, attachment, or other field synchronizes with every backend. Do not promise a complete transfer from the presence of a sync button.

Best fit: Android users who want mature task controls and can deliberately choose a backend. Poor fit: someone expecting a single official Tasks.org native app on every desktop and phone platform.

Super Productivity: local-first planning, with configuration-specific encryption

Super Productivity is MIT-licensed and combines tasks, time tracking, timeboxing, and focus tools. Its download page documents desktop, mobile, and web options. Local work does not require a sync account; connecting a provider introduces a separate trust boundary.

The release-specific sync reference distinguishes file-based Nextcloud/WebDAV and Dropbox sync from SuperSync. File-provider encryption is optional. If you skip encryption setup, the fact that the storage provider uses HTTPS or encrypted disks does not make the application data E2EE against that provider.

SuperSync is documented as beta, with required end-to-end encryption for its payloads and a password that stays on the device. Technical metadata such as identifiers and timestamps remains outside that encryption. The same reference warns that self-hosting support is limited and recommends more established providers for production use until SuperSync is stable.

That is a more useful assessment than “open source, therefore private.” Local-only use, encrypted file sync, and SuperSync each have different setup and recovery responsibilities. Keep the encryption password separately: the reference says encrypted server data cannot be recovered if that password is lost.

Also resist a tempting shortcut: the current documentation describes local-file sync as a single-device backup target, not a folder to mirror between devices with generic file-sync software. It warns that concurrent writers can overwrite one another. Use a documented multi-device provider instead.

Best fit: people who want daily planning and time records in one local-first app. Poor fit: users seeking only a minimal inbox, or those who would enable beta sync without accepting its support and recovery trade-offs.

Vikunja: open-source server ownership, not provider-blind tasks

Vikunja offers an AGPLv3 core with shared projects, task assignments, and list, Kanban, Gantt, and table views. You can run your own instance or choose managed Vikunja Cloud. Its browser interface makes it relevant when a household or team needs to work together rather than maintain separate personal inboxes.

The privacy benefit of self-hosting is control over the operator and deployment. It is not evidence of task-content E2EE. The reviewed security-hardening guide describes server/database access, TLS termination, file storage, backups, and access control. Treat the instance operator as trusted with task data; no provider-blind content model was established in the reviewed sources.

Deployment details matter. The hardening guide says Vikunja serves plain HTTP by default and recommends TLS at a reverse proxy. Encryption in transit therefore needs to be part of your deployment, not assumed from the application's license. Database permissions, restricted ports, updates, and encrypted backups remain operational responsibilities.

Scope the licensing claim too: the core is open source, while the current documentation marks some capabilities as Pro. Do not assume every enterprise feature is included in the self-hosted core. If you choose managed hosting, control shifts back toward a service operator even though the core source remains inspectable.

Best fit: users or teams with a maintained server and a need for shared work. Poor fit: someone requiring task content to be cryptographically hidden from the server administrator, or expecting no server maintenance from self-hosting.

Taskwarrior: local command-line control, with encrypted TaskChampion sync

Taskwarrior is an MIT-licensed command-line task manager. Its strengths are structured tasks, recurrence, tags, dependencies, filtering, and automation rather than a polished graphical planner. The installation reference documents Unix-like platforms and directs Windows users toward WSL.

You can keep the task database local. For cross-device use, the sync documentation describes TaskChampion server sync and supported storage backends. The current sync manual says Taskwarrior encrypts task data before sending it to a TaskChampion sync server; the server does not see unencrypted task data. Devices need the same encryption secret.

Keep that claim bounded. It concerns task data in the documented sync configuration, not the local database, your shell history, exported JSON, or every connection record. A server still has to route and store sync records. Do not translate encrypted content into an anonymity guarantee.

Avoid older advice that places a live Taskwarrior directory in a generic cloud-sync folder. The current high-level documentation explicitly says Taskwarrior 3's local database is not suitable for that approach and warns of corruption. Follow the version-specific synchronization system instead of copying a historical file-sharing recipe.

Best fit: command-line users who value scripting and can manage configuration and secrets. Poor fit: people who need an immediately accessible graphical interface or shared project boards without additional tooling.

Joplin: eligible open-source apps, if notes-first tasks are enough

Joplin's to-do documentation covers inline checklists, to-do notes, and alarms. Its apps run on Windows, macOS, Linux, Android, iOS, and the terminal. This is a notes-first option, not a claim that Joplin replaces every dedicated task-management feature.

The repository license states AGPL-3.0-or-later by default with directory-specific exceptions. That qualifies the apps here, but not every component under a blanket license claim. In particular, Joplin Server has a separate personal-use license with restrictions; do not describe the whole stack as uniformly AGPL.

You do not need Joplin Server to choose an open-source app with your own storage. The sync reference lists Nextcloud, WebDAV, S3, Dropbox, OneDrive, a filesystem target, and Joplin Cloud. Pick a backend whose operation and terms you accept.

E2EE must be enabled explicitly. The documentation recommends starting on one device, completing encryption and sync, then connecting the other devices. It warns that the encryption password cannot be recovered. That protects synced items under the documented model; it does not turn local app data or a plaintext export into an encrypted vault.

Best fit: people whose tasks belong alongside notes and reference material. Poor fit: users requiring a dedicated dependency planner or shared assignment workflow out of the box.

Maintenance evidence: current releases, not an audit badge

We checked these official latest non-prerelease records on October 28, 2026:

• Tasks.org 15.13, published October 14, 2026.
• Super Productivity v19.3.1, published October 25, 2026.
• Vikunja v2.7.1, published October 20, 2026.
• Taskwarrior v3.5.0, published August 16, 2026.
• Joplin v3.7.21, published September 25, 2026.

All five repositories were unarchived when checked. This is evidence of ongoing availability and release activity, not proof that any project has no vulnerabilities. Package stores and distribution repositories may ship different versions. Check the release and security notes for the version you actually install.

A practical privacy check before moving your real tasks

Use non-sensitive sample tasks for this checklist; these are suggested checks, not tests we claim to have performed on the shortlisted apps.

1. Verify license scope. Open the actual license, including any server or directory exceptions. Decide whether your requirement covers the client, the server, or both.
2. Try local work first. After initial setup, disconnect and check capture, editing, recurrence, and reminders. Do not assume a browser app is available before its first successful load.
3. Name the operator. Record the selected backend, its account requirement, and who controls the database and backups.
4. Check encryption before uploading. Confirm whether content encryption is enabled, where its secret lives, and which metadata remains visible. Use the documented setup, not a generic privacy slogan.
5. Check continuity and export. On a second device, inspect a sample task and its fields. Preserve an export carefully: a readable backup can undo the privacy benefit of encrypted sync.
6. Plan loss and recovery. Keep necessary secrets outside the device you might lose, and understand what cannot be recovered without them. Sync is not a substitute for a separately verified backup.

For selection based on local storage rather than licensing, use our private and local-first task app comparison. For the distinction between local data, sync payloads, and server-visible fields, read what leaves your device during private task sync.

Who Zero-Friction is for, and who it is not for

Zero-Friction Tasks is discussed outside the qualifying open-source shortlist. We have not verified a publicly distributed app source-and-license release that meets this article's eligibility rule. A private repository or an internal license file is not a substitute for publicly available source that readers can inspect and obtain under that license.

It can fit people who can accept that limitation and want local-first, no-account first use with a small capture surface, rather than a complete planning system. Optional encrypted sync is a separate decision. Its current implementation supports client-side encryption of task text and list names, but the service stores sync-code records and can derive the content key. Its public REST API receives the sync code and decrypts task text server-side for readable responses. This is not strict provider-blind E2EE; metadata and legacy/failure plaintext paths need separate consideration.

Choose one of the qualifying tools instead if public-source rights are non-negotiable, or if you need server ownership, time tracking, command-line automation, or shared project boards. Choose a documented provider-blind encrypted configuration if excluding the sync operator from content access is your deciding requirement. Do not choose Zero-Friction on the assumption that no account means no server processing.

If your priority is a smaller personal capture workflow and those boundaries fit your needs, Download Zero-Friction Tasks.