HAT (Heuristic Activity Tracker) Effective Date: May 26, 2026 Last Reviewed: May 26, 2026
This document governs your use of the HAT application (the compiled software). It is not the same as the software license. HAT’s source code is licensed separately under the GNU Affero General Public License version 3 (AGPL-3.0), the full text of which is included in the repository and governs what you may do with the source code.
These Terms of Service govern your use of the compiled, installed application — the experience of running HAT on your device. Both documents apply to you if you use HAT. Where they overlap, the AGPL governs source code matters and these Terms govern everything else.
Read this before using the app. Using HAT means you accept these terms. If you don’t accept them, don’t use the app.
In this document, the following terms have specific meanings:
“Application” means the HAT software in its compiled form, as installed on your Android device, including all updates and versions.
“Developer” means andromedvn, the sole author and maintainer of HAT, reachable at andromedvn@proton.me.
“You” or “User” means the individual installing or using the Application.
“Source Code” means the Kotlin and resource files that constitute HAT’s codebase, published at https://github.com/andromedvn/HAT under the AGPL-3.0 license.
“Data” means any information stored on your device by or through the Application, including app usage intervals, offline activity logs, preferences, and crash logs.
“Vault” means the HMAC-signed .zip archive exported by the Application’s backup feature.
“Usage Access” means the Android system permission (android.permission.PACKAGE_USAGE_STATS) that allows the Application to query app usage events from the operating system.
“OS Events” means the raw usage event data provided to the Application by Android’s UsageStatsManager API.
“Third-Party Libraries” means the open-source libraries the Application incorporates as dependencies, as listed in Section 9.
By installing, downloading, or using the Application, you confirm that:
If you do not agree to these Terms, you must not install or use the Application. Since HAT is free and open-source, you are always free to stop using it and uninstall it at any time.
Subject to these Terms, the Developer grants you a limited, non-exclusive, non-transferable, revocable license to install and use the Application on Android devices you personally own or control, for your own personal, non-commercial purposes.
This license does not include:
Source Code Rights: Your rights with respect to the Application’s source code are governed separately by the AGPL-3.0. If you fork, modify, or distribute the source code or binaries derived from it, AGPL-3.0 applies in full — including the requirement to make modified source code publicly available under the same license.
You may:
You may not use the Application to:
HAT’s data practices are described in full in the Privacy Policy. That document is incorporated into these Terms by reference. By using the Application, you also accept the Privacy Policy.
The short version: all data stays on your device. The Developer has no access to it. The Application has no internet permission and cannot transmit data to anyone.
This section exists because HAT’s output depends entirely on data provided by the Android operating system, and that data is imperfect. Understanding this limitation protects both you and the Developer.
The Application reconstructs your daily timeline by reading event data from Android’s UsageStatsManager API. This API is maintained by Google and the Android platform, not by the Developer. Its accuracy depends on:
The Developer makes no representation that the timeline produced by the Application is complete or accurate. The Application is a reconstruction tool, not an authoritative record. It produces a best-effort representation of your day based on available OS data.
Android permanently deletes usage event data on a rolling basis, typically retaining between two weeks and several months of history depending on the device and OS version. Once data has been deleted by the OS, it cannot be recovered. The Application’s archive worker mitigates this by saving data to local storage before the window closes, but it cannot recover data that was deleted before the Application was installed or before the archive worker ran.
Multiple Android device manufacturers implement battery optimization and background process management in ways that differ from Android’s documented behavior. On devices made by Xiaomi, Samsung, Huawei, OPPO, Vivo, and others, background workers (including HAT’s archive worker) may be delayed, skipped, or terminated regardless of their configured schedule. The Developer cannot control this behavior, cannot guarantee that the archive worker will run on any specific schedule on any specific device, and accepts no liability for data gaps caused by manufacturer-level process management.
The timeline HAT produces is intended for personal insight and planning. It is not a verified record of activity. You must not rely on HAT’s timeline data for legal proceedings, medical assessments, workplace time tracking, insurance claims, or any other context where an authoritative or legally binding record is required.
HAT is distributed exclusively through the following Official Channels:
Because HAT’s source code is published under the AGPL-3.0, any person may legally compile and redistribute modified or unmodified versions of the Application. The Developer exercises no control over third-party compilations, unofficial mirrors, APK-hosting sites, app stores other than F-Droid, or any forks.
The Developer assumes absolutely zero liability for any binary not obtained directly from an Official Channel. Without limitation, this covers:
If you obtained HAT from a source other than an Official Channel, the Developer cannot verify the integrity, safety, or behavior of your installation. These Terms of Service do not apply to non-official binaries and create no warranty, representation, or liability with respect to them.
To verify authenticity of a GitHub Release APK, compare its SHA-256 hash against the hash published in the corresponding GitHub Release page. F-Droid independently builds all APKs from published source code and is the recommended installation method for users who do not compile from source.
THE APPLICATION IS PROVIDED “AS IS” AND “AS AVAILABLE,” WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED.
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THE DEVELOPER EXPRESSLY DISCLAIMS ALL WARRANTIES, INCLUDING BUT NOT LIMITED TO:
This disclaimer applies regardless of whether the Developer was informed of the possibility of such defects.
If you are in a jurisdiction that does not permit implied warranties to be excluded, the above disclaimer applies to the fullest extent permitted by that jurisdiction’s laws.
TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, IN NO EVENT SHALL THE DEVELOPER BE LIABLE FOR ANY:
THIS LIMITATION APPLIES REGARDLESS OF THE THEORY OF LIABILITY — WHETHER CONTRACT, TORT (INCLUDING NEGLIGENCE), STRICT LIABILITY, OR OTHERWISE — AND REGARDLESS OF WHETHER THE DEVELOPER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
Because HAT is provided free of charge and the Developer receives no revenue from it, the Developer’s maximum aggregate liability to you for any claim arising out of your use of the Application is zero (₱0.00 / $0.00 USD / €0.00 EUR) or the minimum amount required by mandatory applicable law, whichever is greater.
Some jurisdictions do not allow the exclusion or limitation of incidental or consequential damages. In such jurisdictions, liability is limited to the greatest extent the law permits.
Because HAT has no cloud backup and the Developer cannot access your Data remotely, you are solely responsible for preserving your Data.
The Developer strongly recommends using the “Backup Master Vault” feature regularly, storing the exported vault in a safe location separate from your primary device, and verifying that vault files can be successfully imported before relying on them as a backup.
The Developer accepts no liability for Data loss caused by:
The Application incorporates the following third-party libraries. Each is licensed separately from HAT itself:
| Library | Publisher | License |
|---|---|---|
| AndroidX Core KTX | Google / The Android Open Source Project | Apache 2.0 |
| Jetpack Compose (BOM) | Google / AOSP | Apache 2.0 |
| Jetpack Navigation Compose | Google / AOSP | Apache 2.0 |
| AndroidX Lifecycle ViewModel | Google / AOSP | Apache 2.0 |
| AndroidX DataStore Preferences | Google / AOSP | Apache 2.0 |
| AndroidX WorkManager | Google / AOSP | Apache 2.0 |
| Material Icons Extended | Google / AOSP | Apache 2.0 |
| kotlinx.serialization | JetBrains | Apache 2.0 |
Full license texts for these libraries are available within the Application under Settings → Open Source Licenses.
These libraries are provided by their respective publishers under their respective terms. The Developer makes no warranty regarding their behavior, accuracy, or fitness for any purpose.
HAT’s Source Code is published under the GNU Affero General Public License version 3. The key practical implications are:
The full text of the AGPL-3.0 is included in the repository at LICENSE. If your intended use is not clearly covered, contact the Developer before proceeding.
The Application is not intended for children under the age of 13 (or under 18 in jurisdictions where that is the minimum age of digital consent). By using the Application, you confirm that you meet this age requirement, or that a parent or legal guardian has reviewed and consented to your use.
The Developer does not knowingly permit children under applicable age limits to use the Application and will take steps to restrict such use if it comes to the Developer’s attention.
The Application is developed in and distributed from the Philippines. As a software tool that contains standard cryptographic functionality (HMAC-SHA256 for vault integrity verification), it may be subject to export control regulations in various jurisdictions, including the U.S. Export Administration Regulations (EAR) and corresponding regulations in other countries.
You agree that you will not use or export the Application in violation of applicable export control laws. Specifically, you may not use the Application if:
Because HMAC-SHA256 is a standard cryptographic algorithm widely available in public libraries, it is not expected to trigger export licensing requirements under EAR’s License Exception ENC for open-source cryptographic components. If you are uncertain about your specific situation, consult legal counsel in your jurisdiction.
The Developer may update these Terms at any time. Updated Terms will be published at https://andromedvn.github.io/HAT/TERMS.html, and the “Effective Date” will be updated. Significant changes will be noted in the Application’s release notes.
Continued use of the Application after updated Terms have been published constitutes acceptance of the changes. If you do not accept updated Terms, stop using the Application and uninstall it.
You may stop using the Application and uninstall it at any time. There is no subscription to cancel, no account to close, and no data held remotely to request deletion of.
The Developer may terminate this license (and thus your right to use the Application under these Terms) if you materially breach these Terms and fail to remedy the breach within 30 days of receiving notice. Termination does not affect any rights or remedies the Developer may have at law.
You agree to defend, indemnify, and hold harmless the Developer from and against any claims, damages, losses, liabilities, costs, and expenses (including reasonable legal fees) arising from:
The Developer is not liable for any failure or delay in performing obligations under these Terms if such failure or delay arises from circumstances beyond reasonable control, including but not limited to: natural disasters, acts of government, changes in law or regulation, infrastructure failures (including the discontinuation of services on which HAT depends, such as the Android UsageStatsManager API), or other events that could not reasonably have been anticipated or prevented.
These Terms are governed by and construed in accordance with the laws of the Republic of the Philippines, without regard to its conflict of law principles.
For users in the European Economic Area, this choice of governing law does not deprive you of any protection afforded by the mandatory provisions of the consumer protection laws in your country of residence.
For users in the United States, you also retain any rights available to you under the mandatory consumer protection laws of your state.
Before initiating any formal dispute process, you agree to contact the Developer at andromedvn@proton.me and give at least 30 days for the parties to attempt to resolve the dispute informally. Most issues can be resolved this way.
If informal resolution fails, disputes arising out of or relating to these Terms or the Application shall be resolved as follows:
The Developer has designated the Philippines as the exclusive non-EU forum as a practical matter of access, cost, and fairness to a solo, zero-revenue developer. The effect is intentional: any party considering litigation over a free application with no commercial revenue should first weigh the practical cost and logistics of doing so in the Philippines. The Developer does not, however, waive the right to seek injunctive or other emergency equitable relief in any jurisdiction where necessary to prevent irreparable harm to intellectual property rights or to stop an ongoing violation of these Terms.
To the maximum extent permitted by applicable law, you agree that any dispute resolution will be conducted on an individual basis only, and not as a class, collective, or representative action.
If any provision of these Terms is found to be unenforceable or invalid under applicable law, that provision is modified to the minimum extent necessary to make it enforceable, or severed if modification is not possible. The remaining provisions of these Terms remain in full force and effect.
These Terms, together with the Privacy Policy and the AGPL-3.0 (as applicable to source code), constitute the entire agreement between you and the Developer regarding the Application. They supersede all prior agreements, representations, and understandings, whether written or oral, regarding the Application.
No waiver by the Developer of any breach of these Terms shall constitute a waiver of any subsequent breach.
For questions, concerns, or notices under these Terms:
Email: andromedvn@proton.me GitHub: https://github.com/andromedvn/HAT/issues
⚖️ These Terms were written to be clear and fair, not to trap you in legal language. If something here is ambiguous or seems unreasonable, raise it — contact information is above.