[Why we recommend GrapheneOS over CalyxOS :material-arrow-right-drop-circle:](https://blog.privacyguides.org/2022/04/21/grapheneos-or-calyxos/ ""){.md-button}
We recommend installing one of these custom Android operating systems on your device, listed in order of preference, depending on your device's compatibility with these operating systems.
GrapheneOS supports [Sandboxed Google Play](https://grapheneos.org/usage#sandboxed-google-play), which runs [Google Play Services](https://en.wikipedia.org/wiki/Google_Play_Services) fully sandboxed like any other regular app. This means you can take advantage of most Google Play Services, such as [push notifications](https://firebase.google.com/docs/cloud-messaging/), while giving you full control over their permissions and access, and while containing them to a specific [work profile](os/android-overview.md#work-profile) or [user profile](os/android-overview.md#user-profiles) of your choice.
DivestOS has automated kernel vulnerability ([CVE](https://en.wikipedia.org/wiki/Common_Vulnerabilities_and_Exposures)) [patching](https://gitlab.com/divested-mobile/cve_checker), fewer proprietary blobs, and a custom [hosts](https://divested.dev/index.php?page=dnsbl) file. Its hardened WebView, [Mulch](https://gitlab.com/divested-mobile/mulch), enables [CFI](https://en.wikipedia.org/wiki/Control-flow_integrity) for all architectures and [network state partitioning](https://developer.mozilla.org/en-US/docs/Web/Privacy/State_Partitioning), and receives out-of-band updates. DivestOS also includes kernel patches from GrapheneOS and enables all available kernel security features via [defconfig hardening](https://github.com/Divested-Mobile/DivestOS-Build/blob/master/Scripts/Common/Functions.sh#L758). All kernels newer than version 3.4 include full page [sanitization](https://lwn.net/Articles/334747/) and all ~22 Clang-compiled kernels have [`-ftrivial-auto-var-init=zero`](https://reviews.llvm.org/D54604?id=174471) enabled.
DivestOS implements some system hardening patches originally developed for GrapheneOS. DivestOS 16.0 and higher implements GrapheneOS's [`INTERNET`](https://developer.android.com/training/basics/network-ops/connecting) and SENSORS permission toggle, [hardened memory allocator](https://github.com/GrapheneOS/hardened_malloc), [exec-spawning](https://blog.privacyguides.org/2022/04/21/grapheneos-or-calyxos/#additional-hardening), [JNI](https://en.wikipedia.org/wiki/Java_Native_Interface) [constification](https://en.wikipedia.org/wiki/Const_(computer_programming)), and partial [bionic](https://en.wikipedia.org/wiki/Bionic_(software)) hardening patchsets. 17.1 and higher features GrapheneOS's per-network full [MAC randomization](https://en.wikipedia.org/wiki/MAC_address#Randomization) option, [`ptrace_scope`](https://www.kernel.org/doc/html/latest/admin-guide/LSM/Yama.html) control, and automatic reboot/Wi-Fi/Bluetooth [timeout options](https://grapheneos.org/features).
DivestOS uses F-Droid as its default app store. Normally, we would recommend avoiding F-Droid due to its numerous [security issues](#f-droid). However, doing so on DivestOS isn't viable; the developers update their apps via their own F-Droid repositories ([DivestOS Official](https://divestos.org/fdroid/official/?fingerprint=E4BE8D6ABFA4D9D4FEEF03CDDA7FF62A73FD64B75566F6DD4E5E577550BE8467) and [DivestOS WebView](https://divestos.org/fdroid/webview/?fingerprint=FB426DA1750A53D7724C8A582B4D34174E64A84B38940E5D5A802E1DFF9A40D2)). We recommend disabling the official F-Droid app and using [Neo Store](https://github.com/NeoApplications/Neo-Store/) with the DivestOS repositories enabled to keep those components up to date. For other apps, our recommended methods of obtaining them still apply.
When purchasing a device, we recommend getting one as new as possible. The software and firmware of mobile devices are only supported for a limited time, so buying new extends that lifespan as much as possible.
Avoid buying phones from mobile network operators. These often have a **locked bootloader** and do not support [OEM unlocking](https://source.android.com/devices/bootloader/locking_unlocking). These phone variants will prevent you from installing any kind of alternative Android distribution.
Be very **careful** about buying second hand phones from online marketplaces. Always check the reputation of the seller. If the device is stolen, there's a possibility of [IMEI blacklisting](https://www.gsma.com/security/resources/imei-blacklisting/). There is also a risk involved with you being associated with the activity of the previous owner.
- Do not buy devices that have reached or are near their end-of-life, additional firmware updates must be provided by the manufacturer.
- Do not buy preloaded LineageOS or /e/ OS phones or any Android phones without proper [Verified Boot](https://source.android.com/security/verifiedboot) support and firmware updates. These devices also have no way for you to check whether they've been tampered with.
- In short, if a device or Android distribution is not listed here, there is probably a good reason. Check out our [forum](https://discuss.privacyguides.net/) to find details!
Google Pixel phones are the **only** devices we recommend for purchase. Pixel phones have stronger hardware security than any other Android devices currently on the market, due to proper AVB support for third-party operating systems and Google's custom [Titan](https://security.googleblog.com/2021/10/pixel-6-setting-new-standard-for-mobile.html) security chips acting as the Secure Element.
Secure Elements like the Titan M2 are more limited than the processor's Trusted Execution Environment used by most other phones as they are only used for secrets storage, hardware attestation, and rate limiting, not for running "trusted" programs. Phones without a Secure Element have to use the TEE for *all* of those functions, resulting in a larger attack surface.
The installation of GrapheneOS on a Pixel phone is easy with their [web installer](https://grapheneos.org/install/web). If you don't feel comfortable doing it yourself and are willing to spend a bit of extra money, check out the [NitroPhone](https://shop.nitrokey.com/shop) as they come preloaded with GrapheneOS from the reputable [Nitrokey](https://www.nitrokey.com/about) company.
- If you're after a bargain on a Pixel device, we suggest buying an "**a**" model, just after the next flagship is released. Discounts are usually available because Google will be trying to clear their stock.
- Consider price beating options and specials offered at physical stores.
- Look at online community bargain sites in your country. These can alert you to good sales.
- Google provides a list showing the [support cycle](https://support.google.com/nexus/answer/4457705) for each one of their devices. The price per day for a device can be calculated as: $\text{Cost} \over \text {EOL Date}-\text{Current Date}$, meaning that the longer use of the device the lower cost per day.
We recommend a wide variety of Android apps throughout this site. The apps listed here are Android-exclusive and specifically enhance or replace key system functionality.
- Using a [Trust On First Use (TOFU)](https://en.wikipedia.org/wiki/Trust_on_first_use) model between an *auditor* and *auditee*, the pair establish a private key in the [hardware-backed keystore](https://source.android.com/security/keystore/) of the *Auditor*.
- The *auditor* can either be another instance of the Auditor app or the [Remote Attestation Service](https://attestation.app).
- The *auditor* records the current state and configuration of the *auditee*.
- Should tampering with the operating system of the *auditee* happen after the pairing is complete, the auditor will be aware of the change in the device state and configurations.
No personally identifiable information is submitted to the attestation service. We recommend that you sign up with an anonymous account and enable remote attestation for continuous monitoring.
If your [threat model](basics/threat-modeling.md) requires privacy, you could consider using [Orbot](tor.md#orbot) or a VPN to hide your IP address from the attestation service. To make sure that your hardware and operating system is genuine, [perform local attestation](https://grapheneos.org/install/web#verifying-installation) immediately after the device has been installed and prior to any internet connection.
- Auto removal of [Exif](https://en.wikipedia.org/wiki/Exif) metadata (enabled by default)
- Use of the new [Media](https://developer.android.com/training/data-storage/shared/media) API, therefore [storage permissions](https://developer.android.com/training/data-storage) are not required
- Microphone permission not required unless you want to record sound
GrapheneOS's app store is available on [GitHub](https://github.com/GrapheneOS/Apps/releases). It supports Android 12 and above and is capable of updating itself. The app store has standalone applications built by the GrapheneOS project such as the [Auditor](https://attestation.app/), [Camera](https://github.com/GrapheneOS/Camera), and [PDF Viewer](https://github.com/GrapheneOS/PdfViewer). If you are looking for these applications, we highly recommend that you get them from GrapheneOS's app store instead of the Play Store, as the apps on their store are signed by the GrapheneOS's project own signature that Google does not have access to.
The Google Play Store requires a Google account to login which is not great for privacy. You can get around this by using an alternative client, such as Aurora Store.
Aurora Store does not allow you to download paid apps with their anonymous account feature. You can optionally log in with your Google account with Aurora Store to download apps you have purchased, which does give access to the list of apps you've installed to Google, however you still benefit from not requiring the full Google Play client and Google Play Services or microG on your device.
For apps that are released on platforms like GitHub and GitLab, you may be able to add an RSS feed to your [news aggregator](/news-aggregators) that will help you keep track of new releases.
On GitHub, using [Secure Camera](#secure-camera) as an example, you would navigate to its [releases page](https://github.com/GrapheneOS/Camera/releases) and append `.atom` to the URL:
On GitLab, using [Aurora Store](#aurora-store) as an example, you would navigate to its [project repository](https://gitlab.com/AuroraOSS/AuroraStore) and append `/-/tags?format=atom` to the URL:
If you download APK files to install manually, you can verify their signature with the [`apksigner`](https://developer.android.com/studio/command-line/apksigner) tool, which is a part of Android [build-tools](https://developer.android.com/studio/releases/build-tools).
==We do **not** currently recommend F-Droid as a way to obtain apps.== F-Droid is often recommended as an alternative to Google Play, particularly in the privacy community. The option to add third-party repositories and not be confined to Google's walled garden has led to its popularity. F-Droid additionally has [reproducible builds](https://f-droid.org/en/docs/Reproducible_Builds/) for some applications and is dedicated to free and open-source software. However, there are [notable problems](https://privsec.dev/posts/android/f-droid-security-issues/) with the official F-Droid client, their quality control, and how they build, sign, and deliver packages.
Due to their process of building apps, apps in the official F-Droid repository often fall behind on updates. F-Droid maintainers also reuse package IDs while signing apps with their own keys, which is not ideal as it gives the F-Droid team ultimate trust.
Other popular third-party repositories such as [IzzyOnDroid](https://apt.izzysoft.de/fdroid/) alleviate some of these concerns. The IzzyOnDroid repository pulls builds directly from GitHub and is the next best thing to the developers' own repositories. However, it is not something that we can recommend, as apps are typically [removed](https://github.com/vfsfitvnm/ViMusic/issues/240#issuecomment-1225564446) from that respository when they make it to the main F-Droid repository. While that makes sense (since the goal of that particular repository is to host apps before they're accepted into the main F-Droid repository), it can leave you with installed apps which no longer receive updates.
That said, the [F-Droid](https://f-droid.org/en/packages/) and [IzzyOnDroid](https://apt.izzysoft.de/fdroid/) repositories are home to countless apps, so they can be a useful tool to search for and discover open-source apps that you can then download through Play Store, Aurora Store, or by getting the APK directly from the developer. It is important to keep in mind that some apps in these repositories have not been updated in years and may rely on unsupported libraries, among other things, posing a potential security risk. You should use your best judgement when looking for new apps via this method.
In some rare cases, the developer of an app will only distribute it through F-Droid ([Gadgetbridge](https://gadgetbridge.org/) is one example of this). If you really need an app like that, we recommend using [Neo Store](https://github.com/NeoApplications/Neo-Store/) instead of the official F-Droid app to obtain it.
## Criteria
**Please note we are not affiliated with any of the projects we recommend.** In addition to [our standard criteria](about/criteria.md), we have developed a clear set of requirements to allow us to provide objective recommendations. We suggest you familiarize yourself with this list before choosing to use a project, and conduct your own research to ensure it's the right choice for you.
!!! example "This section is new"
We are working on establishing defined criteria for every section of our site, and this may be subject to change. If you have any questions about our criteria, please [ask on our forum](https://discuss.privacyguides.net/latest) and don't assume we didn't consider something when making our recommendations if it is not listed here. There are many factors considered and discussed when we recommend a project, and documenting every single one is a work-in-progress.
