LineageOS is the best open source Android ROM for most old phones, because it supports far more devices than any alternative. LineageOS 23, based on Android 16, launched on October 11, 2025 for more than 100 devices, and LineageOS 24, based on Android 17, began rolling out to a selection of devices in October 2026. The catch is that your exact phone must be on its supported list and have an unlockable bootloader.
This guide compares LineageOS, /e/OS, GrapheneOS, CalyxOS, crDroid, and PixelOS for older hardware, explains how to check support, walks through the install process using the LineageOS wiki’s own steps, and covers the risks. It is not a substitute for the install guide for your specific phone.
Why Put a Custom ROM on an Old Phone
Manufacturers stop updating phones after a few years, and an unpatched phone becomes a security risk. A custom ROM can bring a newer Android version and current security patches to hardware the maker has abandoned. It can also remove preinstalled software. For an old phone that would otherwise go in a drawer or in the trash, a ROM is a way to keep it useful.
The trade-offs are real. Installing a ROM usually erases the phone, requires unlocking the bootloader, and carries risk if you flash the wrong files. The LineageOS wiki says wrong firmware can permanently damage the phone and that the install is at your own risk.
LineageOS: The Default Choice
LineageOS is a community-maintained, open source ROM. Android Authority reported that LineageOS 23 arrived on October 11, 2025 for more than 100 devices, based on Android 16’s initial stable release, and that LineageOS 21 development was ending with new devices going to 22.2. The LineageOS wiki’s page for the Pixel 4a (sunfish) lists versions from 18.1 through 23.0 as previously supported, with 23.2 (Android 16) as current.
LineageOS 24 and Android 17
Android Authority reported on October 11 to 12, 2026 that LineageOS 24, based on Android 17, adds browser-based WebUSB tools for ADB, Fastboot, Amlogic Burn, and Samsung Odin. Devices running Linux kernel 4.4 and 4.9 are limited to LineageOS 22.2. Official guides remain the recommended install method. As of October 17, 2026, the full list of LineageOS 24 devices had not been published on a page this article could check, so look up your own device on the wiki.
How Many Devices Are Supported
The wiki’s device list shows roughly 365 devices across about 30 vendors, with faded rows marking devices that are no longer officially supported. That count comes from a manual tally and includes unsupported entries, so treat it as approximate. LineageOS’s front page says only “more than 20 different manufacturers.”
What the FAQ Tells You
The LineageOS FAQ says builds usually cover no more than two versions, that volunteers maintain devices, and that support for the next Android version cannot be promised. It also says the project does not hide bootloader-unlock status, because “it isn’t our place to lie about security features.” That statement is relevant to banking apps, discussed below.
How to Check Whether Your Phone Is Supported
Go to wiki.lineageos.org/devices and use the Select a vendor menu. Find your phone by its marketing name or its codename. The Pixel 4a, for example, is sunfish. If your phone is listed with a current version, open its page. If its row is faded, official support has ended, and you should expect no new builds.
Step-by-Step: What an Install Looks Like
The following steps come from the LineageOS wiki’s Pixel 4a install guide. Other phones differ, so follow the guide for your own device.
- Install adb and fastboot on your computer and enable USB debugging on the phone.
- Boot the stock system once and test calls, SMS, Wi-Fi calling, and LTE, so you know what worked before.
- Remove Google accounts from the phone so factory reset protection does not lock you out.
- Update to the latest stock firmware.
- Enable OEM unlocking in Developer options, then run the fastboot flashing unlock command.
- Flash the dtbo image, then flash the Lineage Recovery boot image.
- In recovery, choose Apply update, then Apply from ADB, and use adb sideload to install the LineageOS zip.
- Sideload any add-ons before the first boot, then choose Reboot system now.
The wiki warns that unlocking the bootloader and the factory reset erase all data. Back up everything first.
Other Options Worth Knowing
/e/OS
The e Foundation’s device page lists 217 supported smartphones, many marked legacy or unsupported, with devices ranging from 2012 to 2024. The page does not name the Android version. /e/OS focuses on removing Google services from the phone. Check the device page for your model and its status.
GrapheneOS
GrapheneOS officially supports only Pixel phones, from the Pixel 6 through the Pixel 10a (22 models), and strongly recommends eighth-generation Pixels and later. It deliberately does not support other hardware. Installation uses WebUSB, which the project recommends, or the command line. It is an excellent choice for a Pixel 6 or newer and a non-starter for anything else.
CalyxOS
CalyxOS announced a hiatus on August 1, 2025, after founder Nicholas Merrill and tech lead Chirayu Desai left. A later notice says it returned with release 7.2.2.0 on July 2, 2026, according to LinuxFr, and Wikipedia lists release 7.2.5.20 on September 12, 2026. Support for the Fairphone 6 was added in September 2026. Describe it as paused for about a year and now back under new maintainers, and check its device list before relying on it.
crDroid and PixelOS
crDroid describes itself as built upon LineageOS and does not guarantee support for any device. PixelOS is AOSP-based, and its blog shows a September 2026 update post and an August 2026 post titled “Welcome, Android 17.” Neither page listed supported devices, so check each project’s site.
Replicant
The Replicant site blocked automated access, so its current status could not be verified for this article.
Google’s Developer Verification and Custom ROMs
Google announced developer verification rules for Android apps. According to Android Developers, protections start on September 30, 2026 in Brazil, Indonesia, Singapore, and Thailand on certified devices running Android 7 and later, with a global rollout planned for 2027 and beyond. An advanced flow exists for power users, and limited distribution accounts allow up to 20 devices with no ID or fee.
Republic World reported on July 6, 2026 that LineageOS rejected the new sideloading rules and said it does not ship Google’s app suite or take part in certification, so the rule does not technically apply to it. The report notes a gap: a sideloaded third-party Google apps package could theoretically include verification. This comes from a secondary source, so confirm with LineageOS’s own statements.
Risks to Weigh Before You Flash
Data Loss
Unlocking the bootloader wipes the phone. Back up photos, messages, and app data first.
Bricking
The LineageOS wiki warns that the wrong firmware can permanently damage the phone. Follow your device’s guide exactly and use only the files it lists.
Banking and Payment Apps
Some apps check the device’s security state and may refuse to run on an unlocked bootloader or a custom ROM. The LineageOS pages reviewed did not address this directly, but the FAQ’s statement that the project will not hide bootloader-unlock status suggests that apps checking for it may notice. Test your essential apps before you rely on the phone.
Warranty
Unlocking a bootloader may void a manufacturer’s warranty. The LineageOS pages reviewed did not say, so check your maker’s terms. For an old phone, the warranty has often expired anyway.
Unofficial Builds
Never flash a ROM from a random website or forum post. Use official downloads from the project and verify that your device is listed.
Which ROM to Choose
For the Widest Device Support
LineageOS. Check the wiki first.
For Strong Security on a Pixel
GrapheneOS, on a Pixel 6 or newer.
For a Google-Free Experience With Support Pages for Many Phones
/e/OS, after checking your model’s listing.
For Experimenting
crDroid or PixelOS, understanding that device support varies.
A Safer Way to Start: Practice on a Spare Phone
If you have never flashed a ROM, do not make your first attempt on the phone you depend on. The LineageOS wiki’s warnings are blunt: unlocking and the factory reset erase all data, wrong firmware can permanently damage the phone, and installing is at your own risk. A spare or retired device lets you learn the tools, adb and fastboot, without consequences. Read the entire install page for your device before typing a command, and keep a record of which stock firmware version you started from.
Questions to Ask Before Choosing a ROM
Is my exact model on the official list? Who maintains it, and when was the last build? Does the project explain how to go back to stock? Does it ship Google apps, and if not, how will I get the apps I need? Does the ROM’s project page state its security update policy? The LineageOS FAQ says builds usually cover no more than two versions and that volunteers maintain devices, so the maintainer question matters. A device with an active maintainer and recent builds is a better bet than one with a faded row on the wiki.
Keeping an Old Phone Secure After the Install
Installing a ROM is not the end. Updates arrive from volunteers, so check how often your device receives builds, and update when they appear. The LineageOS FAQ says builds usually cover no more than two Android versions, so a phone whose maintainer has stopped will eventually fall behind. Keep the bootloader decision in mind too: an unlocked bootloader is a security trade-off, and the FAQ confirms LineageOS does not hide that status. Use a strong screen lock, and install apps only from sources you trust.
What to Do If the Install Fails
Stop and do not improvise. Read the error message, and compare it with the troubleshooting information on your device’s wiki page. If the phone will not boot, the recovery and fastboot modes described in the install guide are usually the way back, which is why the guide asks you to confirm stock firmware first. Ask for help on the project’s official channels, and never flash files from an unofficial source to fix a problem.
Frequently Asked Questions
What is the best custom ROM for an old Android phone?
LineageOS is the best-supported choice for most old phones, if your model is on its device list.
Is LineageOS safe?
It is open source and community-maintained. The main risks come from the install process, including data loss and flashing the wrong files, and from apps that check bootloader status.
Can I install GrapheneOS on any old phone?
No. It supports only Pixel phones from the Pixel 6 through the Pixel 10a.
Is CalyxOS dead?
No. It paused in August 2025 and resumed in July 2026 under new maintainers, according to its own notices and later reports.
Will a custom ROM make my phone faster?
The sources reviewed make no performance claims. Updates mainly bring newer Android versions and security patches.
References and Sources
LineageOS Wiki, “Devices”: https://wiki.lineageos.org/devices/
LineageOS Wiki, “Install LineageOS on sunfish”: https://wiki.lineageos.org/devices/sunfish/install
LineageOS Wiki, “FAQ”: https://wiki.lineageos.org/faq
Android Authority, “LineageOS 23 release”: https://www.androidauthority.com/lineageos-23-release-3604073/
Android Authority, “LineageOS 24 based on Android 17”: https://androidauthority.com/lineageos-24-android-17-3721683
Android Developers, “Android developer verification”: https://developer.android.com/developer-verification
Republic World, “LineageOS rejects Google’s new sideloading rules”: https://www.republicworld.com/tech/lineageos-rejects-googles-new-sideloading-rules-vows-to-keep-android-open-2026-07-06-131369
GrapheneOS, “Frequently Asked Questions”: https://grapheneos.org/faq
GrapheneOS, “Install”: https://grapheneos.org/install/
e Foundation, “Devices”: https://doc.e.foundation/devices
CalyxOS, “A letter to our community”: https://calyxos.org/news/2025/08/01/a-letter-to-our-community/
LinuxFr, “CalyxOS est de retour”: https://linuxfr.org/news/calyxos-est-de-retour
crDroid, “crDroid Android”: https://crdroid.net/
PixelOS, “PixelOS Blog”: https://blog.pixelos.net/
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