Android Custom ROMs

If you’re reading this post, chances are you’re new to the world of Custom ROMs For Android™. Am I right?


As a starter, it can be very overwhelming to grasp a bunch of new technical terms such as “bootloader”, “custom recovery”, “flashing ROM”, etc. Trust me, I’ve been there.

For me, it all started when I accidentally stumbled upon a thread in XDA while looking for tips to bring my old lagging smartphone back to life. And that opened the doors to this parallel dimension of Android-based operating system development to me.

Believe me, I was dead scared when finally flashing a Custom ROM on that smartphone. No prizes for guessing, the fear was not of failure, rather of rendering the phone useless in the process (bricking)!

Thankfully, it went well, and I was pleasantly surprised with the results and wondered why I didn’t know about this before.

If you share the dilemma, I can assure you that if I could flash a Custom ROM on my Android device, with my very limited knowledge, you can too.

Be warned that you may never again want to go back to using the stock OS provided by your smartphone manufacturer (yes!). Unless it’s a Pixel or OnePlus device maybe, will discuss later why.

Coming back to where we started, I’ll assume you’re a beginner if you’re reading this article (although even if you’re not, I’m glad you’re still with me).

Let us start taking baby steps into the world of custom ROMs for Android and understand what they are and what makes them so cool. Note that in this article we are not going to cover the processes involved, or try to understand the technicalities; we shall just focus on the basics.

What is Android?

Android is a touch-based operating system developed and maintained by Google for smartphones and tablets. It is based on a modified version of the Linux kernel.

What is Android Open Source Project (AOSP)?

Android Open Source Project (AOSP) is the official repository of Android OS maintained by Google where the source code in its purest form is available for anyone to download. The goal of AOSP is to provide an open-source framework for developers and manufacturers to build on while maintaining compatibility across various Android devices.

The source code is modified by various OEMs (such as Samsung and OnePlus) to add extra features, customization or performance optimization for their mobile devices.

Independent developers use the same source code to build feature-rich variants of the Android operating system for various devices. Let us discuss this part further.

What is a Stock ROM?

Stock ROM is the OS that comes pre-installed on a new Android device. The manufacturers build them by tweaking Android OS to give it a unique flavour. Popular examples: Samsung Experience and OxygenOS.

What is a Custom ROM?

In simple words, custom ROMs are firmware based on the Android operating system for mobile devices. Usually, they are built to enhance the user interface and/or add features on top of Android in its vanilla form.

Most of the custom ROMs are developed and maintained by individual Android developers or small teams. However, these are a few examples of corporates developing custom ROMs.

Why should you install Custom ROMs?

There are quite a few reasons why you may want to go for a custom ROM.

  • Stock Android: Most smartphone manufacturers ship their devices with custom skinned Android operating systems. And although some might like it, if you’re like me, you would prefer a clean, no-nonsense OS on your device. And since most custom ROMs retain the pure user interface of Android, it’s an obvious choice to go for them if you’re fond of simplicity.
  • Latest Android on older devices: Most smartphone manufacturers support their devices with OS upgrades through one or two years. That’s hardly one major version upgrade and few security updates. And then some companies do worse. So if you’re stuck with an outdated Android version on an old smartphone that no longer gets official updates from the manufacturer, you may give custom ROMs a serious thought. Plus, custom ROM developers are generally way quicker at pushing updates than most manufacturers.
  • Get rid of bloatware: When you buy a new smartphone, you will notice it comes with a bunch of pre-loaded apps, either from the manufacturer or a third party. Third-party app companies pay OEMs to ship their devices with their apps, which in turn helps bring down the overall smartphone prices for the consumers. These are usually the least used apps. What’s worse – most of them are installed as system apps, which means you cannot uninstall them if you want (although lately, I have observed a welcome change in this practice). Getting a custom ROM installed on your device makes sure you have a system clean of unwanted apps – which in turn means more storage space and less RAM wasted.
  • Added features/customization: Custom ROMs come with many added features not found in the stock OS of your device. And unlike those provided by the manufacturers, these are useful more often than not. Add to that the endless possibilities of customising the look and feel of your device the way you want, it’s a solid deal.
  • Regain control of your device: Most smartphones are deliberately underpowered by the manufacturers. This means you’re not getting the experience that the hardware on your device is capable of providing. Flashing a custom ROM and getting root access makes sure you get maximum performance from your device. Remember, you also paid for the hardware too when you bought the phone.

Why should you avoid Custom ROMs?

Despite the many advantages custom ROMs bring in, there are still a few points to reconsider:

  • Void warranty: Replacing the stock operating system of your device with a Custom ROM usually voids your warranty.
  • Possible damage to your device: The process of installing a Custom ROM is not for everyone. Go for it only if you want to take the challenge, and the risk of damaging your phone if something goes wrong.
  • Battery performance: It has been observed that Android devices provide the longest battery life on their stock skins. This is because they are optimised for the hardware and rigorously tested.
  • Hardware issues: Custom ROMs may at times be unstable on your device as they were not originally built to support your hardware. There may be abrupt restarts, frame drops or crashes. However, lately, I have noticed that the Custom ROM ecosystem has evolved a lot and many of these issues are no longer as frequent.

Are Custom ROMs safe to install?

Yes, custom ROMs are very safe to install as your daily driver. But there are a few things to keep in mind here:

  • Source: Download Custom ROMs only from respective official websites or XDA.
  • Instructions: Follow the installation instructions provided by the developer religiously. Often the developers don’t explain the process in-depth assuming you already know it. So, do thorough research before installing your first.
  • Expert help: Take expert help if needed. Watch tutorial videos on Youtube, call up an Android nerd you know or raise your query on the XDA forum so that the developer or the fellow members can help you out,

Who should install Custom ROMs?

First, be informed that installing custom ROMs comes with its share of risks as explained before. You need to be very sure you want this trade-off.

  • If your device is still under warranty, replacing the stock OS may void it. Read the warranty document first.
  • If your device is no longer under warranty but works flawlessly and you don’t see a reason to replace the OS, then don’t do it.
  • I would not recommend someone with limited technical know-how or a penchant for troubleshooting to install a Custom ROM on their own.
  • Yet, if you have the passion to try something different and are ready to do all the troubleshooting if things go wrong, just go for it.

Which devices don’t need a custom ROM?

This is very subjective. Any device can survive well without a custom ROM. But my personal opinion is, if your device is already running a near-stock version of Android, don’t go for a custom ROM.

So which devices in particular? Let’s see.

  • Pixel smartphones – They give a pure Android experience with added Pixel specific features and enhancements.
  • OnePlus smartphones – They run on OxygenOS, which gives a near-stock experience and is highly optimised for speed and performance.
  • Android One smartphones – The updates for these smartphones are pushed by Google itself as part of the Android One project.
  • Others – There are some manufacturers that at times launch devices with near-stock Android experience, without being part of the Android One project.

Are custom ROMs legal?

Absolutely. AOSP is open source. This means that any modifications made under the appropriate open source licence are completely legal as long as the new codes being added are not proprietary.

I’m glad you’re still with me in this learning journey. I hope we have been able to understand the basics of Custom ROMs, their merits and demerits and whether you really need to flash one on your device.

Next, I would advise you to read my article on the best custom ROMs for Android and figure out which one you like based on your needs.

Look, I know it can be daunting in the beginning, but isn’t most things in life the same?

If you have any queries or suggestions, please write in the comments. I would be happy to answer them as that helps me as much as you.

Thank you for reading.

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  1. From very long time I have been searching alot trying to know to find answer to my question is if I’m passionate to build a custom rom or stock rom by making modification to android what is the development process to start developing a an Os mostly I’m taking an example like Oxygen Os which is really gives us stock android experience which is very feature enriched with good requirements what a user need behalf of all those unused features from other companies giving us with bloatware and laggy performance
    So as whenever I looked into oxygen Os, miui, color Os, realme ui, One ui how they’re developed by OEMs how they differ from custom roms what is process to start developing such Os to give users the best experience as I always very curious to learn the process of development and design of such Roms no courses available no videos are there no much content available to resolve our doubts on this way of very confusing words between custom and stock roms so for me a Os is everything it’s heart of the mobile phone with Os it wouldn’t be possible to have such experience his has inspired me alot to start to learn custom roms or stock roms mainly I’m impressed with Oxygen Os I don’t know exactly what does we call it wheather stock rom or custom rom I was a bit confused before reading your article but now I’m kind of little clear to know this differences between them but I really loved your way of explaining on this for the first time I found it interesting useful content regarding this custom or stock rom
    So my question is how do I start developing a Os like Oxygen Os based on android is it possible what is the process should I follow how I learn how can I do it please I request you to help me out with this problem I’m going through from long time I’m still searching searching but never got my answer to start developing a Os based on android with good feature en-riched experience how do I learn to start developing using android so I can develop a rom on android I’m so passionate about this as it’s taken an tons of hours to spend but remained unanswered please guide me with the steps to reach there to carry out the process like how to be an stock rom developer yes I know it’s impossible for a single person to develop a Os but I believe nothing is impossible surely we gather PPL to keep continuing to serve PPL with better experience that I dream of I don’t know alot community please guide me even with the XDA community how to join and ask questions and get answered from different communities which help us to get answered and please also provide some sources to get much knowledge on developing a stock android as I was completely unware of it and so curious to work on my passion of developing a Os like Oxygen Os which is most of them favourite mine too after reading your blog I felt so happy to learn it’s so informative I hope I find my answers from you which has gave me a hope write this long note from pain
    The saddest part is no such content is available on internet where you can easily grasp it and start developing a stock rom I knew it’s not easy but still I as a student really feeling difficult to find it out that’s why no body is teaching me this to build a Os experience on android I hope you please help me in discovering my dream is only to develop to give best android Os experience like what Oxygen Os does please help in guiding and developing with all whole process from beginning steps everything thank you I’m eagerly waiting for your answer ? my ultimate aim is to build something a beautiful experience in the world mobile operating system please guide me I feel blessed ?

    1. Hi P Vamshi,

      Thank you for reading my blog. Unfortunately, I’m not the right person to guide you on how to build a custom ROM. I might learn it one day and write a guide right here on this blog 🙂 Until that happens, I would suggest a few things.
      1. You will find a lot of guides on this subject online, mostly on XDA Developers, YouTube and a few authority Android websites.
      2. Try to connect with the developers of the popular custom ROM projects. Probably one of them can spare a couple of hours to answer your queries.
      3. If you personally know an experienced Android developer, ask for help.

      I wish you the best in your learning journey!

    1. Hey Ali,

      The answer to your question is, yes and no.

      Yes, if there are no custom ROMs developed for your device, unfortunately, you’re out of luck.
      No, if you know how to build a custom ROM.


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