What is the 12-Factor App Development Methodology and why use it?

12 factor application

To avoid apparent setbacks in Software Development, engineers keep reinventing the wheel time and again. However, the process of developing a bug-free, scalable, high-performing, and enterprise-level web app needs much more than that. For example, a tried and tested outline like the 12 Factor App.

Now, what does the term “Twelve-Factor App” mean in software development, from where does it come, and what are 12-Factor App benefits? Let’s find out.

What is the 12 Factor App Methodology?

With the rise of flexible working, SaaS has grown rapidly to become one of the world’s most famous software delivery models, and there is no sign of slowing down. However, building a Software-as-a-Service application is no less than controlling a complex monster.

You need to define every process with utmost precision, from coding to deployment to managing the databases, and so on. All while keeping in mind the high scalability and performance desired from the final solution.

Therefore, to help you en-route, you need a robust framework that keeps you in line with the initial requirements and lets you develop a high-quality, resilient, scalable, and maintainable SAAS application following the right set of Software Development Principles. One such framework, outline, set of guidelines, or rule-book is called the Twelve Factor App.

The 12-Factor methodology can help you avoid headaches associated with building long-term and large-scale cloud-based software projects by following twelve simple rules:

What are the 12 factor application methodologies

Though the 12 Factor App methodology doesn’t eliminate the complexity of SAAS Application Development, it provides a framework to organize the entire project ensuring a healthy development environment and an optimized web experience.

The 12 Factor App History

In 2012, developers at Heroku invented the Twelve-Factor Methodology to help build scalable SAAS apps. The programmers that wrote these have developed and deployed thousands of apps and created this rule-book keeping the following goals in mind:

  • To avoid the cost of software erosion
  • To control the dynamics of organic growth of an app over time
  • To Improve collaboration between developers working on same app’s codebase
  • To raise awareness of systemic problems that occur in modern app development

Today, every Software Development Company building apps that run as a service or ops engineers who manage or deploy such apps can refer to these principles for improving processes and workflow.

The 12-Factor App Methodology Principles

The Twelve Factor App methodology is based on twelve strict rules that act as a building block for developing and deploying SAAS applications. These are also called 12 Factor App Principles and are listed below in detail:

1. CodeBase

The first principle of the Twelve-Factor Apps is that every application should have just a single codebase. However, multiple deployments are possible.

If an app has multiple codebases, it is a violation of the 12 Factor Application methodologies, and in such case, the app becomes a distributed system. But, each component in a distributed system is an app and can comply with the 12-Factors.

12 Factor app says every app should have single codebase

As per the 12 Factor Methodology, a deploy is a running instance of the app, for example, production, staging, or developer’s copy. Though different versions can be active in each deployment, the codebase shall remain the same across all deploys.

2. Dependencies

The second 12-Factor App Dependencies principle says that your app might depend on external packages or libraries. Still, you should never think that these will be available on the target system. Therefore, an app must always declare all the dependencies and their correct versions explicitly.

A Twelve Factor Application never depends on the system-wide packages’ implicit existence and declares all dependencies using a dependency declaration manifest. Also, it uses a dependency isolation tool to ensure no implicit dependencies are there in the system.

For example, while working on Python, you can use Pip for declaration and VirtualENV for isolation. No matter what tools or tech stack you use, to comply with 12 Factor App Principles, dependency declaration and isolation must be used together.

One of the significant 12 Factor App benefits that it offers is a simplified setup for new app developers. They can simply check the app’s codebase using their own machines just by having the language runtime, and dependency manager installed.

3. Config

Because an app’s config varies between several deploys, storing it as constants in code is a violation of 12 Factor. Please note that the “config” here doesn’t mean the app’s internal config as it doesn’t vary between deploys and is best stored in code.

An app that complies with 12 Factors, store config in environment variables (env vars or env). The reason is env is easy to change between the deploys without having to change the code. These environment variables are never grouped in a 12 Factor App but are managed independently for each deploy. The benefit of using this approach shows up when the app naturally expands into more deploys during its lifetime as this model scales up easily.

4. Backing Services

In a 12-Factor App, Backing Services means any attached services that the app consumes over the network for executing its normal operations. These services can either be locally-managed or can be some third parties.

For example, datastores like MySQL, caching systems like Memcached, or binary asset services like Amazon S3. An app that complies with 12 Factor methodology makes no distinction between these services and treats all like attached resources accessed using a URL or other credentials stored in config.

The 12 Factor rule says that if the location or connection details of such service changes, you shouldn’t need to make changes in the code. These details should be available in the config.

Twelve Factor Apps Backing Services

These services can be attached or detached from deploys quickly. For example, if an app’s database is not working correctly due to any issue; the developer should be able to spin up a new database server restored from a recent backup without any code changes.

5. Build, Release, Run

Build, release, and run are three important stages of the Software Development Life Cycle. Let’s see what these stages are all about in the context of the 12 Factor apps:

Build Release Run

  • Build: It converts the code repo into an executable bundle of code called build, along with fetching vendor dependencies.
  • Release: It takes the build and combines it with the current config of deploy. Therefore, this stage gives us build and config ready for execution.
  • Run: It runs the app in an execution environment.

The Twelve Factor App rule says that there should be a strict separation between these stages to avoid code break or any other risk. This separation can be done using many modern tools, making maintaining the entire system as easy as possible.

6. Processes

An app is executed in an execution environment as a collection of one or more processes. And 12 Factor processes are stateless and share nothing.

Therefore, any data that is required time and again must be stored in a stateful backing service. A 12 Factor Application never expects that anything cached will be there in the future for new requests. The principle focuses on increasing the system’s overall stability and scalability without making any impact on the actual application.

7. Port-Binding

A Twelve-Factor App acts as a standalone service and doesn’t require runtime injection of a webserver in an execution environment to make a web-facing service.

It means that a web app that complies with Twelve-Factor principles is self-contained and doesn’t require any running or existing app server for the execution. The web application exports HTTP as a service by binding to a port and listens to coming in requests.

8. Concurrency

This 12 Factor principle is related to scaling the application, and it says you should deploy more copies of your application instead of making your app larger. Basically, it supports horizontal scaling of an app instead of vertical scaling.

Using this 12-Factor rule, web developers can design their apps to handle diverse workloads by giving each type of work to a particular process type. The model indeed proves very helpful when it comes time to scale an app.

Concurrency Rule of 12 Factor Applications

This horizontally scalable and self-contained nature of 12 Factor App processes implies adding more concurrency is a reliable and easy option.

9. Disposability

The 12 Factor App disposability principle focuses on maximizing an application’s robustness with fast startup and graceful shutdown. It states that an app’s processes are disposable, which means:

  • These can start and end at a moment’s notice
  • Are robust against sudden failure or app crash
  • Can shut down gracefully

This provides various benefits to the app, like rapid deployment of code, fast elastic scaling, more agility for the release process, and robust production deploys.

10. Dev/Prod Parity

The Twelve Factor App Methodology suggests that the development, staging, and production of an app should be as similar as possible to ensure that anyone can understand and release it. An app that complies with 12 Factors is designed for continuous deployment by keeping the following gaps as minimum as possible:

  • The Time Gap: A developer can write a code and deploy it hours or just a few minutes later.
  • The Personnel Gap: Programmers or owners of the code should be closely involved in deploying it.
  • The Tool Gap: The tools used for development and production should be as similar as possible.

This eliminates the risk of bugs in a specific environment and makes processes organized and simple.

11. Logs

The rule suggests treating logs as event streams. Logging is crucial for keeping a check on the behavior of your application. However, 12-Factor apps shouldn’t be concerned with the management of these logs.

Instead, it should treat log entries as event streams that are routed to a separate service for analysis and archival. The app logs will be written as standard outputs, but the execution environment will take care of its storage, capture, and archival. This system provides greater flexibility and power for introspecting the app’s behavior over time.

12. Admin Processes

Though this rule is not related to developing services, it is more about managing your application but is still essential. It says that apps should run management or admin tasks in an identical environment as the app’s regular and long-running processes.

Also, it suggests using the execution environment’s built-in tool to run those scripts on the production server.

While listed above were twelve strong principles for Web App Development, there is something worth considering beyond the 12 Factor App methodology for building software.

Web apps are the basic building blocks of an enterprise, and nothing should be left unconsidered while building these to ensure scalability and security. Listed below are some additional points beyond Twelve Factor Apps that you should keep in mind during app development and launch:

App Security is of Utmost Importance: In an enterprise ecosystem, you must address all dimensions of security from day one when you start writing your app’s code.

Best practices to ensure security in an app includes using TLS (Transport layer security) to secure data in transit and using API keys to ensure authentication and authorization. No doubt that the realm of security is broad, but you need to take care of all things (like operating systems, firewalls, networks, database security, and more) to build a secure microservice.

The API First Approach: If you adopt the principle that all apps are backing services and they should be designed as APIs-first, you can develop a system that is free to grow, scale, and adapt to new demands and load. This means what you are creating is an API to be consumed by client apps and services.

While building a SaaS application, if you follow all the above-mentioned best practices or principles, you can build scalable, independent, and robust enterprise applications with ease and top-notch security. Let’s now check who uses factor 12 and what are its significant business benefits.

Who Uses 12 Factor?

The 12 Factor methodology is a rule-book for creating cloud-ready applications, and several leading companies like Amazon, Heroku, and Microsoft follow its listed principles. Some widely-used frameworks like Magento and Spring Boot also credit 12 Factors as a part of their design.

These principles help design and maintain a robust and modern app architecture for cloud web apps ensuring the timely release of new features and fixes. It lets you build cloud-ready 12 factor architecture by fulfilling all cloud-based requirements.

Software developers developing the following can follow these guidelines to ensure maximum automation and agility by minimizing divergence between development and deployment:

But, 12 Factor is certainly not a solution for every company out there that is building software. All you need to analyze is your business problems and find whether 12 Factor has a solution for it or not. The right way to apply a 12-Factor app for microservices is by prioritizing your team’s needs and the problem at hand.

3 Business Benefits of Twelve Factor Apps

While the 12 Factor methodology helps developers develop a robust and resilient web app through continuous deployment, it also offers many business benefits.

Elasticity: Web apps that comply with the 12-Factor methodology can grow and shrink as per the need. These apps can scale-out when there is high traffic and scale-in when the traffic is low, saving you infrastructure costs. Also, you can scale such apps without making significant changes to the 12 factor application architecture.

Modularity: A Twelve Factor App is designed mainly for developing modern and containerized cloud environments from scratch. Each component is tailored to cloud deployment flexibility in such an app while creating a standard for every third-party developer to follow.

Information Security: The 12 Factor Methodology says that your credentials or any other confidential information should not be in code repo but in the application’s environment. This ensures security and also enforces segregation of duties.

The 12 Factor principles create a more flexible and straightforward approach to develop cloud apps and microservices. Using these principles, businesses can build web apps that offer a positive user experience using virtual environments for higher availability.


In the last few years, the 12-Factor App Principles has helped several web apps, platforms, and frameworks climb the ladder of success.

For cloud app development and DevOps, this rule-book has worked so well that many of the principles listed in it are now considered as a blueprint for building portable, resilient, scalable, and maintainable solutions. However, it isn’t “correct” for everyone.

Whether it is for you or not depends on your business needs. If your software requirements demand you to deviate from any of the principles listed-above – it is completely alright. The only condition is you should know why you are deviating and what will be its consequences.

By considering these 12 Factor App design principles early in your software development process, you can architect robust enterprise solutions. Now that you know what does 12 Factor App indicate let us know in the comments below its most significant application for your business.

Build 12 factor apps with Net solutions

Manish Garg

About the Author

Manish Garg is a Senior Technical Project Manager at Net Solutions. He handles project deliveries pertaining to Java and has an active involvement in the pre-sales functions. He has a rich experience in product development and maintenance. In his free time, he loves reading books. Also, he is a nemophilist looking for new places to explore during vacations.

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