Top 6 Software Development Life Cycle (SDLC) Models & Methodologies

AgileTech Vietnam
9 min readJul 31, 2020


software development life cycle SDLC software development methodology software development process software development model

Software development life cycle is not the new concept. We all use different software development methodologies to make our lives easier… For example, using live streaming music, ride hailing taxi or location-based application has changed human behavior for good. But have you wondered how these apps came to be? How to turn your mobile app idea into reality?

Well, if you have, you need to understand the Software Development Life Cycle or SDLC. It is an extremely useful tool for development leaders who need to undertake the software development process.

In this article, we will discover many kinds of software development life cycle models as well as their strengths and weaknesses. We will also provide you with a helpful guideline to determine when best to use each one of them.

But before getting into that, let’s first find out the basic process of software development life cycle.

★ Read also: How much money can you earn with free apps?

What are Software Development Life Cycle (SDLC) Phases?

Generally, software development life cycle is about breaking down your software development workflow into essential steps. Let’s understand what the steps of SDLC methodologies are through an example.

SDLC Methodologies

Imagine if you need to have a mobile app built. This process would need multiple steps. Then, software development life cycle is used to help development team optimize their workflow, make it scalable and ensuring quality at the same time.

  • This software development process guides you through the project from start to finish.
  • It highlights where your workflow is weakest or where the greatest risks lie.
  • If the involvement of other teams or stakeholders is required, their impact on timelines or approvals can be planned for.
software development life cycle stages SDLC phase

Any software engineer should have enough knowledge to choose the right software development life cycle models. So that, to use it effectively, let’s see how SDLC can speed up the development process and even reduce costs:

1. Requirement analysis

At first stage, all you need to do is about deciding what you’re going to develop. If you developing for clients, this will discuss their needs, goals, and expectations. During the first phase of software development life cycle, outline the following:

  • Answer questions such as: How will the software be used? Who is going to use the software?
  • Next, analyze those requirements for feasibility and validity: cost, performance, functionality.
  • Then, evaluate the scope of project and identify available resources.
  • Lastly, consider project opportunities and risks in each software development life cycle phase.

2. UI/UX Design

The second phase of the software development life cycle is where the entire architecture of the future project is created. During the design phase, testers come up with testing strategy like what needs to be tested, and how it needs to be tested.

  • Every required component specifies systems architecture, configurations, data structure.
  • Desired output including prototypes, pseudocode.
  • Design details like the functional logic, interface details, dependency issues, and errors.

For example, in website development, where functionality is limited, design phase involve the creation of a very limited prototype before development begins.

3. Software Development

After all requirements analysis and design choices are already defined, the actual coding starts. In fact, this is the longest phase of the entire software development lifecycle.

But, you should consider how the project moves between different members of your team to avoid any dependencies. (for example, front-end and back-end developers, web and mobile developers)

4. Testing and Quality Assurance

Once the code is fully created, testing is carried against the requirements. The testing phase of SDLC is about quality assurance. Testing also involves the checking of any faulty parts of the code and their fixes.

  • Develop a test plan based on the predefined software requirements.
  • Identify the resources available for testing such as instructions and assignments for testers, selects types of tests and reports to technical executives.
  • Work collectively with development teams to improve test results.

Even if having automated testing systems, nothing beats a good testing session by dedicated QA team. So, get your testing team together, try out the product, log bugs and generally push the code to breaking point. After that, send it back to the developers to fix.

5. Deployment

After the software has been tested, the final deployment takes place. But, this is not as simple as the click of a button. There are a lot of things to consider in this software development life cycle process, including:

  • Who will give the final approval before launch?
  • Do you launch it to everyone in production or selected users?
  • If there are issues with the deployment, what will you do next?

6. Maintenance

In the final phase of the SDLC, it’s important to acknowledge that all software requires maintenance. If users find any issues, the problem can be fixed in the next release.

It can be useful to plan for that, which includes:

  • How often maintenance is required?
  • What the maintenance process looks like?
  • What to do if a product has a bug?

Software Development Life Cycle Models

The product development life cycle models are often chosen depend on multiple factors. It may be: the business requirements or time and budget available for the SDLC process.

But, there are many different ways you can actually approach, organize, and execute development process. Don’t worry!

This article will answer all your questions about models of software development life cycle available. Additionally, you will decide on the one that best fits the project at hand.

Agile software development life cycle

agile software development life cycle agile software development

Up to date, Agile SDLC is one of the most popular software development models. With Agile development, the product is divided into small incremental builds and delivered in iterations. All tasks are divided into small time frames in order to prepare working functionality with each build. The final product build contains all the required features.


  • Provided flexibility to promote the development of software in small, quick steps
  • Release updates to users more frequently based on continuous iterations
  • Highly adaptive to changing requirements
  • Identify minor issues before they can evolve into bigger ones
  • Products get to market faster
  • Better communication between users and product owners


  • Hard to predict what the final product will look like
  • Due to lack of documentations, the process quite challenging
  • High-risk probability when clients unsure about requirements
  • Strict demands in terms of the scope to be done in time

Agile software development life cycle is designed to almost any type of project, but with a lot of engagement from the client. Moreover, if your clients need some functionality to be done fast, Agile software development is priority.

Traditional SDLC vs Agile SDLC

The Agile software development focused on adapting to flexible requirements and satisfying users and clients by delivering working software early. While traditional software development life cycle like Waterfall, V-shaped, Iterative and Spiral models are all belong to the predictive approach.

In the nutshell, all of them are designed to sacrifice the development requirements and expectations. But how to choose the right software development life cycle for your company? What works will deliver the most value to your clients?

Traditional software development life cycle

2. V-shaped SDLC Model

The V-Shaped model is an extension of the Waterfall SDLC approach. With the V-Model, the process is like flowing water, where the development team does not move in a straight line but step by step after testing and coding.

Especially, early testing is typical for V-Model SDLC projects. There, every development stage has a parallel testing phase. And a team moves on to the next only after the previous stage is complete.


  • Easy to use and explain
  • Smooth tracking of potential defects
  • Offer simplicity, clear verification at every stage
  • Fit for small projects with understandable requirements
  • Saves a lot of time as planning and designing related to testing is done way before the actual coding takes place


  • Less flexible than the Waterfall model with no support for iterations
  • No early prototype available during the implementation phase
  • Hard to make adjustments due to no handling of parallel

Just remember that V-Model are the same as in Waterfall. But the V-shaped SDLC model you cannot easily move back a step to fix or add something.

If your software product is new, or you are not sure about the final functions, this model won’t work for you.

3. The Iterative approach

Instead of beginning with complete knowledge of requirements, the team develops a product in cycles, building small parts in an evolutionary way. In this case, team only needs the requirements for the functional part. Subsequently, all requirements can be expanded upon later in the development process.

This model contains the steps from other SDLC models — analysis, design, coding, testing, and back to analysis. Unlike agile, the iterative model requires less customer involvement and has a pre-defined scope of increments. Yet it still shares the same goals as an agile model.


  • Identify functional or design flaws at the earliest stages
  • Each iteration is easy to evaluate
  • Allows more focus on user value
  • Provide space for flexibility like changing needs of the clients as well as the project
  • Lower the delivery cost
  • Make the delivery of the end product speedier


  • As incomplete requirements at the early stages, the design problems may occur
  • Demands added management attention
  • May be hard to integrate resources if they aren’t planned in advance

As the result, the Iterative model works best for projects where major requirements are defined but some functionalities may evolve. Or, products with high-risk features that may need to be changed.

Besides, the process of this model should be used wisely. Otherwise, it may quickly drain the resources for unnecessary changes. The iterative approach is not the best choice for startups with limited financial.

4. Spiral SDLC Model

The Spiral methodology is one of the most flexible SDLC models. The whole development process is divided into a lot of small phases for teams to follow.

Typically, it features the same phases as Waterfall in the same order such as requirements gathering, design, implementation, and testing.


  • Estimate new changes at a later stage of the development
  • If the prototyping is done in small increments, cost estimation becomes easier
  • Higher quality of risk at each phase
  • Faster involvement of the development team and users


  • High risk of management due to not meeting budget or schedule deadlines
  • More money and time required to get the finished product

In response, the Spiral methodology works best for complicated projects with small functionality or strict budgets. It is also suitable for projects with no clear requirements at the early stages, or with requirements that need to be evaluated.

Waterfall vs Agile SDLC

waterfall vs traditional software development life cycle model

In the Waterfall model, tasks and phases are completed one by one in a strict order. You need to finish one phase before moving to another one. Plus, there is no going back. And every stage depends on the previous one.


  • Easy to manage for the team
  • Easy to explain to the clients
  • Plan and schedule with clear milestones
  • Errors are easy to verify at each stage
  • Technical documentation is easy to understand


  • Inflexibility
  • High risk of bugs
  • Compared to Agile model, take more time to make the final delivery
  • Difficult to measure client needs in terms of a functional specification during the requirements phase

To sum up, this SDLC model are easy to manage with stable and clear definition of the product. But the fact that there is almost no room for revisions once a stage is finished. So that, fixing any problems are challenging.

Agile or Waterfall? Which methodology is right for your project?

Bothe software development life cycle models have pros and cons. However, the Waterfall model implies challenges to projects that lack of time and resources for implementation and support.

On the other hand, the Agile SDLC model is known for its flexibility. Changes can be made at any stage of the development process.

Below, you can see a comparison table that explains where it is better to use the Agile SDLC model and what projects would benefit from the traditional SDLC methodology.

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