Waterfall vs Agile: What’s the difference?

In pop culture, software development is often presented as an individual venture. The stories behind today’s tech giants take on an almost mythological sheen: One or two coders working nights and weekends in a garage. No funding, no company, just a whole lot of code. 

That’s great when you’re starting out, but at the end of the day it’s not a sustainable model. Eventually, you’ll need a team (or teams)—complete with project managers, owners, and team leads. Whether you like it or not, other stakeholders will have to get involved. 

And as more stakeholders are introduced, you’ll need a way to keep everyone on the same page. In other words, you’ll need a project management strategy. In software development, there are two main project management methods: Agile and waterfall. 

In this post, we’ll break down the differences between Agile and waterfall and the pros and cons of each. Remember, there’s no “right” project management strategy for you and your team—you might use the Agile method for some projects and the waterfall method for others. Keep reading to learn how to pick the right method for each of your projects!

What is Agile methodology?

The Agile methodology is an approach to software development that emphasizes flexibility, efficiency, and the rapid delivery of a product. It’s built on four core values and 12 core principles, which are outlined in the Agile Manifesto. 

Before getting into any more details, let’s clear up a common misconception. People often mistake Agile methodology for a framework, a step-by-step process for developing a product. But the Agile methodology is a philosophy—a way of approaching a project. There are a number of frameworks or methods that fall under the Agile umbrella (Kanban and Scrum, for example).

How Agile methodology works

Though they vary in other ways, Agile frameworks are all built around the sprint—a short, pre-defined period of time for achieving a set of deliverables. (Typically, sprints are two weeks long, but you can change this based on your team’s needs.) 

At the beginning of each sprint, your team will decide on a set of deliverables you’d like to complete. As the project unfolds, your team should be in constant communication with other stakeholders. Based on the conversations you have, you can reprioritize and adjust your deliverables during a sprint. 

In the Agile methodology, coding and testing are not broken into separate phases—both happen during each sprint. The goal is to deliver a working product, not a perfect product. In subsequent sprints, you can improve the software iteratively. 

Because of the short timespan of each sprint—and the constant communication—Agile methodology is incredibly flexible. You’re not committed to a sprawling timeline—you can make changes to on the fly to deliver the best possible product to the customer. 

Benefits of Agile methodology

There are many advantages of Agile methodology, but at the end of the day you’ll have to be the one to decide if it’s for you. To help keep you informed, we’ve broken down three key benefits of Agile methodology for you:

• Collaboration and stakeholder engagement: Throughout each sprint, the development team, client, and other stakeholders discuss the product and deliverables. This frequent communication allows developers to quickly integrate feedback into the product, keeping the client informed and satisfied and resulting in a better finished product. 
• Flexibility and adaptivity: No matter how you approach it, it takes a while to develop a good piece of software. If you’re working linearly, the client’s needs and market demands may change before you finish the product. Because Agile methodology is an iterative approach, you can adjust the software to meet changing demands throughout the development process.
• High quality products: Traditional software development strategies are broken into clear phases: Code first, then test. While this approach has its benefits, you might reach the testing phase only to realize you have a buggy, low-quality product. Agile methodology integrates coding and testing into each sprint, so you know exactly where the product is at—and with each sprint you’re improving it!

Disadvantages of Agile methodology

For all its strengths, Agile methodology also has its weaknesses. (If it didn’t, there wouldn’t be an Agile vs. Waterfall debate!) Here are some disadvantages of Agile methodology to keep in mind: 

• Best suited for mid- to large-scale projects: For a short-term project, a linear approach is often best—it’s straightforward and there’s not much time for the project to derail. To really see the benefits of Agile methodology, a project needs to last several sprints. For small projects, this isn’t always feasible. 
• Requires lots of communication: Agile methodology requires a lot of communication (and this means meetings!) between team members, stakeholders, and the customer. If your team tends to struggle with collaboration or you can’t commit to the time required for this level of communication, Agile might not be the best fit for your team. 
• Higher cost: Because Agile methodology operates in two week sprints, it can often be difficult to create an overall timeline. To handle delays and unforeseen obstacles, you might need to add additional sprints to the project life cycle. This means more time and more money. 

What is waterfall methodology?

If I asked you to describe a traditional software development strategy, you’d probably land on something close to the waterfall methodology. Whereas Agile is an iterative approach, the waterfall method is linear. Development is broken into distinct phases—before moving on to a new phase, you must complete the current one and have your work signed off by a supervisor. 

Though the exact phases defined in the waterfall approach vary from project to project and from team to team, the overall structure typically looks something like this: 

• Phase 1: Conception — What type of software will you be building? This will likely be determined by the client. 
• Phase 2: Analysis — What are the technical requirements of your project? These could be features, functionality, etc. 
• Phase 3: Design — How will you achieve those requirements? 
• Phase 4: Construction — It’s time to get coding! 
• Phase 5: Testing — Once you’ve finished coding, it’s time to see if you were successful. Does the final product meet the requirements?

As you’ve probably gathered, the waterfall method is fairly straightforward and rigid. Each phase has clear guidelines that have to be met before moving on. 

Benefits of waterfall methodology

It’s tempting to view Agile methodology, with its flexibility, as the superior methodology, but that’s not always the case. Remember: Flexibility can also lead to uncertainty. In some situations the rigidity of the waterfall methodology can be just what you need. Let’s take a look at the strengths of the waterfall method: 

• Clear timeline and expectations: Because the waterfall method is a linear approach to software development, it’s much easier to accurately predict the duration and cost of a project before you begin. 
• Leaves room for other projects: Agile software development works best if each team member is fully committed to their project. Sprints are too short to allow team members to work on other projects. With the waterfall approach, team members are often able to split their attention between multiple projects. (This, of course, depends on the scope of said projects.)
• Less customer involvement: This could be a blessing or a curse—it all depends on how your team prefers to work. If your developers are independent, less customer involvement means more room for them to get things done. 

Disadvantages of waterfall methodology

There’s two sides to every methodology. We’ve covered the pros of the waterfall method, now let’s take a look at the cons:

• Less flexibility: In the waterfall approach product requirements and specifications are defined before coding begins. This means that once development starts, it’s hard to implement any changes to those requirements. The train has left the station—any changes will cause delays and headaches. 
• Late feedback: The linear structure of the waterfall method saves feedback for the end—after coding and testing have been completed. If the customer is unhappy, you may have to make substantial changes to your product. And these changes will cost more time and money.
• Not effective for large projects: Imagine working on a multi-month project linearly. You plan and code for months on end, only to reach the testing phase and the product isn’t functional. Or maybe the customer changed their mind and wants you to make substantial changes. Sounds like a disaster right? That’s the risk you take using the waterfall method for large-scale projects.

Key differences between Agile and waterfall

At this point you should have a good sense of the waterfall and Agile methodologies and the pros and cons of each. But let’s take a closer look at some of the key differences and how those differences impact your team:

Project scope 

If your team uses the waterfall approach, the scope of a project will be determined in advance. This takes rigourous planning, but gives you a better sense of the duration of your project, as well as the resources needed to complete it. 

With Agile software development, you should also have some sense of a project’s scope before you begin. Here’s the difference: The scope can change before you complete the project. If a customer decides they want additional features, your team can add sprints to implement those changes. This flexibility can help your team deliver a great product, but it’s difficult to accurately predict the duration, scope, and cost of a project.

Team

The methodology you choose to use determines not only the way you develop a product, but also the way your team operates and interacts with stakeholders. The waterfall method allows your team to take a hands-off approach. The customer is involved primarily at the beginning and end of the project’s life cycle—everything in between is up to your team. Plan meetings with team members as needed, but communication might be relatively sparse. 

Agile, on the other hand, requires full commitment from each team member. There’s no room for developers to be working on multiple projects. Your team should hold Agile meetings daily and update the customer at least once per sprint. 

Feature prioritization 

In the waterfall approach, product features are determined in the analysis phase (before development begins). And all features are prioritized equally: They just need to be finished before the testing phase begins. 

Agile software development allows for more flexibility. If a customer decides they don’t want a feature, no problem—just send it to the bottom of the stack. Similarly, if a new feature is introduced or an existing one is reprioritized, you can address those changes in the next sprint. 

Choosing between Agile and waterfall

For small-scale projects with clearly defined deliverables—anything under a month, give or take a few weeks—the waterfall method can’t go wrong. The customer knows what they want and you know how to give it to them—it should be pretty straightforward. 

It’s those long, unpredictable projects where Agile really shines. If you think there’s a chance requirements may change, save yourself a headache and use Agile. For those sorts of projects, the product owner and customer both should be heavily involved—this involvement is built into the Agile process. 

At the end of the day, it’s all about your organization. If your team is comfortable and successful with the waterfall approach, you don’t necessarily need to change things up. Each method has its strengths and weaknesses—it’s up to you to decide which is best!