SDLC guides teams to plan, build, test, and deliver software. Discover phases, KPIs, tools, and checklist with our quick start guide.
Picture this: You and your team have spent a tremendous amount of time, money, and effort to develop a piece of software, only to have the client say, “It is not what we need.”
Imagine the frustration and disappointment! You can avoid scenarios like this by applying the software development life cycle (SDLC) to your project.
SDLC is a structured framework that guides the entire software development process. Adopting this framework helps teams deliver high-quality software that meets client requirements — on time and within budget.
During the planning phase, the team determines the project’s scope and requirements — all of which must align with stakeholders’ or clients’ expectations. At the end of this phase, the team should have a plan that details the project’s objectives, goals, timeline, budget, and resources.
Key deliverables/objectives: Project plan, clearly defined goals, resource requirements, budget estimate, and schedule estimate
Read more: Project Plan Examples: How to Write an Effective Plan
This phase focuses on defining and analyzing the software requirements.
These requirements may originate from users, clients, market research, or other stakeholders. The team compiles them into a document known as the software requirements specification (SRS), which serves as the primary reference for software specifications throughout the life cycle.
Key deliverables/objectives: Software requirements specification document
Read more: Best Requirements Management Tools and Software
Based on the requirements outlined in the SRS, the software designers develop the system’s overall architecture.
They may propose several options, all detailed in the software design document (SDD). The SDD is then reviewed by the project team and stakeholders, and the most suitable design is selected for further development.
Key deliverables/objectives: Software design document and design selection
Hands-on development, building, and coding occur in this phase.
Programmers and developers create the software according to the design chosen in the previous phase. They use various programming languages and tools to develop the software through to completion.
Key deliverables/objectives: A working piece of software
During the testing phase, the software developed in the previous stage undergoes a thorough evaluation to ensure it functions correctly and meets user requirements.
This step typically begins by defining test parameters in accordance with the software requirements. The team conducts a series of rigorous tests, including unit testing, integration testing, security testing, system testing, and acceptance testing, to detect any bugs or glitches.
When all parameters are satisfied, the testing phase is considered complete. All activities and outcomes during this stage must be properly documented.
Key deliverables/objectives: Thorough testing records and a final product that satisfies all requirements
Read more: How to improve your application testing system
Once fully tested, the software is shipped to end users, marking the transition from the project phase to the production phase.
Note that it is still the project team’s responsibility to ensure users can operate the software with ease; this may involve providing training, simulations, and user manuals to support a smooth adoption process.
Key deliverables/objectives: A finished product deployed to all end users
The software development life cycle does not end with delivery. A finished product also requires proper maintenance and, potentially, continuous improvement — this is the focus of the seventh phase.
The maintenance stage involves adapting to an ever-changing environment by responding to user feedback, resolving new bugs, and updating the software to meet evolving requirements. Customer support also plays a vital role, providing users with guidance and assistance to earn their trust and foster long-term loyalty.
Finally, a long-term vision for the software needs to be established. This may involve releasing newer versions or even developing an entirely new product.
Key deliverables/objectives: A maintenance plan to ensure the product’s long-term viability
These are several key points to measure success in SDLC:
One of the most crucial aspects in software development is meeting the requirements set by stakeholders (including end users, clients, project sponsors, etc.). The software and user interface should align with their needs and expectations.
Proper SDLC implementation ensures that the goals of all key parties are identified and documented early in the project. This helps prevent misunderstandings or conflicts at the conclusion, when resources, time, and effort have already been invested.
Read more: Understanding Different Types of Stakeholders and Their Roles
A successful project not only satisfies user requirements but also delivers the product within the agreed timeline and the budget set during the planning phase. A project may not be considered successful if it runs over budget or is completed too late.
The software development life cycle helps keep the project on schedule and within budget by clearly defining the scope, requirements, design, and testing, minimizing the possibility of rework.
Read more: How to Deal with Project Cost Overruns (+ Prevention Tips)
A high-quality product should perform as intended, be easy to use, contain minimal or no errors, and have proper security measures in place. While every phase of the SDLC contributes to delivering a valuable end result, the testing phase plays a crucial role by evaluating key quality parameters.
Read more: How to Plan Quality Management in Projects
Considered a crucial part of the software development life cycle, benchmarking, or benchmark testing, involves comparing performance test results against performance metrics. The goal is to measure actual performance and determine whether any changes are needed.
A globally recognized benchmarking method is based on ISO/IEC 19761:2011, which defines software project performance using the COSMIC Software Sizing Standard. It measures productivity based on COSMIC Function Point (CFP).
Several measurements in this benchmarking are:
Read more: 5 tips for measuring developer productivity
There are six common models used in SDLC: Waterfall, Agile, Iterative, V-Model, DevOps, and Spiral.
The following table contains a description of each model, its pros and cons, and the best use case.
| Model Name | Description | Pros | Cons | Best use |
|---|---|---|---|---|
| Waterfall | A classic model that emphasizes completing one phase before moving to another. In Waterfall, each phase cannot overlap. |
|
| Large project with predictable requirements and outcome |
| Agile | The project is divided into smaller incremental parts. Each part is developed in iterations within a two- to four-week sprint. Requirements are reviewed in every sprint. |
|
| Large and complex project with rapidly changing requirements |
| Iterative | The team works on each phase until completion, and the end product undergoes reviews. If there are any changes in the requirements, the team repeats the process from the beginning until they achieve a satisfactory final product. |
|
| Small and complex project with poorly defined scope and unclear requirements |
| V-Model | Also called Verification and Validation, the V-Model is similar to the Waterfall approach, except there is a verification and testing step before moving to the next phase. |
|
| Large and complex project with poorly defined scope and unclear requirements |
| DevOps | DevOps combines development (Dev) and operations (Ops) so that the operation is able to start while the project is still ongoing. |
|
| Large and complex project with modular requirements |
| Spiral | This model combines elements of Iterative and Waterfall. The project team develops the product from the initial phase through to market delivery. After release, the product undergoes further review before being updated and released as a newer version. |
|
| Small and complex project with rapidly changing requirements |
Learn more:
Security and compliance are crucial in a software development project. Those two aspects must be considered throughout all phases, from initiation through completion.
The secure software development life cycle (SSDLC) ensures that products of software development projects are built with security as the top priority. Here are the key principles of SSDLC:
Besides security, software development projects must also adhere to industry-specific regulations and standards. Several important aspects that require compliance are:
Technical debt is the long-term consequences of short-term compromises and shortcuts made while completing a software development project. It is a quick fix that temporarily pushes progress forward, but more often than not, it creates more problems later in the project.
Technical debt is hard to spot, but there are some warning signs:
As shown in Table 1, the right SDLC model for your project depends on several factors, including complexity, size, and potential for requirement changes. In addition, some models are more commonly suitable for certain industries.
For example, agile may suit startups better, as they need to release products to the market quickly with limited budgets. Industries with rigid regulations, such as healthcare or fintech, may find the Waterfall or V-model more suitable.
DevSecOps is an evolution of DevOps that incorporates security from the beginning. In DevOps, security often only comes to mind in later stages. In DevSecOps, security is embedded from the initial phase throughout the process.
The duration of a complete SDLC varies significantly. Its length depends on many factors, including project size, complexity, requirements, and team experience.
On average, a single SDLC takes around 4–9 months. A simple software project, such as a minimum viable product (MVP), may be completed in as little as 4 weeks, while a complex project may take up to 12 months.
