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In this section, we are going to discuss the difference between the SDLC and STLC as we understood that both are an integral part of Software testing.

But before we see the difference between SDLC and STLC, first, we will understand the SDLC and STLC in brief.

What is SDLC?

Software Development Life Cycle [SDLC] is a classification of individual activities executed throughout the software development process.

The SDLC includes various phases, and each phase has several activities, which help the development team design, create, and deliver a high-quality product.

What is STLC?

Software Testing Life Cycle [STLC] is the order of different activities executed throughout the software testing process. Testing itself has many phases called STLC, and each activity is done to improve the quality of the software product.

Difference between SDLC and STLC

In the below table, we have listed some of the important difference between the Software Development Life Cycle and Software Testing Life Cycle:

S.NO Comparison basis SDLC STLC
1. Explanations It is primarily connected to software development, which means that it is the procedure of developing a software application. It is mainly linked to software testing, which means that it is a software testing process that contains various phases of the testing process.
2. Representation SDLC stands for Software Development Life Cycle. STLC stands for Software Testing Life cycle.
3. Resources While performing the SDLC process, we needed a greater number of developers to complete the development process. The STLC process needed a smaller number of testers to complete the testing process.
4. Focuses on Besides the development phase, other phases like testing are also included. The STLC concentrate only on testing the software.
5. Objective The objective of the Software development life cycle is to complete the development of software successfully. The objective of the Software testing life cycle is to complete the testing of software successfully.
6. Help in The SDLC will help us to develop a good quality software product. The STLC will helps to create the software bug-free.
7. Different phases The various phase includes in Software Development Life Cycle are as follows:
  • Requirements Collection
  • Feasibility Study
  • Design
  • Programming or Coding
  • Testing
  • Installation
  • Maintenance
The various phase includes in Software Testing Life Cycle are as follows:
  • Requirement collection or System study
  • Test Plan
  • Write test case
  • Traceability Matrix
  • Defect Tracking
  • Test Execution Report
  • Retrospect meeting
8. Requirement collection phase In the SDLC Requirement collection phase, the BA [Business Analyst] and PA [ Product Analyst] will collect the requirements and interpret business language into software language. In the Requirement Analysis phase of the STLC, the QA [ Quality Assurance]
team will study requirement documents and prepare the System Test Plan.
9. Designing phase Based on the requirement understanding, the development team will develop the HLD [High-Level Design] and LLD [Low-Level Design] of the software. Generally, in STLC, the Test Architect or a Test Lead plan the test strategy.
And also finds the testing points.
10. Coding phase In the SDLC coding phase, the developer will start writing the code as per the designed document and beginning of building the software. In STLC, the QA team writes the test scenarios to authenticate the quality of the product.
11. Environment Set up After writing the code, the development team sets up a test environment with the developed product to validate the code. Based on the prerequisites, the Test team confirms the environment set up. And do one round of smoke testing to ensure that the environment is stable for the product and ready for testing.
12. Testing Phase Once the environment has been set, the test engineer will perform various types of testing, such as Unit, Integration, System, Retesting, Regression testing, and so on.
And the development team is also involving to fixing the bugs and report back to the tester.
Based on the test cases, the tester will do one round of integration and system testing.
While performing the testing, if they encounter with any bugs, it will be reported and fixed after the retesting.
13. Deployment/ Product Release phase In the SDLC deployment phase, when we received sign-off from various testing teams, the application is deployed or installed in a production environment for real end-users. In STLC, the Smoke and sanity testing are performed in the production environment as soon as the product is deployed.
And the testing team will prepare the test reports and matrix to analyze the product.
14. Maintenance Phase Once the product has been deployed, the development team includes support and release updates. To check maintenance code deployed, the QA team performs the regression suites.
15. Performed The SDLC phases are done before the STLC phases. The STLC phases are completed after SDLC phases.


The SDLC and STLC provide a structure to the development and testing of software.

Generally, the test engineer may feel that the Software development life cycle is appropriate to developers only. Still, after understood the complete process of the development and testing life cycle, we can say that both life cycles are dependent and time to time performed in parallel.

Hence, it is beneficial even to test engineers if they understand the SDLC phase with STLC.

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