Key deliverables for backend development typically include:

1. Project Planning:

1. • A detailed project plan outlining the scope, timeline, and milestones of the backend development project.

2. Requirements Specification:

1. • Clear documentation of functional and non-functional requirements based on stakeholder needs, focusing on server-side aspects.

3. System Architecture:

1. • Design and documentation of the backend system architecture, including servers, databases, and APIs.

4. Database Design:

1. • Design and implementation of a robust database structure to store and retrieve data efficiently.

5. API Development:

1. • Creation of application programming interfaces (APIs) to enable communication between the frontend and backend components.

6. Server-side Scripting:

1. • Implementation of server-side logic using a programming language suitable for backend development (e.g., Node.js, Python, Ruby, Java).

7. Authentication and Authorization:

1. • Implementation of secure user authentication and authorization mechanisms to control access to different parts of the application.

8. Data Validation and Sanitization:

1. • Implementation of measures to validate and sanitize user input to prevent security vulnerabilities such as SQL injection.

9. RESTful Services:

1. • Development of RESTful services to handle requests from the frontend and provide data in a standardized format.

10. Security Features:

1. • Implementation of security measures to protect against common backend vulnerabilities, such as injection attacks and unauthorized access.

11. Error Handling:

1. • Establishment of robust error handling mechanisms to log and handle errors gracefully, providing meaningful feedback to users and developers.

12. Performance Optimization:

1. • Optimization of backend code and database queries to ensure efficient performance, scalability, and responsiveness.

13. Scalability Planning:

1. • Consideration of scalability factors and implementation of strategies to handle increased user loads and data growth.

14. Data Migration and Seeding:

1. • Development of scripts or processes for database migration and seeding initial data for application setup.

15. Caching Strategies:

1. • Implementation of caching mechanisms to improve the speed and responsiveness of data retrieval.

16. Logging and Monitoring:

1. • Implementation of logging and monitoring tools to track the performance and identify issues in the backend system.

17. Version Control:

1. • Utilization of version control systems (e.g., Git) to track and manage changes to the backend codebase.

18. Testing:

1. • Rigorous testing of the backend code, including unit testing, integration testing, and system testing, to identify and fix bugs.

19. Documentation:

1. • Comprehensive documentation that includes API documentation, database schemas, and code documentation for future reference and maintenance.

20. Security Audits:

1. • Periodic security audits and assessments to identify and address potential vulnerabilities in the backend code.

21. Continuous Integration/Continuous Deployment (CI/CD):

1. • Implementation of CI/CD pipelines to automate the process of building, testing, and deploying backend code changes.

22. Training:

1. • Training materials and sessions for administrators and other stakeholders to understand and manage the backend system.

23. Maintenance and Support Plan:

1. • A plan for ongoing maintenance, support, and updates to ensure the continued smooth operation of the backend system.

Coming to an agreement on the abovementioned deliverables based on realistic timelines with adequate resources is in our opinion the best practice approach that contributes to the highest probability of successful development and maintenance of a robust and secure Backend Solutions for the targeted web applications.