MERN Stack Developer Job Description Template

API design and integration · 20%
Backend API quality and correct integration with the frontend are central to this role’s day-to-day impact. Evaluated in Round 1.

• Weak: Explains endpoints without clear request/response contracts, status codes, and error shapes; struggles to describe how the frontend consumes the API.
• Meets the bar: Describes pragmatic REST endpoint design with consistent error handling and versioning approach; can explain typical integration patterns with React.
• Strong: Designs clear contracts (schemas, status codes, error responses), handles edge cases, and describes how to evolve APIs safely while keeping frontend integration robust.

React feature delivery · 18%
The role requires building maintainable UI components and delivering correct user experiences. Evaluated in Round 1.

• Weak: Describes UI implementation at a high level; has difficulty explaining state management, component boundaries, or data fetching lifecycles.
• Meets the bar: Explains component structure, state/data flow, and how UI reacts to API responses and loading/error states.
• Strong: Delivers well-structured React features with thoughtful state management, performance considerations, and resilient UI behavior for edge cases.

MongoDB modeling and queries · 15%
Correct data modeling and performant queries are essential for stable application behavior. Evaluated in Round 2.

• Weak: Generalizes about databases; struggles to discuss indexing, query efficiency, or schema tradeoffs.
• Meets the bar: Explains how document structure maps to application needs and describes common query patterns and indexing considerations.
• Strong: Designs data models that support required access patterns, explains index strategy, and can reason about query performance and data consistency tradeoffs.

Authentication and security · 15%
Secure auth flows and safe API usage are required for customer/internal web apps. Evaluated in Round 2.

• Weak: Cannot clearly describe how auth works end-to-end or how tokens/sessions are validated and protected.
• Meets the bar: Explains standard auth concepts (e.g., JWT/session), how frontend sends credentials, and how backend authorizes requests.
• Strong: Describes secure end-to-end implementation details (token storage approach, authorization checks per route, handling expired tokens, and mitigating common pitfalls).

JavaScript code quality · 12%
Maintainable JavaScript/ES6+ practices drive long-term velocity and reduce defects. Evaluated in Round 3.

• Weak: Describes code in terms of features only; limited discussion of structure, abstractions, or debugging approach.
• Meets the bar: Cites practical practices: modularization, clear naming, async/await correctness, and readable error handling.
• Strong: Demonstrates strong engineering judgment: clear module boundaries, predictable async flows, defensive coding, and pragmatic refactoring habits.

Independent execution · 12%
Mid-level scope requires independence on well-defined work with effective planning and delivery. Evaluated in Round 3.

• Weak: Relies heavily on others for decisions; cannot describe how they plan work or verify completion.
• Meets the bar: Describes how they break down work, manage tradeoffs, and validate outcomes against requirements.
• Strong: Shows consistent independence: scopes tasks, identifies risks early, communicates progress/decisions clearly, and drives work to completion with measurable results.

Debugging and reliability mindset · 8%
Production troubleshooting and root-cause thinking protect reliability and user trust. Evaluated in Round 3.

• Weak: Focuses on symptoms only; cannot explain how they isolate root causes or prevent repeats.
• Meets the bar: Describes a structured debugging approach and how they verify fixes; mentions basic prevention (logging/tests).
• Strong: Uses evidence-driven debugging (logs/metrics/reproduction), communicates findings, and implements targeted prevention to avoid recurrence.