Mock API vs Local Server: Which Should You Use?

DevWallah ships two tools for simulating backend services: Mock API and Local Server. They look similar on the surface, but they serve different use cases. Choosing the right one will save you significant time. Here's the definitive breakdown.

Mock API: Quick, Simple, Shareable

Mock API is designed for speed. You define one or more endpoints, specify a status code and a JSON body, and the service worker routes matching requests to your definitions. There's no persistent state, no database, and no configuration ceremony. It's ready in under a minute.

Best For

• 01Component-level UI development where you need a single endpoint stubbed out
• 02Sharing a demo with colleagues who need a stable, predictable mock
• 03Testing UI states (loading, empty, error) for a specific endpoint
• 04Onboarding new team members to an API contract

Local Server: Stateful, Relational, Powerful

Local Server is a full mock backend. It supports multiple routes, an in-memory database with real SQL, dynamic route parameters, scenario switching, and a live request log. State mutates across requests — a POST that creates a user will make the user visible in a subsequent GET.

Best For

• 01Full feature development where multiple endpoints interact
• 02Testing CRUD flows end-to-end without a real backend
• 03Prototyping a new product when the backend doesn't exist yet
• 04Integration testing across multiple UI components
• 05Generating realistic datasets via SQL joins and schema-based seeding

Side-by-Side Comparison

• 01Setup time: Mock API < 1 min | Local Server 3–5 min
• 02Persistent state: Mock API ✗ | Local Server ✓
• 03Database / SQL: Mock API ✗ | Local Server ✓
• 04Path parameters: Mock API ✓ | Local Server ✓
• 05Scenario switching: Mock API ✗ | Local Server ✓
• 06Request logs: Mock API ✗ | Local Server ✓ (real-time)
• 07Import / Export: Mock API ✓ | Local Server ✓

The Golden Rule

Combining Both Tools

Many teams use both simultaneously: Local Server manages complex authenticated endpoints with persistent state, while Mock API handles static reference data endpoints (like /countries or /config) that never change. Service workers from both tools co-exist without conflict because they are scoped independently.