API-Mate

Inspiration

Frontend developers often have to wait for backend APIs to be completed before they can properly build and test their applications. We wanted to remove that dependency. ApiMate was inspired by the idea that developers should be able to define their API contract, start working with realistic data immediately, and connect to the real backend later without rewriting their frontend.

What it does

ApiMate turns API schemas into live, realistic mock APIs in seconds. Developers can define schemas manually or generate them using AI, publish versioned API contracts, and immediately use live HTTP endpoints for frontend development and testing.

It also provides realistic fake data, request validation, breaking-change detection, version history, and client-code generation for Dart and Java.

How we built it

We built ApiMate as a modern full-stack application using Next.js 16, React 19, and TypeScript for the frontend, with Convex handling the backend and database. Clerk provides authentication, while Google Gemini powers AI-assisted schema generation and validation. AJV is used for JSON Schema validation, with Tailwind CSS for the interface.

The core workflow is:

Define Schema → Publish Version → Generate Live Mock API → Build Frontend → Swap to Real Backend

Published schemas are served through dynamic mock API routes that support GET requests for realistic responses and POST requests for payload validation.

Challenges we ran into

One of the main challenges was designing a system where API contracts, versions, validation, realistic mock data, and live endpoints all work together seamlessly.

We also had to account for breaking changes between API versions and ensure that published schemas remain immutable and reproducible. Another challenge was supporting fully dynamic API routes and ensuring that the application can be deployed on platforms that support the required server-side behavior.

Accomplishments that we're proud of

We are proud to have built a complete workflow that allows developers to start frontend development without waiting for a backend.

Some key accomplishments include:

• Live mock API endpoints generated from schemas
• AI-powered API schema generation
• Realistic, meaningful mock data instead of placeholder values
• Automatic breaking-change detection
• Request validation with AI-assisted fixes
• API contract versioning and restoration
• Dart and Java model-code generation
• Authentication and private project isolation
• A workflow that allows developers to switch to the real backend later with minimal changes

What we learned

Building ApiMate taught us how important API contracts are in modern application development. We learned how schema-driven development can allow frontend and backend work to progress independently.

We also gained experience integrating AI into a developer tool in a practical way—not to replace deterministic validation, but to assist developers with schema generation, realistic data enhancement, and actionable feedback. The project also strengthened our understanding of API versioning, validation, dynamic routing, authentication, and full-stack architecture.

What's next for API-Mate

Our next goal is to make ApiMate a more complete API development and collaboration platform.

The planned roadmap includes:

• Team collaboration with role-based access
• OpenAPI specification import
• Configurable response-delay simulation
• Request logging and debugging
• Webhook simulation
• GraphQL support
• Auto-generated SDKs for TypeScript, Python, and Go
• Contract testing against real backends

Ultimately, we want ApiMate to become the bridge between API design and implementation—allowing teams to design, test, develop, and integrate APIs without blocking each other.

Built With

• ai
• ajv
• api-development
• api-testing
• api-versioning
• automation
• backend-development
• clerk
• code
• convex
• developer-tools
• frontend-development
• full-stack
• generative-ai
• google-gemini
• json-schema
• mock-api
• next.js
• react
• rest-api
• saas
• schema-validation
• tailwind-css
• typescript
• web-development