APIFlow Studio — Free Browser API Testing Platform
APIFlow Studio is an ultra-fast, client-side API testing studio, contract simulator, and synthetic data engine designed for high-velocity software engineering teams. Simulate complex HTTP status codes, export OpenAPI 3.1 and Postman collections, and run live proxy requests directly inside your browser with zero installation.
Zero-Configuration REST API Client & Live Testing
Execute live HTTP requests to any external endpoint, microservice, or webhook without browser CORS restrictions. Using our secure local proxy relay, APIFlow handles headers, query parameters, multipart payloads, and authentication methods seamlessly. Developers can test endpoints securely without worrying about third-party cloud data leaks or CORS preflight failures.
Client-Side Synthetic Mocking & Dynamic Faker Engine
Generate realistic mock responses on the fly without running an external server or registering for third-party mock services. Leverage built-in Faker heuristics to produce synthetic user profiles, dates, UUIDs, ecommerce transactions, and relational mock schemas in milliseconds. Build frontend features against realistic API contracts before backend engineers even finish building endpoints.
Visual Schema Assertions & Quality Verification
Build enterprise-grade API test suites using our no-code visual assertion engine. Verify HTTP status codes, measure response latency against strict SLAs, assert deep JSON paths, and validate response headers to ensure production stability before deployment. Receive instant pass/fail scorecards and automated regression summaries without having to write tedious testing scripts.
OpenAPI 3.1 & Postman Collection Interoperability
Easily import and export existing API collections. APIFlow Studio provides seamless two-way portability with OpenAPI 3.0, OpenAPI 3.1, Swagger, Postman Collection v2.1, and raw cURL commands, guaranteeing zero vendor lock-in for your development team. Move your entire existing workspace over in a single click and share mock scenarios with your teammates instantly.
Local-First Data Sovereignty & Offline Desktop PWA
Keep your API keys, confidential payload drafts, and test history private. APIFlow stores all data on your local device using high-performance IndexedDB storage. Install it as a lightweight Progressive Web App (PWA) on macOS, Windows, and Linux for instant offline developer workflows with zero background memory bloat.