Requestly is a local-first, open-source tool that merges the functionality of API clients like Postman and HTTP interceptors like Charles Proxy into a single, lightweight platform. Designed for developers who want to test, modify, and mock APIs without cloud login or bloat, it runs as a Chrome/Firefox extension or a desktop app (Electron-based) and stores all data locally by default. It supports Git-native workflows, environment variables, and real-time HTTP request/response manipulation across web, mobile, and desktop apps.
Built with TypeScript and modular architecture, Requestly integrates with existing developer tools via 1-click imports from Postman, Insomnia, Charles Proxy, and ModHeader. Its ecosystem includes a desktop app, browser extension, mock server, and web SDK — all open-source and designed for collaboration through local workspaces, Git sync, and team sharing without mandatory cloud storage.
What You Get
- Local Workspaces - Store all API collections, environments, and mocks as local files on disk; no cloud dependency. Edit directly in VSCode and sync via Git, Google Drive, or iCloud.
- REST API Client - Full-featured API playground with collections, environment switcher, request history, and a clean UI — a Postman/Insomnia alternative with no login required.
- HTTP Interceptor (Rules) - Intercept, monitor, and modify HTTP/HTTPS requests and responses in real time using Chrome/Firefox/Edge extensions or desktop app. Modify headers, URLs, query params, and body content.
- API Mocking - Create static and dynamic API mocks using JavaScript to override server responses. Supports GraphQL queries by operationName, bulk mocking from recorded sessions, and cloud-based mock endpoints.
- 1-Click Imports - Import Postman collections, environments, and scripts; Charles Proxy sessions; ModHeader rules; and Resource Override configurations with one click — no manual re-creation.
- Environment Variables - Define global and collection-level variables to manage different environments (dev, staging, prod) and dynamically inject values into requests and headers.
- Pre & Post Scripts - Write JavaScript to modify requests before sending (pre-request) or process responses after receiving (post-response) for dynamic testing and data transformation.
- Git Sync - Link API collections directly to Git repositories to version control, collaborate, and maintain audit trails using standard Git workflows.
- Multi-Workspace View - Open and manage multiple local workspaces simultaneously to work on different projects without switching contexts.
- Role-Based Access Control - Assign Admin, Editor, or Viewer roles to team members in shared workspaces for secure collaboration in enterprise environments.
- SOC-II Compliance & Enterprise Security - Includes data encryption in transit and at rest, SSO integration, audit logs, and regular security updates for enterprise-grade security.
- Logs History - Maintain a local, searchable log of all API calls made during development for quick reference and debugging.
Common Use Cases
- Debugging API issues in staging - A frontend developer uses Requestly’s HTTP Interceptor to modify API responses from staging to simulate error states or slow responses without touching backend code.
- Building frontend without a backend - A mobile app developer creates dynamic GraphQL mocks using Requestly to simulate API responses while waiting for backend endpoints to be ready.
- Migrating from Postman to a local-first tool - A DevOps team imports their entire Postman collection and environments into Requestly to eliminate cloud dependency and enable Git-based version control.
- Testing API integrations in CI/CD - A QA engineer uses Requestly’s mock server in a Cypress test suite to intercept and mock third-party API calls during automated end-to-end testing.
- Managing multiple environments for a SaaS product - A full-stack team uses Requestly’s environment variables and local workspaces to switch between dev, staging, and prod configurations without manual config changes.
- Collaborating on API specs with Git - A remote team stores their API collections in a private Git repo, uses Requestly’s Git Sync to pull changes, and collaborates using branch-based workflows like they do with code.
Under The Hood
Architecture
- Modular design with clear separation between core rule-processing logic and UI layers, enabling independent development and testing
- Redux-based state management with typed slices and selectors ensuring predictable, unidirectional data flow
- Firebase callable functions decouple frontend UI from backend operations, enhancing security and maintainability
- Component-driven UI built with reusable design system elements and atomic hooks for consistent state logic
- Build pipeline supports ESM/CJS dual exports via Rollup with TypeScript, catering to both browser and Node environments
- Domain-specific configuration files use structured constants and interfaces to eliminate magic strings and enforce type safety
Tech Stack
- React 18 and TypeScript form the foundation of the frontend, complemented by react-redux and react-router-dom for state and routing
- Rollup with Babel and Node-resolve plugins enables production-grade bundling, with terser for minification and dual-module exports
- Firebase provides authentication, hosting, and backend functions, tightly integrated with deployment workflows
- ESLint and Prettier, enforced via Husky and lint-staged, maintain consistent code style across the codebase
- SCSS and Ant Design drive styling, with @react-icons for visual elements and Chrome Extension APIs powering the browser extension
- A dedicated API layer enables communication between the browser extension and the companion web application
Code Quality
- Comprehensive test suite using Playwright and Jest, with clear separation of unit, integration, and end-to-end scenarios
- Strong TypeScript typing extends to test data structures, ensuring reliability and reducing runtime errors
- Consistent naming conventions and modular test organization by rule type improve readability and maintainability
- Robust assertion-based validation in tests ensures correctness, though custom error classes are not utilized
- Code is well-structured with logical separation between UI, rule engines, and test utilities, supporting scalable growth
- Extensive linting and test automation are evident, though configuration files lack explicit documentation
What Makes It Unique
- Native GraphQL schema introspection integrated with CodeMirror 6 enables real-time, type-aware autocompletion without external tools
- Unified desktop and browser extension architecture uses IPC to synchronize rule execution across platforms without cloud dependency
- Dynamic authentication with time-limited localStorage tokens and automatic session invalidation enhances security in desktop environments
- Custom CodeMirror extensions with dark theme optimizations and API-specific tooltips are tailored for testing workflows, not general coding
- Embedded API client with visual validation for CSV/JSON data provides real-time error visualization, reducing debugging friction
- Seamless Stripe subscription flow embedded in the UI, backed by Firebase cloud functions, creates a frictionless in-app upgrade experience