SimpleMock

Local API mocking: return custom responses for Fetch / XHR requests.

SimpleMock lets you return custom API responses while developing and testing web applications. It supports Fetch and XMLHttpRequest (XHR), and mocked responses remain visible in Chrome DevTools → Network → Response. Features: • Create rules with custom response bodies, status codes, and delays. • Match requests by URL, method, website origin, payload, and request headers. • Organize rules into groups. Search, reorder, duplicate, and turn rules on or off. • Import and export rule groups. • Create editable rules from selected real responses in DevTools. • Edit JSON with syntax highlighting and formatting. • Choose light, dark, or browser-based themes. • Available in English, Japanese, Simplified Chinese, and Traditional Chinese. Rules and preferences are stored locally in your browser profile. No account or external server is required, and the extension does not send your rules or captured data to the developer. SimpleMock uses Chrome's debugger API to mock responses. Chrome displays a debugging banner while mocking is active; clicking Cancel stops mocking.