How to Delay or Block API Calls to Test App Error States
ProxyCeptor enables developers to delay or block API calls directly in the browser or embedded apps without modifying server code. By setting artificial latency in milliseconds or configuring hard blocks (simulating dropped connections or 4xx/5xx responses), teams can rigorously test UI loading states, Axios/Fetch timeout boundaries, automated retry algorithms, and fallback error screens.
The Core Challenge & Workflow
Modern frontend applications frequently break when third-party microservices experience intermittent latency or sudden connection drops. ProxyCeptor gives frontend developers and QA engineers granular control over network timing and failure simulation without re-deploying code or spinning up complex backend stubs.
Key Capabilities & Features
Millisecond-Granular Latency Injection
Introduce precise network delays (e.g., 2500ms, 5000ms, or 10000ms) on specific URL patterns to test loading skeletons, spinners, and TanStack/Axios timeout limits.
Hard Connection Drop Simulation
Simulate offline status, aborted network connections, and socket timeouts to test how your web or Smart TV app gracefully degrades.
Status Code Error Mocking
Force immediate 400 Bad Request, 401 Unauthorized, 403 Forbidden, 429 Rate Limited, 500 Server Error, and 504 Gateway Timeout responses.
Zero SSL Certificate Requirement
Works across desktop Chrome, Android TV, Samsung Tizen, LG webOS, and Fire TV without installing invasive root CA certificates.
Feature Comparison: ProxyCeptor vs Rivals
| Feature | ProxyCeptor | Requestly | WireMock | Mockoon | Charles |
|---|---|---|---|---|---|
| Millisecond Latency Injection | Yes (Native) | Yes | Yes (Server) | Yes (Local) | Yes (Throttle) |
| Hard Request Blocking | Yes | Yes | Yes | Limited | Yes (Breakpoints) |
| Zero-Cert Smart TV Testing | Yes (In-Memory SDK) | No (Cert required) | No (Server only) | No (Desktop only) | No (Root cert required) |
| Works Without Redeploying | Yes (1-Click) | Yes | No (Server rebuild) | No (Standalone mock) | No (Proxy setup) |
Step-by-Step Implementation Guide
Open ProxyCeptor & Create Rule
Open Chrome DevTools (ProxyCeptor panel) or navigate to the ProxyCeptor Cloud Dashboard.
Specify Matching Endpoint
Enter the target URL pattern (e.g., `https://api.example.com/v1/checkout*`) with wildcard or regex matching.
Configure Delay or Block Action
Select "Add Delay" and enter `3500` ms, or select "Block Request" to simulate an instant network drop.
Trigger & Verify Error State in App
Execute your application flow to confirm that loading skeletons appear, timeout timers fire, and fallback banners render correctly.
Rule Configuration JSON
{ "id": "rule_simulate_checkout_timeout", "name": "Simulate Checkout Gateway Timeout", "pattern": "https://api.example.com/v1/checkout*", "matchType": "wildcard", "action": "delay", "delayMs": 4500, "responseStatus": 504, "responseHeaders": { "x-proxyceptor-injected-delay": "4500ms" }, "enabled": true}Frequently Asked Questions
Try This Solution Live in ProxyCeptor
Intercept, mock, delay, or merge API traffic inside your browser or Smart TV application in less than 60 seconds with zero SSL certificates.