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How It Works

Understanding how Inspectr operates helps you get the most out of its features. This page breaks down the high-level flow of how requests are captured, analyzed, and displayed in real time.

Overview

Section titled “Overview”

Inspectr sits between your client (frontend, curl, API tool) and your backend or external service. It captures every request and response, adds visibility, and optionally mocks or exposes the traffic externally.

You can think of it as:

End-to-End Flow

Section titled “End-to-End Flow”

1. Start Inspectr

Section titled “1. Start Inspectr”

You launch Inspectr with CLI flags or a .inspectr.yaml config:

Terminal window
inspectr --listen=:8080 --backend=http://localhost:3000

2. Inspectr Listens

Section titled “2. Inspectr Listens”

Inspectr listens for incoming HTTP requests on the configured port (default :8080).

3. Incoming Request Captured

Section titled “3. Incoming Request Captured”

When a request is received, Inspectr:

  • Parses headers, query params, path, and body
  • Creates an internal operation object to store metadata

4. Routing Decision

Section titled “4. Routing Decision”

Inspectr decides what to do with the request:

  • Forward to backend if --backend is defined
  • Mock a response if --mock-backend is defined
  • Catch it if --catch is true (default when no backend is set)

5. Response Returned

Section titled “5. Response Returned”

Inspectr returns the appropriate response to the client:

  • Backend response
  • Mocked OpenAPI response
  • Default 200 OK (catch mode)

6. Store + Broadcast

Section titled “6. Store + Broadcast”

The request and response are:

  • Stored in-memory or SQLite (for later search/replay)
  • Sent as an SSE (Server-Sent Event) to the Inspectr App

7. UI Display

Section titled “7. UI Display”

In the browser, the Inspectr App (default http://localhost:4004) shows:

  • Live request logs
  • Headers, bodies, status codes
  • Replay options and override flags

Optional Features

Section titled “Optional Features”
  • Ingress Mode: Expose your proxy via in-spectr.dev
  • Response Overrides: Use headers to simulate delays, errors, or switch examples
  • Mock Mode: Use OpenAPI specs to respond even if your backend is unavailable
  • Catch Mode: Catch and view any incoming requests without forwarding

Summary

Section titled “Summary”

Inspectr captures traffic in real time, whether you’re testing integrations, debugging webhooks, or mocking APIs. It gives full visibility into what’s happening between client and backend.