Reversing Network

Reversing Network (Browser → HTTP)

Replace browser automation with faster, more reliable HTTP requests by reverse-engineering the underlying API with robomotion-browser-mcp network capture.

Pairs with: exploring-browser — capture traffic there during exploration, then come here to convert.

When to Use This

Step 1: Capture Network Traffic with Browser MCP

Open a browser with network capture enabled, then perform the target actions:

1. browser_open(stealth: true)
2. browser_start_network_capture(url_filter: "api.", capture_body: true)
3. browser_navigate(url: "https://example.com/search")
4. browser_snapshot()  — read the page to find interactive elements
5. browser_click / browser_type — perform the user action (search, login, etc.)
6. browser_get_requests(method: "POST")  — list captured API calls
7. browser_get_request_response(request_id: "...")  — inspect a specific pair

Use browser_snapshot() between actions to see the page state. Repeat click/type/snapshot until the target API calls appear in browser_get_requests.

Step 2: Analyze the Captured Request

From the JSON returned by browser_get_request_response, inspect:

• Request: request.method, request.url, request.headers, request.body
• Response: response.status, response.headers, response.body, response.mimeType

Identify:

1. Endpoint URL — often contains version (/api/v2/products)
2. Required headers — Authorization, X-API-Key, cookies, Content-Type
3. Request body format — JSON, form-data, GraphQL
4. Authentication flow — does login return a Bearer token?

Step 3: Build the HTTP Flow

import { flow, Message, Custom, Credential } from '@robomotion/sdk';

const myFlow = flow.create('main', 'API Scraper', (f) => {
  f.node('start', 'Core.Trigger.Inject', 'Start', {})

  // Step 1: Authenticate (if needed)
  .then('auth', 'Core.Net.HttpRequest', 'Login', {
    optUrl: Custom('https://api.example.com/auth/login'),
    optMethod: 'post',
    inBody: Custom(JSON.stringify({ username: '...', password: '...' })),
    inCustomHeaders: [{ scope: 'Custom', name: { name: 'Content-Type', value: 'application/json' } }],
    outBody: Message('auth_body'),
    outStatus: Message('auth_status')
  })

  // Step 2: Extract token from response
  .then('token', 'Core.Programming.Function', 'Extract Token', {
    func: `
      msg.bearer_token = 'Bearer ' + msg.auth_body.token;
      return msg;
    `
  })

  // Step 3: Build headers object with token
  .then('headers', 'Core.Programming.Function', 'Build Headers', {
    func: `
      msg.headers = {
        'Authorization': msg.bearer_token,
        'Content-Type': 'application/json',
        'User-Agent': 'Mozilla/5.0'
      };
      return msg;
    `
  })

  // Step 4: Call the actual data API
  .then('api', 'Core.Net.HttpRequest', 'Get Data', {
    optUrl: Custom('https://api.example.com/products?page=1'),
    optMethod: 'get',
    inHeaders: Message('headers'),
    outBody: Message('api_body'),
    outStatus: Message('api_status')
  })

  // Step 5: Parse and process
  .then('parse', 'Core.Programming.Function', 'Parse Response', {
    func: `
      msg.products = msg.api_body.items;
      return msg;
    `
  })

  .then('stop', 'Core.Flow.Stop', 'Done', {});
});

myFlow.start();

Step 4: Handle Pagination

For paginated APIs, use the loop pattern:

// ForEach over page numbers or use cursor/offset from response
f.node('loop', 'Core.Programming.ForEach', 'Each Page', {
  optInput: Message('page_numbers'),  // [1, 2, 3, ...]
  optOutput: Message('page_num')
})
// ... make API call with page_num ...
f.node('goto', 'Core.Flow.GoTo', 'Next', {
  optNodes: { ids: ['LABEL_ID'], type: 'goto', all: false }
})

Key Rules

1. Always verify the API response format before building the full flow
2. Store credentials in vault — never hardcode API keys or tokens
3. Handle rate limits — add delayBefore or retry loops for 429 responses
4. Check token expiry — some tokens expire; add refresh logic if needed
5. Core.Net.HttpRequest is built-in — no extra dependency needed (it's in the Core package)

Common HTTP Node Properties

Verify exact names with robomotion describe node Core.Net.HttpRequest:

Cleanup

Always call browser_stop_network_capture and browser_close when done capturing, even if the flow build fails. Leaving the browser open wastes resources and can block subsequent runs.