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+# HTTP API Integration Pattern
+
+**Use Case**: Fetch data from REST APIs, transform it, and use it in workflows.
+
+---
+
+## Pattern Structure
+
+```
+Trigger → HTTP Request → [Transform] → [Action] → [Error Handler]
+```
+
+**Key Characteristic**: External data fetching with error handling
+
+---
+
+## Core Components
+
+### 1. Trigger
+**Options**:
+- **Schedule** - Periodic fetching (most common)
+- **Webhook** - Triggered by external event
+- **Manual** - On-demand execution
+
+### 2. HTTP Request Node
+**Purpose**: Call external REST APIs
+
+**Configuration**:
+```javascript
+{
+  method: "GET",                    // GET, POST, PUT, DELETE, PATCH
+  url: "https://api.example.com/users",
+  authentication: "predefinedCredentialType",
+  sendQuery: true,
+  queryParameters: {
+    "page": "={{$json.page}}",
+    "limit": "100"
+  },
+  sendHeaders: true,
+  headerParameters: {
+    "Accept": "application/json",
+    "X-API-Version": "v1"
+  }
+}
+```
+
+### 3. Response Processing
+**Purpose**: Extract and transform API response data
+
+**Typical flow**:
+```
+HTTP Request → Code (parse) → Set (map fields) → Action
+```
+
+### 4. Action
+**Common actions**:
+- Store in database
+- Send to another API
+- Create notifications
+- Update spreadsheet
+
+### 5. Error Handler
+**Purpose**: Handle API failures gracefully
+
+**Error Trigger Workflow**:
+```
+Error Trigger → Log Error → Notify Admin → Retry Logic (optional)
+```
+
+---
+
+## Common Use Cases
+
+### 1. Data Fetching & Storage
+**Flow**: Schedule → HTTP Request → Transform → Database
+
+**Example** (Fetch GitHub issues):
+```
+1. Schedule (every hour)
+2. HTTP Request
+   - Method: GET
+   - URL: https://api.github.com/repos/owner/repo/issues
+   - Auth: Bearer Token
+   - Query: state=open
+3. Code (filter by labels)
+4. Set (map to database schema)
+5. Postgres (upsert issues)
+```
+
+**Response Handling**:
+```javascript
+// Code node - filter issues
+const issues = $input.all();
+return issues
+  .filter(item => item.json.labels.some(l => l.name === 'bug'))
+  .map(item => ({
+    json: {
+      id: item.json.id,
+      title: item.json.title,
+      created_at: item.json.created_at
+    }
+  }));
+```
+
+### 2. API to API Integration
+**Flow**: Trigger → Fetch from API A → Transform → Send to API B
+
+**Example** (Jira to Slack):
+```
+1. Schedule (every 15 minutes)
+2. HTTP Request (GET Jira tickets updated today)
+3. IF (check if tickets exist)
+4. Set (format for Slack)
+5. HTTP Request (POST to Slack webhook)
+```
+
+### 3. Data Enrichment
+**Flow**: Trigger → Fetch base data → Call enrichment API → Combine → Store
+
+**Example** (Enrich contacts with company data):
+```
+1. Postgres (SELECT new contacts)
+2. Code (extract company domains)
+3. HTTP Request (call Clearbit API for each domain)
+4. Set (combine contact + company data)
+5. Postgres (UPDATE contacts with enrichment)
+```
+
+### 4. Monitoring & Alerting
+**Flow**: Schedule → Check API health → IF unhealthy → Alert
+
+**Example** (API health check):
+```
+1. Schedule (every 5 minutes)
+2. HTTP Request (GET /health endpoint)
+3. IF (status !== 200 OR response time > 2000ms)
+4. Slack (alert #ops-team)
+5. PagerDuty (create incident)
+```
+
+### 5. Batch Processing
+**Flow**: Trigger → Fetch large dataset → Split in Batches → Process → Loop
+
+**Example** (Process all users):
+```
+1. Manual Trigger
+2. HTTP Request (GET /api/users?limit=1000)
+3. Split In Batches (100 items per batch)
+4. HTTP Request (POST /api/process for each batch)
+5. Wait (2 seconds between batches - rate limiting)
+6. Loop (back to step 4 until all processed)
+```
+
+---
+
+## Authentication Methods
+
+### 1. None (Public APIs)
+```javascript
+{
+  authentication: "none"
+}
+```
+
+### 2. Bearer Token (Most Common)
+**Setup**: Create credential
+```javascript
+{
+  authentication: "predefinedCredentialType",
+  nodeCredentialType: "httpHeaderAuth",
+  headerAuth: {
+    name: "Authorization",
+    value: "Bearer YOUR_TOKEN"
+  }
+}
+```
+
+**Access in workflow**:
+```javascript
+{
+  authentication: "predefinedCredentialType",
+  nodeCredentialType: "httpHeaderAuth"
+}
+```
+
+### 3. API Key (Header or Query)
+**Header auth**:
+```javascript
+{
+  sendHeaders: true,
+  headerParameters: {
+    "X-API-Key": "={{$credentials.apiKey}}"
+  }
+}
+```
+
+**Query auth**:
+```javascript
+{
+  sendQuery: true,
+  queryParameters: {
+    "api_key": "={{$credentials.apiKey}}"
+  }
+}
+```
+
+### 4. Basic Auth
+**Setup**: Create "Basic Auth" credential
+```javascript
+{
+  authentication: "predefinedCredentialType",
+  nodeCredentialType: "httpBasicAuth"
+}
+```
+
+### 5. OAuth2
+**Setup**: Create OAuth2 credential with:
+- Authorization URL
+- Token URL
+- Client ID
+- Client Secret
+- Scopes
+
+```javascript
+{
+  authentication: "predefinedCredentialType",
+  nodeCredentialType: "oAuth2Api"
+}
+```
+
+---
+
+## Handling API Responses
+
+### Success Response (200-299)
+**Default**: Data flows to next node
+
+**Access response**:
+```javascript
+// Entire response
+{{$json}}
+
+// Specific fields
+{{$json.data.id}}
+{{$json.results[0].name}}
+```
+
+### Pagination
+
+#### Pattern 1: Offset-based
+```
+1. Set (initialize: page=1, has_more=true)
+2. HTTP Request (GET /api/items?page={{$json.page}})
+3. Code (check if more pages)
+4. IF (has_more === true)
+   └→ Set (increment page) → Loop to step 2
+```
+
+**Code node** (check pagination):
+```javascript
+const items = $input.first().json;
+const currentPage = $json.page || 1;
+
+return [{
+  json: {
+    items: items.results,
+    page: currentPage + 1,
+    has_more: items.next !== null
+  }
+}];
+```
+
+#### Pattern 2: Cursor-based
+```
+1. HTTP Request (GET /api/items)
+2. Code (extract next_cursor)
+3. IF (next_cursor exists)
+   └→ Set (cursor={{$json.next_cursor}}) → Loop to step 1
+```
+
+#### Pattern 3: Link Header
+```javascript
+// Code node - parse Link header
+const linkHeader = $input.first().json.headers['link'];
+const hasNext = linkHeader && linkHeader.includes('rel="next"');
+
+return [{
+  json: {
+    items: $input.first().json.body,
+    has_next: hasNext,
+    next_url: hasNext ? parseNextUrl(linkHeader) : null
+  }
+}];
+```
+
+### Error Responses (400-599)
+
+**Configure HTTP Request**:
+```javascript
+{
+  continueOnFail: true,  // Don't stop workflow on error
+  ignoreResponseCode: true  // Get response even on error
+}
+```
+
+**Handle errors**:
+```
+HTTP Request (continueOnFail: true)
+  → IF (check error)
+    ├─ [Success Path]
+    └─ [Error Path] → Log → Retry or Alert
+```
+
+**IF condition**:
+```javascript
+{{$json.error}} is empty
+// OR
+{{$json.statusCode}} < 400
+```
+
+---
+
+## Rate Limiting
+
+### Pattern 1: Wait Between Requests
+```
+Split In Batches (1 item per batch)
+  → HTTP Request
+  → Wait (1 second)
+  → Loop
+```
+
+### Pattern 2: Exponential Backoff
+```javascript
+// Code node
+const maxRetries = 3;
+let retryCount = $json.retryCount || 0;
+
+if ($json.error && retryCount < maxRetries) {
+  const delay = Math.pow(2, retryCount) * 1000; // 1s, 2s, 4s
+
+  return [{
+    json: {
+      ...$json,
+      retryCount: retryCount + 1,
+      waitTime: delay
+    }
+  }];
+}
+```
+
+### Pattern 3: Respect Rate Limit Headers
+```javascript
+// Code node - check rate limit
+const headers = $input.first().json.headers;
+const remaining = parseInt(headers['x-ratelimit-remaining'] || '999');
+const resetTime = parseInt(headers['x-ratelimit-reset'] || '0');
+
+if (remaining < 10) {
+  const now = Math.floor(Date.now() / 1000);
+  const waitSeconds = resetTime - now;
+
+  return [{
+    json: {
+      shouldWait: true,
+      waitSeconds: Math.max(waitSeconds, 0)
+    }
+  }];
+}
+
+return [{ json: { shouldWait: false } }];
+```
+
+---
+
+## Request Configuration
+
+### GET Request
+```javascript
+{
+  method: "GET",
+  url: "https://api.example.com/users",
+  sendQuery: true,
+  queryParameters: {
+    "page": "1",
+    "limit": "100",
+    "filter": "active"
+  }
+}
+```
+
+### POST Request (JSON Body)
+```javascript
+{
+  method: "POST",
+  url: "https://api.example.com/users",
+  sendBody: true,
+  bodyParametersJson: JSON.stringify({
+    name: "={{$json.name}}",
+    email: "={{$json.email}}",
+    role: "user"
+  })
+}
+```
+
+### POST Request (Form Data)
+```javascript
+{
+  method: "POST",
+  url: "https://api.example.com/upload",
+  sendBody: true,
+  bodyParametersUi: {
+    parameter: [
+      { name: "file", value: "={{$json.fileData}}" },
+      { name: "filename", value: "={{$json.filename}}" }
+    ]
+  },
+  sendHeaders: true,
+  headerParameters: {
+    "Content-Type": "multipart/form-data"
+  }
+}
+```
+
+### PUT/PATCH Request (Update)
+```javascript
+{
+  method: "PATCH",
+  url: "https://api.example.com/users/={{$json.userId}}",
+  sendBody: true,
+  bodyParametersJson: JSON.stringify({
+    status: "active",
+    last_updated: "={{$now}}"
+  })
+}
+```
+
+### DELETE Request
+```javascript
+{
+  method: "DELETE",
+  url: "https://api.example.com/users/={{$json.userId}}"
+}
+```
+
+---
+
+## Error Handling Patterns
+
+### Pattern 1: Retry on Failure
+```
+HTTP Request (continueOnFail: true)
+  → IF (error occurred)
+    └→ Wait (5 seconds)
+    └→ HTTP Request (retry)
+```
+
+### Pattern 2: Fallback API
+```
+HTTP Request (Primary API, continueOnFail: true)
+  → IF (failed)
+    └→ HTTP Request (Fallback API)
+```
+
+### Pattern 3: Error Trigger Workflow
+**Main Workflow**:
+```
+HTTP Request → Process Data
+```
+
+**Error Workflow**:
+```
+Error Trigger
+  → Set (extract error details)
+  → Slack (alert team)
+  → Database (log error for analysis)
+```
+
+### Pattern 4: Circuit Breaker
+```javascript
+// Code node - circuit breaker logic
+const failures = $json.recentFailures || 0;
+const threshold = 5;
+
+if (failures >= threshold) {
+  throw new Error('Circuit breaker open - too many failures');
+}
+
+return [{ json: { canProceed: true } }];
+```
+
+---
+
+## Response Transformation
+
+### Extract Nested Data
+```javascript
+// Code node
+const response = $input.first().json;
+
+return response.data.items.map(item => ({
+  json: {
+    id: item.id,
+    name: item.attributes.name,
+    email: item.attributes.contact.email
+  }
+}));
+```
+
+### Flatten Arrays
+```javascript
+// Code node - flatten nested array
+const items = $input.all();
+const flattened = items.flatMap(item =>
+  item.json.results.map(result => ({
+    json: {
+      parent_id: item.json.id,
+      ...result
+    }
+  }))
+);
+
+return flattened;
+```
+
+### Combine Multiple API Responses
+```
+HTTP Request 1 (users)
+  → Set (store users)
+  → HTTP Request 2 (orders for each user)
+  → Merge (combine users + orders)
+```
+
+---
+
+## Testing & Debugging
+
+### 1. Test with Manual Trigger
+Replace Schedule with Manual Trigger for testing
+
+### 2. Use Postman/Insomnia First
+- Test API outside n8n
+- Understand response structure
+- Verify authentication
+
+### 3. Log Responses
+```javascript
+// Code node - log for debugging
+console.log('API Response:', JSON.stringify($input.first().json, null, 2));
+return $input.all();
+```
+
+### 4. Check Execution Data
+- View node output in n8n UI
+- Check headers, body, status code
+- Verify data structure
+
+### 5. Use Binary Data Properly
+For file downloads:
+```javascript
+{
+  method: "GET",
+  url: "https://api.example.com/download/file.pdf",
+  responseFormat: "file",  // Important for binary data
+  outputPropertyName: "data"
+}
+```
+
+---
+
+## Performance Optimization
+
+### 1. Parallel Requests
+Use **Split In Batches** with multiple items:
+```
+Set (create array of IDs)
+  → Split In Batches (10 items per batch)
+  → HTTP Request (processes all 10 in parallel)
+  → Loop
+```
+
+### 2. Caching
+```
+IF (check cache exists)
+  ├─ [Cache Hit] → Use cached data
+  └─ [Cache Miss] → HTTP Request → Store in cache
+```
+
+### 3. Conditional Fetching
+Only fetch if data changed:
+```
+HTTP Request (GET with If-Modified-Since header)
+  → IF (status === 304)
+    └─ Use existing data
+  → IF (status === 200)
+    └─ Process new data
+```
+
+### 4. Batch API Calls
+If API supports batch operations:
+```javascript
+{
+  method: "POST",
+  url: "https://api.example.com/batch",
+  bodyParametersJson: JSON.stringify({
+    requests: $json.items.map(item => ({
+      method: "GET",
+      url: `/users/${item.id}`
+    }))
+  })
+}
+```
+
+---
+
+## Common Gotchas
+
+### 1. ❌ Wrong: Hardcoded URLs
+```javascript
+url: "https://api.example.com/prod/users"
+```
+
+### ✅ Correct: Use environment variables
+```javascript
+url: "={{$env.API_BASE_URL}}/users"
+```
+
+### 2. ❌ Wrong: Credentials in parameters
+```javascript
+headerParameters: {
+  "Authorization": "Bearer sk-abc123xyz"  // ❌ Exposed!
+}
+```
+
+### ✅ Correct: Use credentials system
+```javascript
+authentication: "predefinedCredentialType",
+nodeCredentialType: "httpHeaderAuth"
+```
+
+### 3. ❌ Wrong: No error handling
+```javascript
+HTTP Request → Process (fails if API down)
+```
+
+### ✅ Correct: Handle errors
+```javascript
+HTTP Request (continueOnFail: true) → IF (error) → Handle
+```
+
+### 4. ❌ Wrong: Blocking on large responses
+Processing 10,000 items synchronously
+
+### ✅ Correct: Use batching
+```
+Split In Batches (100 items) → Process → Loop
+```
+
+---
+
+## Real Template Examples
+
+From n8n template library (892 API integration templates):
+
+**GitHub to Notion**:
+```
+Schedule → HTTP Request (GitHub API) → Transform → HTTP Request (Notion API)
+```
+
+**Weather to Slack**:
+```
+Schedule → HTTP Request (Weather API) → Set (format) → Slack
+```
+
+**CRM Sync**:
+```
+Schedule → HTTP Request (CRM A) → Transform → HTTP Request (CRM B)
+```
+
+Use `search_templates({query: "http api"})` to find more!
+
+---
+
+## Checklist for API Integration
+
+### Planning
+- [ ] Test API with Postman/curl first
+- [ ] Understand response structure
+- [ ] Check rate limits
+- [ ] Review authentication method
+- [ ] Plan error handling
+
+### Implementation
+- [ ] Use credentials (never hardcode)
+- [ ] Configure proper HTTP method
+- [ ] Set correct headers (Content-Type, Accept)
+- [ ] Handle pagination if needed
+- [ ] Add query parameters properly
+
+### Error Handling
+- [ ] Set continueOnFail: true if needed
+- [ ] Check response status codes
+- [ ] Implement retry logic
+- [ ] Add Error Trigger workflow
+- [ ] Alert on failures
+
+### Performance
+- [ ] Use batching for large datasets
+- [ ] Add rate limiting if needed
+- [ ] Consider caching
+- [ ] Test with production load
+
+### Security
+- [ ] Use HTTPS only
+- [ ] Store secrets in credentials
+- [ ] Validate API responses
+- [ ] Use environment variables
+
+---
+
+## Summary
+
+**Key Points**:
+1. **Authentication** via credentials system (never hardcode)
+2. **Error handling** is critical (continueOnFail + IF checks)
+3. **Pagination** for large datasets
+4. **Rate limiting** to respect API limits
+5. **Transform responses** to match your needs
+
+**Pattern**: Trigger → HTTP Request → Transform → Action → Error Handler
+
+**Related**:
+- [webhook_processing.md](webhook_processing.md) - Receiving HTTP requests
+- [database_operations.md](database_operations.md) - Storing API data