lindy-sdk-patterns

Lindy SDK & Integration Patterns

Overview

Lindy is primarily a no-code platform. External integration happens through three channels: Webhook triggers (inbound), HTTP Request actions (outbound), and Run Code actions (inline Python/JS execution via E2B sandbox). This skill covers patterns for each.

Prerequisites

• Lindy account with active agents
• Node.js 18+ or Python 3.10+ for webhook receivers
• Completed lindy-install-auth setup

Pattern 1: Webhook Trigger Integration

Your application fires webhooks to wake Lindy agents:

// lindy-client.ts — Reusable Lindy webhook trigger client
class LindyClient {
  private webhookUrl: string;
  private secret: string;

  constructor(webhookUrl: string, secret: string) {
    this.webhookUrl = webhookUrl;
    this.secret = secret;
  }

  async trigger(payload: Record<string, unknown>): Promise<{ status: number }> {
    const response = await fetch(this.webhookUrl, {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${this.secret}`,
        'Content-Type': 'application/json',
      },
      body: JSON.stringify(payload),
    });

    if (!response.ok) {
      throw new Error(`Lindy webhook failed: ${response.status} ${response.statusText}`);
    }

    return { status: response.status };
  }

  async triggerWithCallback(
    payload: Record<string, unknown>,
    callbackUrl: string
  ): Promise<{ status: number }> {
    return this.trigger({ ...payload, callbackUrl });
  }
}

// Usage
const lindy = new LindyClient(
  'https://public.lindy.ai/api/v1/webhooks/YOUR_ID',
  process.env.LINDY_WEBHOOK_SECRET!
);

await lindy.trigger({ event: 'lead.created', name: 'Jane Doe', email: '[email protected]' });

Pattern 2: HTTP Request Action (Agent Calling Your API)

Configure a Lindy agent to call your API as an action step:

In Lindy Dashboard — Add HTTP Request action:

• Method: POST
• URL: https://api.yourapp.com/process
• Headers: Authorization: Bearer {{your_api_key}}, Content-Type: application/json
• Body (AI Prompt mode):

  Send the processed data as JSON with fields matching the API schema.
  Include: name from {{trigger.data.name}}, analysis from previous step.
  

Your API endpoint receives the call:

// Your API receiving Lindy agent calls
app.post('/process', async (req, res) => {
  const { name, analysis } = req.body;
  const result = await processData(name, analysis);
  res.json({ result, processedAt: new Date().toISOString() });
});

Pattern 3: Run Code Action (E2B Sandbox)

Execute Python or JavaScript directly in Lindy workflows. Code runs in isolated Firecracker microVMs with ~150ms startup time.

Python example (data transformation in a workflow):

# Run Code action — Python
# Input variables: raw_data (string from previous step)
import json

data = json.loads(raw_data)  # Input vars are always strings

# Process
cleaned = [
    {"name": item["name"].strip(), "score": float(item["score"])}
    for item in data["items"]
    if float(item["score"]) > 0.5
]

# Sort by score descending
cleaned.sort(key=lambda x: x["score"], reverse=True)

# Return value accessible as {{run_code.result}} in next step
return json.dumps({"filtered_count": len(cleaned), "items": cleaned})

JavaScript example (API call + processing):

// Run Code action — JavaScript
// Input variables: query (string), api_key (string)
const response = await fetch(`https://api.example.com/search?q=${query}`, {
  headers: { 'Authorization': `Bearer ${api_key}` }
});
const data = await response.json();

const summary = data.results.map(r => `${r.title}: ${r.snippet}`).join('\n');
return JSON.stringify({ count: data.results.length, summary });

Run Code outputs (available to subsequent steps):

Output	Contents
{{run_code.result}}	Value from return statement
{{run_code.text}}	stdout from print() / console.log()
{{run_code.stderr}}	Error output for debugging

Available Python libraries: pandas, numpy, scipy, scikit-learn, matplotlib, requests, aiohttp, beautifulsoup4, nltk, spacy, openpyxl, python-docx

Key constraint: All input variables arrive as strings. Cast explicitly: count = int(count_str), data = json.loads(json_str)

Pattern 4: Callback Pattern (Async Two-Way)

Send a callbackUrl in your webhook payload. Lindy can respond back using the Send POST Request to Callback action:

// Your app triggers Lindy with a callback URL
await lindy.trigger({
  event: 'analyze.request',
  data: { text: 'Analyze this quarterly report...' },
  callbackUrl: 'https://api.yourapp.com/lindy-callback'
});

// Your callback handler receives Lindy's response
app.post('/lindy-callback', (req, res) => {
  const { analysis, sentiment, summary } = req.body;
  saveAnalysis(analysis);
  res.sendStatus(200);
});

Pattern 5: Retry with Exponential Backoff

async function triggerWithRetry(
  client: LindyClient,
  payload: Record<string, unknown>,
  maxRetries = 3
): Promise<void> {
  for (let attempt = 0; attempt <= maxRetries; attempt++) {
    try {
      await client.trigger(payload);
      return;
    } catch (error: any) {
      if (attempt === maxRetries) throw error;
      const delay = Math.pow(2, attempt) * 1000; // 1s, 2s, 4s
      console.warn(`Retry ${attempt + 1}/${maxRetries} in ${delay}ms`);
      await new Promise(r => setTimeout(r, delay));
    }
  }
}

Error Handling

Pattern	Failure Mode	Solution
Webhook trigger	401 Unauthorized	Verify Bearer token matches dashboard secret
HTTP Request action	Target API unreachable	Check URL, verify HTTPS, test with curl
Run Code	Timeout	Avoid infinite loops; keep execution under 30s
Run Code	Import error	Use only pre-installed libraries (see list above)
Callback	Callback URL unreachable	Ensure HTTPS endpoint is publicly accessible

Resources

• Calling Any API
• Run Code Documentation
• Webhooks Documentation

Next Steps

Proceed to lindy-core-workflow-a for full agent creation workflows.