Firecrawl Security Basics Skill

Firecrawl Security Basics

Overview

Security best practices for Firecrawl API keys, webhook signature verification, and scraped content handling. Firecrawl API keys start with fc- and grant full access to scrape, crawl, map, and extract endpoints — protecting them is critical.

Prerequisites

Firecrawl API key
Understanding of environment variables
Webhook endpoint (if using async crawl callbacks)

Instructions

Step 1: Secure API Key Storage

# .env (NEVER commit to git)
FIRECRAWL_API_KEY=fc-your-api-key-here

# .gitignore — add these patterns
echo -e "\n.env\n.env.local\n.env.*.local" >> .gitignore

// Validate key exists before creating client
import FirecrawlApp from "@mendable/firecrawl-js";

if (!process.env.FIRECRAWL_API_KEY?.startsWith("fc-")) {
  throw new Error("FIRECRAWL_API_KEY must be set and start with 'fc-'");
}

const firecrawl = new FirecrawlApp({
  apiKey: process.env.FIRECRAWL_API_KEY,
});

Step 2: Verify Webhook Signatures

Firecrawl signs webhook payloads with HMAC-SHA256 via the X-Firecrawl-Signature header.

import crypto from "crypto";

function verifyWebhookSignature(
  payload: string,
  signature: string,
  secret: string
): boolean {
  const expected = crypto
    .createHmac("sha256", secret)
    .update(payload)
    .digest("hex");

  // Timing-safe comparison prevents timing attacks
  return crypto.timingSafeEqual(
    Buffer.from(signature),
    Buffer.from(expected)
  );
}

// Express webhook handler with verification
app.post("/webhooks/firecrawl", (req, res) => {
  const signature = req.headers["x-firecrawl-signature"] as string;
  const rawBody = JSON.stringify(req.body);

  if (!verifyWebhookSignature(rawBody, signature, process.env.FIRECRAWL_WEBHOOK_SECRET!)) {
    console.error("Invalid webhook signature — rejecting");
    return res.status(401).json({ error: "Invalid signature" });
  }

  // Process verified webhook
  const { type, data } = req.body;
  console.log(`Verified webhook: ${type}`);
  res.status(200).json({ received: true });
});

Step 3: Separate Keys per Environment

# GitHub Actions secrets
gh secret set FIRECRAWL_API_KEY_DEV --body "fc-dev-..."
gh secret set FIRECRAWL_API_KEY_STAGING --body "fc-staging-..."
gh secret set FIRECRAWL_API_KEY_PROD --body "fc-prod-..."

// Load correct key based on environment
const KEY_MAP: Record<string, string> = {
  development: "FIRECRAWL_API_KEY_DEV",
  staging: "FIRECRAWL_API_KEY_STAGING",
  production: "FIRECRAWL_API_KEY_PROD",
};

const envVar = KEY_MAP[process.env.NODE_ENV || "development"];
const apiKey = process.env[envVar] || process.env.FIRECRAWL_API_KEY;

Step 4: Rotate Keys

set -euo pipefail
# 1. Generate new key at firecrawl.dev/app
# 2. Deploy new key alongside old key
# 3. Verify new key works
curl -s https://api.firecrawl.dev/v1/scrape \
  -H "Authorization: Bearer $NEW_FIRECRAWL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com","formats":["markdown"]}' | jq .success

# 4. Remove old key from all environments
# 5. Delete old key in Firecrawl dashboard

Step 5: Sanitize Scraped Content

// Scraped web content may contain PII, scripts, or malicious data
function sanitizeScrapedContent(markdown: string): string {
  return markdown
    // Remove potential script injections
    .replace(/<script[\s\S]*?<\/script>/gi, "")
    // Remove data URIs (potential XSS vectors)
    .replace(/!\[.*?\]\(data:.*?\)/g, "")
    // Remove javascript: links
    .replace(/\[.*?\]\(javascript:.*?\)/g, "")
    // Strip HTML comments
    .replace(/<!--[\s\S]*?-->/g, "")
    .trim();
}

Security Checklist

[ ] API key stored in environment variable, never hardcoded
[ ] .env files listed in .gitignore
[ ] Different keys for dev/staging/production
[ ] Webhook signatures verified before processing
[ ] Scraped content sanitized before storage/display
[ ] Key rotation scheduled quarterly
[ ] Git history scanned for leaked keys

Error Handling

| Security Issue | Detection | Mitigation | |----------------|-----------|------------| | Leaked API key in git | git log -p \| grep "fc-" | Rotate immediately, revoke old key | | Invalid webhook signature | Signature verification fails | Reject request, alert team | | Excessive scraping costs | Credit alerts from Firecrawl | Set credit limits per key | | PII in scraped content | Content scanning | Sanitize before storage |

Resources

Next Steps

For production deployment, see firecrawl-prod-checklist.

Agent Skills: Firecrawl Security Basics

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