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.

firecrawl-security-basics

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