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How to Secure a React App
Protect your React application with these essential techniques.
React is a powerful frontend framework, but it comes with its own security considerations. This guide covers the most important React security measures: XSS prevention, CSRF protection, environment variables, and secure authentication.
150+
Security checks
16
Categories covered
30s
Scan duration
100%
Detection coverage
Key Findings
Missing CSRF Protection high
Insecure Dependencies medium
1. Prevent XSS in React
React automatically escapes content in JSX, preventing most XSS attacks. However, `dangerouslySetInnerHTML` bypasses this protection. Never use it with unsanitized user input. Always sanitize HTML using a library like `DOMPurify` before setting `innerHTML`. Validate and encode URLs to prevent `javascript:` protocol attacks.
2. CSRF Protection in React
CSRF attacks target server‑side endpoints, not the React frontend. Use `SameSite=Lax` or `Strict` cookies. Include CSRF tokens in `fetch` or `axios` headers. Many server frameworks (Django, Laravel) provide CSRF tokens that you can include in a `` tag or a global variable.
3. Environment Variables in React
Only `REACT_APP_*` variables are embedded in the build. Never put secrets in these variables – they are visible in the browser. Use server‑side environment variables for sensitive data. For API keys, proxy requests through your backend.
4. Secure Authentication
Use HTTP‑only cookies for session tokens, not `localStorage` or `sessionStorage` (which are vulnerable to XSS). Implement JWT with short expiry and refresh tokens. Use secure cookies with `Secure`, `HttpOnly`, and `SameSite` flags. OffURL can detect if your React app uses insecure token storage.
The Problem
React apps often expose sensitive data or are vulnerable to attacks
- Using `dangerouslySetInnerHTML` with unsanitized content
- No CSP header to prevent XSS
- Insecure storage of tokens (localStorage)
- Exposed environment variables
- Missing CSRF protection
OffURL Solution
OffURL detects React-specific vulnerabilities and provides fix steps
- Check for XSS patterns in rendered HTML
- Detect insecure token storage
- Verify CSP headers
- Check for exposed environment variables
- Generate an LLM‑ready PDF for AI‑assisted fixes
Key Features
React detection
We detect if your site uses React.
XSS patterns
We scan for dangerous `dangerouslySetInnerHTML` patterns.
Token storage check
We detect if tokens are stored in localStorage.
LLM‑ready PDF
Get a report formatted for ingestion into your AI assistant.
How do I check if my React app is secure?
Run an OffURL audit. Our scanner checks for common React vulnerabilities including XSS, insecure token storage, CSP headers, and environment variable exposure. You'll get a detailed report with specific fix steps.
Frequently Asked Questions
What is OffURL and how does it work?
OffURL is a comprehensive website security and performance audit tool. It scans your site for 150+ checks including SSL, security headers, malware, XSS, SQL injection, email security, and more.
Is the security audit really free?
Yes. Your first security report is completely free and includes premium features like detailed findings, fix steps, and the full 150+ checks.
How can I use AI to fix security issues?
Download the premium PDF report and paste it into your preferred LLM (Claude, ChatGPT, Gemini, Cursor) with a prompt asking for specific fixes for your framework.
How long does the security audit take?
Most audits complete in 10‑30 seconds. The scan includes DNS lookups, SSL analysis, HTTP requests, port scanning, and vulnerability tests.
Do I need to create an account?
No. OffURL works without registration. Your first audit is free with premium features included.
What vulnerabilities can OffURL detect?
OffURL detects XSS, SQL Injection, NoSQL Injection, LDAP Injection, XXE, SSRF, SSTI, Code Injection, Command Injection, Open Redirect, Path Traversal, LFI, RFI, CRLF Injection, Parameter Pollution, and CORS Misconfiguration.