With cyber threats rising in 2025, front-end developers can no longer ignore security. Common vulnerabilities include XSS, CSRF, and insecure storage of tokens. Best practices: Input Validation: Never trust user inputs—sanitize everything. Secure Cookies & Local Storage: Store tokens safely, avoid sensitive data in localStorage. HTTPS Everywhere: Ensure TLS/SSL certificates are updated. Content Security Policy (CSP): Prevent unauthorized scripts. Regular Updates: Keep dependencies and frameworks patched. Security must be built into the development workflow, not added as an afterthought.