Security should never be an afterthought.
Whether you’re building a custom plugin, theme, or REST API, security needs to be part of every development decision.
Here are the practices I follow when developing WordPress projects.
1. Never Trust User Input
Every value coming from users should be considered untrusted.
Always validate and sanitize data before processing it.
Common sanitization functions include:
- sanitize_text_field()
- sanitize_email()
- sanitize_key()
- absint()
- sanitize_textarea_field()
Clean input helps prevent unexpected behavior and security vulnerabilities.
2. Escape Output
Escaping protects your application when displaying dynamic content.
Use the correct escaping function for the context.
Examples include:
- esc_html()
- esc_attr()
- esc_url()
- wp_kses_post()
Always escape as late as possible, just before output.
3. Protect Forms with Nonces
Every form that performs an action should include a nonce.
This protects against Cross-Site Request Forgery (CSRF) attacks.
Always verify the nonce before processing requests.
4. Check User Permissions
Never assume a logged-in user has permission to perform an action.
Always verify capabilities using functions like:
- current_user_can()
Permission checks should happen before executing sensitive operations.
5. Use Prepared Database Queries
Never build SQL queries by concatenating user input.
Always use prepared statements when working with custom database queries.
Prepared queries protect against SQL injection attacks.
6. Secure REST API Endpoints
Every custom endpoint should define proper permission callbacks.
Only expose data that users are allowed to access.
Avoid returning unnecessary information.
7. Upload Files Safely
File uploads require additional validation.
Always verify:
- File type
- File size
- Allowed extensions
- Upload permissions
Never trust the file extension alone.
8. Load Dependencies Carefully
Only install trusted plugins and Composer packages.
Keep all dependencies updated.
Remove packages that are no longer required.
Outdated software is one of the most common security risks.
9. Follow WordPress Coding Standards
Consistent code is easier to review and less likely to introduce vulnerabilities.
Using WordPress Coding Standards also improves collaboration with other developers.
10. Keep Security Continuous
Security is not something you implement once.
Review your code regularly.
Update dependencies.
Audit permissions.
Monitor logs.
Test your applications after every major release.
Final Thoughts
Secure WordPress development is built on consistent habits rather than complex tools.
Small decisions like validating input, escaping output, checking permissions, and writing clean code make a significant difference over the lifetime of a project.
Building secure applications starts with writing secure code.