Writing Secure Code: Best Practices for Beginners

Every line of code you write is a potential security risk. A missing input check or an outdated library can be all it takes for an attacker to slip in — not through brute force, but through your code itself.

In today’s digital world, writing code isn’t just about making apps or websites work. It’s about making them safe. Cyberattacks, data breaches and stolen information are becoming increasingly common, and even small mistakes in your code can open doors for hackers.

The good news?
You don’t need to be an expert to write secure code. By building the right habits early, you can protect your users and your future projects… from day one. Here are some essential best practices for writing secure code:

1. Validate All Input

Never trust user input. Anything a user can submit; forms, URLs or API requests can potentially be malicious. Always validate and sanitize inputs to prevent attacks like SQL injection or cross-site scripting (XSS).

Tip: Use whitelisting (allow only what’s expected) instead of blacklisting (blocking known bad inputs).

// ❌ bad:
const query = SELECT * FROM users WHERE name = '${userInput}';

// ✅ good:
const query = SELECT * FROM users WHERE name = ?; db.query(query, [userInput]);

2. Use Strong Authentication & Authorization

Authentication confirms who a user is; authorization determines what they can do. Implement strong passwords, consider multi-factor authentication (MFA) and make sure users can access only what they’re allowed.

Example: Role-based access control ensures an admin can edit user accounts, but a regular user cannot.

3. Keep Dependencies Updated

Modern apps often rely on libraries and frameworks. Using outdated or vulnerable packages is like leaving a door unlocked for hackers.

Tip: Regularly check for security updates using tools like npm audit for Node.js or pip-audit for Python.

4. Handle Errors Safely

Errors happen. But exposing stack traces or sensitive information to users can give attackers clues about your system. Always handle errors gracefully and log them securely for debugging purposes.

Tip: In production, never reveal database details, file paths, or API keys in error messages.
Instead, log detailed error information securely on the server for your debugging purposes, but show generic, user-friendly messages to end users. For example, instead of displaying:

A bad example:

DatabaseError: Connection failed at /var/www/app/db.py line 42

A better example:

Oops! Something went wrong. Please try again later.

5. Protect Sensitive Data

Passwords, personal information, and API keys must never be stored in plain text. Use encryption for storage and secure channels like HTTPS for transmission. Avoid hardcoding secrets directly in your code use environment variables instead.

Tip: Always encrypt sensitive information and separate secrets from your code.

Begin by understanding that anything stored or transmitted without protection is vulnerable. For passwords, never store them in plain text. Use strong hashing algorithms like bcrypt or Argon2

6. Follow the Principle of Least Privilege

Give users and programs only the access they absolutely need. Limiting permissions reduces the impact if credentials are compromised.

Tip: Give every user and service the minimum access they need, and audit permissions regularly.

The principle of least privilege is simple in concept but powerful in practice. Every user account, application or service should only have the access necessary to perform its specific task

7. Write Testable, Maintainable Code

Security is easier to maintain when your code is clean and testable. Peer reviews, automated testing and static code analysis tools help catch vulnerabilities early.

Conclusion

Secure coding isn’t about perfection… it’s about cultivating the right habits. By validating input, controlling access, protecting data and staying vigilant, you can dramatically reduce risks, even as a beginner.

Start small, practice consistently and remember: writing secure code is a mindset, not a one-time task. The sooner you adopt these practices, the stronger your coding foundation will be and the safer the software you build.

If you’ve got your own coding security habits or small tricks you swear by, drop them in the comments I’d love to learn from your perspective too. thanks for reading this far 🙏🏾