Secure coding principles and practices are fundamental to building resilient products. But if you’re introducing the concept to your team, where should you start?

Here are some key principles and practices every developer should focus on.

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01 – Make ‘Secure by Design’ a priority

Security should be part of the conversation from day one. Building secure systems starts in the planning and design phase, not when code is already being written.

Designing with security in mind safeguards applications, reduces technical debt, creates more maintainable systems, and minimises the risk of costly fixes down the line.

Security–first design thinking ensures a solid foundation for everything that follows.

02 – Embrace the principle of least privilege

How much access does a user, process, or piece of code really need? Asking that question regularly is a great way for developers to build security into their day–to–day thinking.

The principle of least privilege ensures that everything in your system operates with only the permissions it requires. This reduces the risk of accidental misuse, mitigates the impact of potential attacks, and limits the system’s exposure to vulnerabilities.

Building systems where minimal access is the default helps reinforce security at every layer.

03 – Design for strong authentication and authorisation

Authentication (who you are) and authorisation (what you’re allowed to do) are the foundation of secure systems. Making these processes both seamless and secure is essential.

Multi–factor authentication (MFA) provides an added layer of protection, while role–based access control (RBAC) ensures permissions are assigned thoughtfully and appropriately.

Authentication and authorisation are about more than keeping attackers out – they’re also about ensuring legitimate users access only what they need.

04 – Prioritise secure password management

Passwords might not be the most cutting–edge form of security, but they’re still a cornerstone of many systems. Handling them sensibly and securely is critical.

Passwords should always be stored as salted cryptographic hashes – never in plain text. Policies should favour long passwords (over unnecessarily complex ones) and passphrases, and safeguards like account lockouts after repeated failed attempts help prevent brute–force attacks.

Thoughtful password management is a key defence in any security strategy.

05 – Always validate and sanitise user input

Every piece of user input is a potential attack vector. Input validation (done server–side, as client-side controls are too easy to bypass) and sanitisation are essential to preventing injection attacks such as SQL injection or cross–site scripting (XSS).

Allowlists can define what is acceptable, while unexpected inputs should be rejected. Output encoding ensures special characters don’t create vulnerabilities.

This isn’t just about defence – it’s about building robust systems that gracefully handle unexpected input.

06 – Encrypt sensitive data, always

Encryption is essential for protecting sensitive data, whether it’s at rest or in transit. Encryption should be a standard part of any system handling customer information or critical business data.

Established cryptographic libraries and protocols should be used, and encryption keys must be stored separately from the data they protect. It’s also worth considering where sensitive data might be logged or temporarily stored, as these can be overlooked points of exposure.

07 – Build error handling and logging with security in mind

When something goes wrong, how does your system respond? Error handling and logging need to be designed with security in mind.

Error messages should avoid exposing sensitive information, while logs should capture enough data to diagnose issues and monitor for suspicious activity. Logging authentication attempts, failed authorisation requests, and other anomalies is invaluable – but logs themselves must be protected against unauthorised access.

08 – Think long-term

Security isn’t just about today’s threats; it’s about anticipating how decisions will impact the system’s security posture in the future.

Scalable practices, frameworks, and tools with built–in security provide a strong foundation. Regular updates, audits, and iterative improvements ensure the system remains secure as it evolves. A forward–looking approach helps future–proof your applications against emerging threats.

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Secure coding practices aren’t just about avoiding mistakes – they’re about building with security in mind from the very start and maintaining that focus throughout development. Starting with these principles will help your team establish a strong foundation for creating secure, resilient products.