> For the complete documentation index, see [llms.txt](https://docs.frequencychain.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.frequencychain.org/16.-best-practices-security-and-production-readiness/16.1-smart-contract-security.md).

# 16.1 Smart Contract Security

Smart contracts form the core logic of decentralized applications, and once deployed, they are immutable. This makes it critical to ensure correctness and security before deployment.

Developers must ensure that contracts are designed to prevent unauthorized access and unintended state changes. Functions that modify critical state should include explicit validation checks to restrict execution to authorized entities. This is typically implemented using access control patterns where specific wallet addresses or roles are granted permissions.

All external inputs must be treated as untrusted. Contracts should validate input parameters rigorously to prevent invalid state transitions. This includes checking value ranges, ensuring correct data formats, and handling edge cases explicitly.

Special attention must be given to functions that handle value transfer. Improper implementation can expose contracts to vulnerabilities such as reentrancy. Developers should follow established patterns such as updating state before transferring funds and using appropriate safeguards when interacting with external contracts.

Before deployment, contracts should be thoroughly tested using both unit tests and integration tests. In addition, formal audits and peer reviews are strongly recommended for any contract handling significant value.


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