> ## Documentation Index
> Fetch the complete documentation index at: https://docs.safefoundation.org/llms.txt
> Use this file to discover all available pages before exploring further.
# Guards
> Add programmable pre- and post-execution checks to Safe Smart Accounts to enforce custom transaction restrictions.
Safe Guards were introduced in
[Safe contracts version 1.3.0](https://github.com/safe-fndn/safe-smart-account/blob/v1.3.0/CHANGELOG.md).
Safe Guards add an additional security layer on top of Safe’s `n`-out-of-`m` multi-signature scheme. They allow Safe owners to define **custom rules** that determine whether a transaction should be allowed to execute.
A Safe Guard can perform checks:
* **Before execution**, to validate the transaction parameters and context
* **After execution**, to verify the final state of the Safe once the transaction has completed
Pre-execution checks can inspect all transaction parameters—such as the target address, calldata, value, and operation type—and decide whether the transaction should proceed.\
Post-execution checks run at the end of the transaction and can be used to assert invariants or detect unexpected state changes.
Guards are commonly used to:
* restrict interactions to approved contracts
* enforce protocol-specific invariants
* add additional safety checks around sensitive operations
To explore real-world examples of Safe Guards, see:
* [Zodiac Guard implementations](https://github.com/gnosis/zodiac-guard-scope)
* [Yearn Guard design](https://mirror.xyz/yearn-finance-engineering.eth/9uInM_sCrogPBs5qkFSNF6qe-32-0XLN5bty5wKLVqU)
Important: Safe Guards are security-critical. Because a Guard
can block transaction execution entirely, a faulty or malicious Guard can
cause a denial of service and lock funds in a Safe. Only use well-reviewed and
audited Guards, and always consider recovery mechanisms.