> For the complete documentation index, see [llms.txt](https://docs.spydra.app/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.spydra.app/developers/api-reference/custom-chaincode.md).

# Custom Chaincode

Custom chain codes are programmable code that define the business logic and rules governing the interactions and transactions within a blockchain network.