> For the complete documentation index, see [llms.txt](https://docs.catddle.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.catddle.com/technology/erc721-o.md).

# ERC721-O

ERC721-O is a standard interface and implementation for omnichain non-fungible tokens (NFT) based on ERC721.

It aims to allow third-party applications (e.g., wallet/marketplace) to interact with any token implemented in this interface uniformly.

It also enables the implementation of multiple new features and proposed solutions to mitigate security issues in the cross-chain domain.

You can find our [full introduction](https://catddle.medium.com/erc721o-e6c9a0ae09e1) here.