# ERC-721F
The ERC-721F is a variant of the ERC-721 standard developed by Xyxyx.
ERC-721F is designed to provide highly customizable token issuance by assigning each token an individualized SVG output at the time of minting.
* [Parameters](/token-standards/erc-721f/parameters.md)
* [ERC-721F GitHub Repository](https://github.com/xyxyxpro/ERC-721F/)
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### Introduction to ERC-721F
Traditional ERC-721 contracts operate under a monolithic token metadata architecture. Token URIs are either hardcoded into the smart contract or derived through deterministic logic, which limits the ability to introduce per-token variability. Moreover, reliance on off-chain resources such as IPFS introduces issues related to availability, mutability, and provenance.
Built by Xyxyx, the ERC-721F standard takes a fundamentally different approach. By delegating metadata construction to the `mint` function — and by allowing external systems to inject token-specific metadata at runtime — the standard promotes a modular and extensible architecture. For that, the ERC-721F integrates native Base64 encoding within the `tokenURI` schema as default.
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### **svgString**
The core functionality of ERC-721F is a parameter called `svgString`, which is encapsulated in the `mint` function. `svgString` permits the definition of `tokenURI`s at the time of token issuance, bypassing traditional metadata bottlenecks.
As a result, ERC-721F enables the creation of highly customized and self-contained tokens that, on the one hand, do not depend on off-chain infrastructure for data storage and, on the other hand, can be composable with any existing external system for data input.
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### ERC-721F and Xyxyx API
Unlike traditional ERC-721 contracts where the metadata URI is statically embedded, ERC-721F delegates metadata construction to external systems through the minting process. This design principle reflects a modular and extensible architecture, where third-party applications can dynamically determine token characteristics at runtime.
The ERC-721F standard is designed for seamless integration with the [Xyxyx API](/products-and-services/api.md), a REST API developed to automate and simplify the creation of contract deployments and injection of `svgString` values during the minting process.
By leveraging the Xyxyx API, the ERC-721F can be leveraged to programmatically generate and assign complex on-chain metadata to tokens, reducing the need for manual metadata construction and enabling integration with any existing system.
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### Conclusion
By decoupling metadata from rigid contract logic and empowering external systems to participate in metadata construction, ERC-721F provides advancements in modularity, extensibility, and metadata composability with any existing system.
Through ERC-721F, smart contracts no longer dictate the entirety of token metadata. Instead, they serve as programmable shells into which structured, dynamic data can be injected by any existing system — unlocking a wide range of potential interactions and designs.
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