HIP-20: Standardized URI scheme to reference Hedera data Source

AuthorKhoa Luong, Sam Wood, Stephanie Yi, Declan Fox
Needs Council ApprovalYes
TypeStandards Track
Superseded by30


This HIP defines a way for Hedera to host data in a centralized location and accessible with a standardized URI.


Non-fungible tokens often have metadata associated with them and this HIP provides a way to access them with a standardized URI, hosted by Hedera. Third-party applications would then be able to use this standardized URI to integrate with and display a token’s metadata and image (for example: DECENT Wallet [0]). Non-Hedera NFT’s could also utilize this feature to host their metadata, like ERC-721.


The format of the URI includes the prefix “hcs” to represent that it is hosted on Hedera, and then the network that the token was deployed on (mainnet/testnet), followed by the topic ID. Currently, Hedera’s ID convention can be confusing because a topic ID on one network can be a wallet ID in another network, so by using this prefix, we can start standardizing the format of the IDs. For example, using HCS to distinguish data hosted on Hedera consensus service, HFS prefix for Hedera file service, as well as including the associated network (testnet, previewnet).

One use case for the topic ID to be part of the URI is: the metadata of an NFT can be submitted to this topic as a message and then retrieved by accessing this standardized URI. This gives us an easy way to send the token’s metadata to Hedera without the need for a new API. The token’s metadata URI would then be stored on the memo field of the token when it is deployed.


Different Hedera services have different prefixes, for example, HFS for Hedera file service and HCS for Hedera consensus service. The URI is in the following format: hcs-:// for testnet and previewnet and hcs:// for mainnet. For example: hcs-testnet://0.0.01234. This URI then serve the metadata in the format of the "Token Metadata JSON Schema", from HIP-10 [1]. For Hedera file service, the format is: hfs:// and hfs-{}://

Backwards Compatibility

This feature is optional for deployed Hedera tokens so there won’t be any backward compatibility concerns.

Security Implications

No known security concerns.

How to Teach This

Reference Implementation

Rejected Ideas

Open Issues


[0] https://dcentwallet.com/features/erc721-wallet [1] https://github.com/hashgraph/hedera-improvement-proposal/blob/master/HIP/hip-10.md


This document is licensed under the Apache License, Version 2.0 – see LICENSE or (https://www.apache.org/licenses/LICENSE-2.0)


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