Understanding Token URI: A Comprehensive Guide

Written by
Shivam Srivastava
January 17, 2024
min. read

If you're a dev working in blockchain understanding how token URIs (Uniform Resource Identifier) work is crucial. You'll be dealing with them often. This term, often associated with digital assets and smart contracts, particularly in the context of ERC721 and ERC1155 standards, serves as a bridge between on-chain and off-chain data. Our article delves into all the minute details of Token URI, its functionality, and applications in various frameworks and technologies such as NFTs (Non-Fungible Tokens), Ansible, and OAuth protocols.

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Basics of Token URI

Token URI, at its core, is a reference (a URI) that points to a resource. This resource can be a JSON file, an image, or any other form of data. In the context of blockchain and smart contracts, it primarily refers to the metadata or attributes associated with a specific token.

Token URI in ERC Standards

ERC721 Token URIThe ERC721 standard, a blueprint for creating NFTs, utilizes Token URI to link each unique token to its corresponding metadata. The metadata often includes details like the name, description, and image of the token.


ERC1155 Token URI

In ERC1155, a multi-token standard, the Token URI serves a similar purpose but with an added layer of complexity. It supports both fungible and non-fungible tokens, necessitating a more dynamic approach to linking metadata.

Token URI in NFTs

Role and Structure

In the NFT ecosystem, the Token URI acts as a gateway to the token's details stored off-chain. This design choice helps in reducing on-chain storage requirements and allows for more rich and dynamic content.

Practical Examples

An NFT Token URI might point to a JSON file containing attributes like:

Advanced Use Cases

Setting Token URI in ERC721

To set a Token URI in ERC721, the setTokenURI function can be used. This function updates the URI that points to the token's metadata.


Indirect to Web3 cases:

Token URI is actually not a web3 native concept, is actually more of a general concept in software development and has more to do with how you point to a resource without actually using it in place.

Here’s some more use cases where Token URI is used

Ansible and Token URI

Bearer Token in Ansible

In Ansible, a popular automation tool, the URI module can be used to interact with web services. When dealing with secure endpoints, a bearer token (an authentication token) is often required.

Usage Example

An example playbook using the uri module with a bearer token:

OAuth2 and Token URI

Access Token URI in OAuth2

In OAuth2, an authorization framework, the Access Token URI is a critical endpoint. It's where the application exchanges an authorization code for an access token.

Spring Security Context

Spring Security, a powerful and customizable authentication framework in Java, integrates OAuth2. Here, the access-token-uri property is configured to define the endpoint for token exchange.

Troubleshooting Access Token URI Issues

Common issues like "Access Token URI Not Reached" often stem from misconfigurations or network problems. It's vital to verify endpoint availability and correct configurations.

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FAQ Section

Q1: What is a Base Token URI in Blockchain?

A Base Token URI in blockchain refers to the foundational URL part that is common to all token URIs in a smart contract. It's often used in ERC721 and ERC1155 standards to create a complete Token URI by appending a unique token identifier to this base URL.

Q2. How is a Bearer Token Used in Ansible URI?

In Ansible, a bearer token is used for authentication when making API requests using the URI module. It's included in the header of a request to ensure secure access to a web service, as demonstrated in the playbook example provided in the article.

Q3: What is Security.oauth2.client.access-token-uri in Spring Security?

In Spring Security, security.oauth2.client.access-token-uri is a configuration property used in OAuth2 client setups. It specifies the endpoint URL where the application can exchange an authorization code for an access token.

Q4: How Does ERC721 Set Token URI Function Work?

In ERC721, the setTokenURI function is used to assign or update the URI that points to a specific token's metadata. This function allows for dynamic setting or updating of the metadata link associated with a token.

Q5: What are Common Issues Related to Access Token URI in OAuth?

Common issues related to the Access Token URI in OAuth include network connectivity problems, misconfigurations of the endpoint, or incorrect client credentials. These problems can prevent successful token retrieval in OAuth flows.

Q6: How to Troubleshoot 'Access Token URI Not Reaching' Issues?

To troubleshoot issues where the access token URI is not reachable, check the network connectivity, validate the endpoint URL, ensure proper client credential configurations, and verify if the OAuth server is operational.


Token URI is a pivotal concept in web technologies and modern blockchain. In the world of blockchain specifically It facilitates a seamless integration of on-chain and off-chain data, ensuring a flexible and efficient system. From NFTs to automation tools.