Flow Namespace - Chains

CAIP-2

For context, see the CAIP-2 specification.

Introduction

The Flow namespace uses short, human-readable network identifiers. These identifiers are stable and map to distinct Flow networks.

Specification

Semantics

A valid Flow CAIP-2 identifier takes the form:

flow:<network>

Where <network> is one of the following reserved identifiers:

• mainnet
• testnet

Syntax

Regular Expression

^flow:(mainnet|testnet)$

Example

flow:mainnet

Resolution Mechanics

Clients should resolve a Flow network identifier by querying the Flow REST API network parameters endpoint for the target network and verifying the returned chain_id.

Sample request (mainnet):

GET https://rest-mainnet.onflow.org/v1/network/parameters

Sample response:

{
  "chain_id": "flow-mainnet"
}

Rationale

Stable, human-readable network names provide a simple and consistent way to identify Flow networks across tooling.

Backwards Compatibility

There are no legacy identifiers for Flow networks in this namespace.

Test Cases

• Flow Mainnet: flow:mainnet
• Flow Testnet: flow:testnet

References

• Flow - Official Flow website and documentation portal.
• CAIP-2 - Chain ID Specification.

Copyright

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Hao Fu, "namespaces/flow-caip2: Flow Namespace - Chains [DRAFT]," Chain Agnostic Namespaces, flow-caip2, January 2026 / . [Online serial]. Available: https://github.com/ChainAgnostic/namespaces/flow-caip2.md