Aptos Namespace - Chains

CAIP-2

For context, see the CAIP-2 specification.

Rationale

In CAIP-2 a general blockchain identification scheme is defined. This is the implementation of CAIP-2 for Aptos. Blockchains in the “aptos” namespace are identified by their numeric chain_id, assigned at genesis. Each network is maintained by a set of validators with its own REST API endpoints. These chain IDs require no transformations to be used as conformant CAIP-2 references.

Syntax

The namespace “aptos” refers to the Aptos open-source blockchain platform.

Reference Definition

The definition for this namespace will use the chain_id as an identifier for different Aptos chains. The chain ID is a positive integer assigned at genesis:

Resolution Method

To resolve a blockchain reference for the Aptos namespace, make an HTTP GET request to the REST API of a fullnode, for example:

curl https://fullnode.mainnet.aptoslabs.com/v1

// Response
{
  "chain_id": 1,
  "epoch": "5000",
  "ledger_version": "500000000",
  "oldest_ledger_version": "0",
  "ledger_timestamp": "1700000000000000",
  "node_role": "full_node",
  "oldest_block_height": "0",
  "block_height": "100000000",
  "git_hash": "abc123..."
}

The response will return chain_id as an integer that can be used directly as the CAIP-2 reference.

Backwards Compatibility

Not applicable

Test Cases

This is a list of manually composed examples

# Aptos Mainnet
aptos:1

# Aptos Testnet
aptos:2

References

• REST API - REST API reference in Aptos official documentation
• Aptos core rust crate on crates.io
• Networks - Aptos network information and endpoints

Copyright

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Jon Tang, "namespaces/aptos-caip2: Aptos Namespace - Chains [DRAFT]," Chain Agnostic Namespaces, aptos-caip2, December 2025 / December 2025. [Online serial]. Available: https://github.com/ChainAgnostic/namespaces/aptos-caip2.md