Tron Namespace - Blockchain ID Specification

CAIP-2

For context, see the CAIP-2 specification.

Rationale

Tron chain IDs are derived from the last 4 bytes of the genesis block hash, as specified in TIP-474, and are expressed in decimal, following the same convention as the eip155 namespace. This approach provides several benefits:

• Deterministic derivation from the immutable genesis block
• Compatibility with EVM tooling and infrastructure
• Replay protection across different Tron networks
• Integration with existing blockchain registries like ChainList

The chain ID mechanism was introduced to enable cross-chain compatibility and provide unique, verifiable identifiers for each Tron network.

Syntax

The namespace “tron” refers to the Tron blockchain platform and its associated networks.

Reference Definition

The reference format for Tron chains is the decimal representation of the chain ID, an unsigned 32-bit integer. This chain ID is the numeric value of the last 4 bytes of the genesis block hash.

Format: tron:{chainId} where chainId is the chain ID rendered in decimal, without leading zeroes

Semantics

The chain ID derivation follows this algorithm:

1. Query the genesis block (block height 0)
2. Extract the block hash
3. Take the last 4 bytes (8 hexadecimal characters) of the genesis block hash
4. Interpret those 4 bytes as a big-endian unsigned 32-bit integer
5. Render that integer in decimal

Resolution Method

Tron chain IDs are derived from the last 4 bytes of the genesis block hash and are static for each network. Applications should use the following pre-determined chain IDs:

These chain IDs are deterministically derived and do not change. For verification purposes, you can query the genesis block to confirm the derivation, but the chain IDs themselves are constants that should be used for network identification.

These values are published by the Tron Foundation in Tron Developer Hub - eth_chainId, which is the authoritative source should the table above fall out of date. They can also be confirmed at any time by calling eth_chainId or reading the genesis block on each network.

Note: Applications should use Tron-native RPC methods with the tron_ prefix (e.g., tron_getBalance, tron_signTransaction). While Tron implements some EVM-compatible JSON-RPC endpoints (including eth_chainId) for tooling compatibility, these are secondary interfaces. The chain ID values remain the same regardless of which RPC interface is used.

When resolving via eth_chainId, the response is a base-16-encoded integer (e.g. 0x2b6653dc) and must be converted to base 10 to form a CAIP-2 reference, as in the eip155 namespace.

Test Cases

This is a list of manually composed and validated examples:

# Tron Mainnet
tron:728126428

# Tron Shasta Testnet (mainnet-compatible testing)
tron:2494104990

# Tron Nile Testnet (bleeding-edge features)
tron:3448148188

Chain ID Verification

The hexadecimal column is informative only; it shows the derivation from the genesis hash and is not a valid CAIP-2 reference.

RPC Endpoints for Resolution

The endpoints below are operated as part of TronGrid, the TRON network’s hosted node service, which exposes JSON-RPC alongside its FullNode, SolidityNode and gRPC interfaces. Rather than treating this list as normative, implementers should consult the official documentation, which is the authoritative and maintained source: TronGrid for the service itself, and Networks for the per-network endpoints.

• Mainnet: https://api.trongrid.io/jsonrpc
• Shasta: https://api.shasta.trongrid.io/jsonrpc
• Nile: https://nile.trongrid.io/jsonrpc

Note that TronGrid applies rate limits and expects an API key for production use; see the TronGrid documentation for current terms.

Backwards Compatibility

Prior to TIP-474, Tron did not have a standardized chain ID mechanism for cross-chain identification.

Both a decimal and a 0x-prefixed hexadecimal rendering of the same 4-byte value have circulated in the ecosystem. This specification designates the decimal form as canonical, which keeps the namespace consistent with:

• The underlying type of the chain ID, which TIP-474 and the CHAINID opcode treat as an integer rather than a byte string
• Tron’s existing registrations in ethereum-lists/chains and ChainList (728126428 for Mainnet)
• Existing wallet implementations, including MetaMask and tronwallet-adapter
• The eip155 namespace, which uses decimal references

The decimal form was agreed as the canonical CAIP-2 representation for Tron in TRON Wallet Dev Community Call #5 on 2026-08-19; see tronprotocol/pm#229.

Implementations that previously emitted the hexadecimal form should treat it as a deprecated alias: accept tron:0x2b6653dc on input, normalise it to tron:728126428, and emit only the decimal form. The underlying chain ID value is unchanged, so no address-level or on-chain migration is required.

Additional Considerations

Genesis Block Hash Format

The full genesis block hashes for reference:

Mainnet:

0x00000000000000001ebf88508a03865c71d452e25f4d51194196a1d22b6653dc

Shasta Testnet:

0x0000000000000000de1aa88295e1fcf982742f773e0419c5a9c134c994a9059e

Nile Testnet:

0x0000000000000000d698d4192c56cb6be724a558448e2684802de4d6cd8690dc

Registry Information

Tron chain IDs are registered in:

• ChainList: Public registry of EVM and EVM-compatible chains
• ChainID.network: Community-maintained chain ID database

Network Selection

Applications should use:

• Mainnet for production deployments
• Shasta for testing with mainnet-compatible parameters
• Nile for testing bleeding-edge features before mainnet deployment

References

• CAIP-2: Chain ID Specification
• TIP-474: Tron Improvement Proposal for chain ID optimization
• Tron Developer Hub - Networks: Official network documentation
• Tron Developer Hub - eth_chainId: Chain ID RPC method documentation
• TronGrid Docs: Documentation for the TronGrid hosted node service
• ChainList: Tron chain listings
• TronGrid: Official Tron API service
• Tronscan: Tron blockchain explorer

Copyright

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Ignacio Rivera, Daniel Rocha, "namespaces/tron-caip2: Tron Namespace - Blockchain ID Specification [DRAFT]," Chain Agnostic Namespaces, tron-caip2, January 2026 / . [Online serial]. Available: https://github.com/ChainAgnostic/namespaces/tron-caip2.md