Exchange Integration

Overview

The objective of this document is to provide a brief overview of how to integrate with the EVM-Compatible Avalanche C-Chain.

For teams that already support ETH, supporting the C-Chain is as straightforward as spinning up an Avalanche node (which has the same API as go-ethereum) and populating Avalanche's ChainID (43114) when constructing transactions.

Additionally, Ava Labs maintains an implementation of the Rosetta API for the C-Chain called avalanche-rosetta. You can learn more about this standardized integration path on the attached Rosetta API website.

Integration Using EVM Endpoints

Running an Avalanche Node

If you want to build your node form source or include it in a docker image, reference the AvalancheGo GitHub repository. To quickly get up and running, you can use the node installation script that automates installing and updating AvalancheGo node as a systemd service on Linux, using prebuilt binaries.

Configuring an Avalanche Node

All configuration options and their default values are described here.

You can supply configuration options on the command line, or use a config file, which can be easier to work with when supplying many options. You can specify the config file location with --config-file=config.json, where config.json is a JSON file whose keys and values are option names and values.

Individual chains, including the C-Chain, have their own configuration options which are separate from the node-level options. These can also be specified in a config file. For more details, see here.

The C-Chain config file should be at $HOME/.avalanchego/configs/chains/C/config.json. You can also tell AvalancheGo to look somewhere else for the C-Chain config file with option --chain-config-dir. An example C-Chain config file:

{
  "local-txs-enabled": true,
  "pruning-enabled": false,
  "state-sync-enabled": false
}

Interacting with the C-Chain

Interacting with the C-Chain is identical to interacting with go-ethereum. You can find the reference material for C-Chain API here.

The C-Chain node does not serve the personal_ and admin_ namespaces, eth_accounts or eth_coinbase. The node holds no keys. Sign transactions in your own system and send them with eth_sendRawTransaction. By default, the node serves the web3, net, txpool, price, chain, tx, subscription, avalanche and trace API groups. To change the groups that the node serves, set apis in the C-Chain config file. Do not use eth-apis, which is deprecated.

Integration Using Rosetta

Rosetta is an open-source specification and set of tools that makes integrating with different blockchain networks easier by presenting the same set of APIs for every network. The Rosetta API is made up of 2 core components, the Data API and the Construction API.

Together, these APIs allow for anyone to read and write to blockchains in a standard format over a standard communication protocol. The specifications for these APIs can be found in the rosetta-specifications repository.

You can find the Rosetta server implementation for Avalanche C-Chain here, all you need to do is install and run the server with proper configuration. It comes with a Dockerfile that packages both the server and the Avalanche client. Detailed instructions can be found in the linked repository.

Constructing Transactions

Avalanche C-Chain transactions are standard EVM transactions, with these differences:

• Sign them with Avalanche's ChainID (43114).
• Use a legacy, EIP-2930 or EIP-1559 transaction. The C-Chain does not accept blob (EIP-4844) or set-code (EIP-7702) transactions.
• The C-Chain charges each transaction max(gasUsed, ceil(gasLimit / 2)) gas. Do not set a gas limit more than 2 times the expected gas use. A 21,000 gas AVAX transfer with a 21,000 gas limit is not affected.
• The mempool rejects a transaction whose gas limit is too small for its size, with the error insufficient gas limit for tx size. At a block gas limit of 80,000,000, a transaction needs about 51 gas per byte. AvalancheGo v1.15.1 and later include this minimum in eth_estimateGas.
• The detailed dynamic gas fee can be found here.

For development purposes, Avalanche supports all the popular tooling for Ethereum, so developers familiar with Ethereum and Solidity can feel right at home. Popular development environments include:

• Remix IDE
• thirdweb
• Hardhat

Ingesting On-Chain Data

You can use any standard way of ingesting on-chain data you use for Ethereum network.

Determining Finality

Avalanche consensus gives irreversible finality in about 1 second. A C-Chain transaction is final when consensus accepts its block. Snowman has no re-orgs, so you do not need to wait for more confirmations.

After acceptance, the node executes the block. Receipts, logs and the post-execution state exist only after execution:

• latest and eth_blockNumber return the last executed block. Read balances, state and logs at latest.
• eth_getBlockByNumber with an explicit number also returns accepted blocks that are not executed yet. A number above the last accepted block returns null.
• For a transaction in an accepted block, eth_getTransactionReceipt waits until the transaction executes. It returns null if the transaction is not in an accepted block.
• safe and finalized return the last settled block, a few blocks behind latest. These tags do not mark finality: every accepted block is already final.

(Optional) Custom Golang SDK

If you plan on extracting data from the C-Chain into your own systems using Golang, we recommend using our custom ethclient. The standard go-ethereum Ethereum client does not compute block hashes correctly (when you call block.Hash()) because it doesn't take into account the added ExtDataHash header field in Avalanche C-Chain blocks, which is used move AVAX between chains (X-Chain and P-Chain). You can read more about our multi-chain abstraction here (out of scope for a normal C-Chain integration).

If you plan on reading JSON responses directly or use web3.js (doesn't recompute hash received over the wire) to extract on-chain transaction data/logs/receipts, you shouldn't have any issues!

Support

If you have any problems or questions, reach out either directly to our developers, or on our public Discord server.