Gas fee token
Overview
When deploying a Buburuza Rollup chain, you can configure a custom ERC-20 token as the native gas token for that chain.
This allows transactions on your Buburuza network to use your own token (e.g., BUBU) instead of ETH for:
Paying transaction fees
Reimbursing the Batch Poster who posts compressed data to the parent chain (e.g., Ethereum or Arbitrum)
For example: A Buburuza Rollup chain could use BUBU as its native gas token while still paying ETH to post batches on Ethereum.
Why Use a Custom Gas Token?
Using a custom gas token gives chain owners more control over:
Token economics (using your project’s token for all gas fees)
User experience (users don’t need ETH to pay gas)
Brand integration (aligning fees with your ecosystem token)
However, it introduces additional configuration steps and exchange-rate dependencies, which must be handled carefully.
Requirements for the Custom Gas Token
The chosen ERC-20 token used as the native gas token must satisfy these conditions:
✅ Must be a standard ERC-20 token
✅ Transfers and approvals must occur directly via the token contract (no proxies or hooks)
❌ Must not be rebasing or include transfer fees
❌ Must not use transfer callbacks or revert if the sender and recipient are the same
Understanding the Fee Token Pricer
In Rollup mode, your Buburuza chain posts data to the parent chain (e.g., Ethereum).
The parent chain fee is paid in ETH.
The reimbursement for that cost is made in the child chain’s gas token (BUBU).
To calculate this reimbursement, the system needs a Fee Token Pricer — a smart contract that provides the exchange rate between:
The Fee Token Pricer ensures that the Batch Poster is reimbursed correctly in your gas token for the ETH they spent on L2.
Summary for Buburuza Chain
Goal
Use BUBU token as native gas token on Buburuza Rollup
Parent Chain
Ethereum or Arbitrum
Fee Token
BUBU (ERC-20)
Pricer Contract
Determines exchange rate between Arbitrum ETH ↔ BUBU
Deployment Tool
createERC20Rollup.ts
Key Benefit
Enables all gas fees and reimbursements in BUBU, maintaining ecosystem consistency
Last updated