Settlement Token Compatibility

This page documents settlement-token compatibility and the legacy MNEE_* aliases that Coal still accepts. Coal now describes settlement generically: USDC is the default fallback, and you can configure another Base token when needed.

Key Properties

Property	Value
Default asset	USDC on Base
Custom asset support	Any Base ERC-20 you explicitly configure
Decimals	Defaults to 6, but configurable
Network	Base
Selection model	Global settlement token per environment
Compatibility	Legacy `MNEE_*` env vars still supported

Default Behavior

If you do nothing, Coal uses USDC.
If you configure a custom settlement token address, Coal uses that token instead.
Most docs should describe the settlement asset generically unless the page is specifically about token compatibility.

	Custom token on Base	ETH	USDC
Settlement time	~2 seconds	~12 seconds	~2 seconds
Transfer fee	< $0.01	Variable (gas)	< $0.01
Price volatility	None (stable)	High	None
Configuration complexity	Higher	N/A	Lowest

How Coal Uses the Configured Settlement Token

When a customer pays via Coal:

Customer sends the configured settlement token from their wallet to the merchant's payout address on Base
Coal verifies the transfer on-chain (checks amount, recipient, Transfer event)
Merchant receives funds in their payout wallet, no intermediary

Coal is non-custodial — we never hold your funds.

Setting Your Payout Address

Your payout address is the Base-compatible wallet address where you want to receive payments. Set it in Console → Settings.

Double-check your address

Payments are irreversible. Verify your payout address before going live — if you enter the wrong address, Coal cannot recover the funds.

Compatible wallets: MetaMask, Coinbase Wallet, Rainbow, any wallet supporting Base (EVM-compatible).

Token Contract

The currently configured settlement token contract on Base:

text

10x...  (Base mainnet — see usecoal.xyz for current address)

You can verify any transaction on Basescan by searching the contract address.

Amount Formatting

Settlement amounts in Coal's API are strings to avoid floating-point precision errors:

json

1{ "amount": "49.99" }   // ✓ String — precise
2{ "amount": 49.99 }     // ✓ Also accepted for input

Always store and compare amounts as strings or integers in the smallest unit. Coal's backend uses BigInt arithmetic internally.

Choosing a Settlement Token

Use USDC if you want the cleanest default setup. Use a custom token only when you intentionally need a different settlement asset for product, treasury, or partner reasons.

	USDC	Custom token
Default	Yes	No
Configuration	None	Requires token address, decimals, symbol, and name
Network	Base	Base
Checkout display	Automatic	Uses your configured symbol and name
Legacy support	N/A	`MNEE_*` aliases still supported

To use USDC (default): leave SETTLEMENT_TOKEN_ADDRESS / NEXT_PUBLIC_SETTLEMENT_TOKEN_ADDRESS unset.

To use a custom token: set SETTLEMENT_TOKEN_ADDRESS, SETTLEMENT_TOKEN_DECIMALS, SETTLEMENT_TOKEN_SYMBOL, and SETTLEMENT_TOKEN_NAME in the backend, plus the matching NEXT_PUBLIC_... values in the frontend.

The switch is seamless — the checkout UI, verification flow, and webhook payloads all adapt to the configured settlement token.