# Custom transactions \[Call any writable function on any contract]

A custom transaction is a proposal built from arbitrary contract calls: use it for anything without a dedicated flow, like ERC-20 approvals, protocol interactions, or [enabling a module](/docs/accounts/modules#enabling-and-disabling). It can call any writable function on any contract deployed on a [supported network](/docs/introduction/networks-and-assets).

Open the builder with *Custom txn* on an account's page and paste the contract address, selecting the network if the contract exists on more than one.

* **Contract with a known ABI**: pick from the contract's writable functions and fill in its parameters. Payable functions add an *Amount to pay* input, denominated in ETH.
* **No ABI found**: enter raw calldata, with an optional ETH amount.

*Review* shows the decoded calls and a simulation before you submit. Like every [transaction](/docs/transactions), a custom transaction executes once signatures meet the account's threshold.

## Programmatic access

Via the [Splits CLI / MCP](/docs/introduction/agents):

* `splits transactions create custom --account 0x... --chainId 8453 --calls '[{"to":"0x...","data":"0x..."}]'`: propose 1–20 raw calls in one transaction, each with an optional `value` in wei (**Write** scope)