0x Limit Orders may be filled by calling the following methods on the Exchange Proxy. Our protocol utilization package is available for developers to generate, parse, sign and validate 0x orders.
These are the basic functions for filling a 0x Limit Order:
Python - Python 0x v4 RFQ Guide covers how to create, hash, sign, fill, get state, and cancel a 0x RFQ Order. Note that the code can be modified by making minor modifications, to also work for 0x Limit Orders.