Create the order meta-data file

There's a tool part of CoW Protocol Explorer to assist in the process of defining a custom meta-data file. It's available at There you will be able to interactively build the file, upload it to IPFS and decode existing appData hashes.
Alternatively, you can also produce the file manualy. Create a text file document with the following content, where: version, appCode, metadata is mandatory environment and referrer are optional
For more details on the file format, go to the spec.
"version": "0.4.0",
"appCode": "YourAppCode",
"environment": "production",
"metadata": {
"referrer": {
"version": "0.1.0",
"referrer": "0x0000000000000000000000000000000000000000"