The params field is used to provide form fields for the API. Here is a doc that helps to explain to it: API Docs | Transloadit
Regarding your code, the params field is placed in the “-d” section. The Content-Type header has to be removed otherwise it causes the HTTP request to fail. Here is a working example that shows how to use the params field:
curl -XPOST -d ‘params={
“auth”: {
“key”: “*************”
},
“steps”: {
“imported”: {
“robot”: “/http/import”,
“url”: “url.pic”
},
“watermark”: {
“robot”: “/image/resize”,
“use”: “imported”,
“watermark_url”: “url.pic”,
“watermark_size”: “25%”,
“watermark_position”:“bottom-right”,
“imagemagick_stack”:“v2.0.7”
}
}
}’ ‘https://api2.transloadit.com/assemblies’