how can i get the dropdown list with API

You can fetch that by api /<module>/enum/:field.

Regards

You can fetch that by api /<module>/enum/:field.

Regards

Thanks! It works.

Andre, you helped me out with this answer.

It is worth noting that this also works for relationship fields like contact_role on Opportunity Contacts.

Ex. 

GET rest/v11_12/Opportunities/enum/contact_role

{
  "": "",
  "Primary Decision Maker": "Primary Decision Maker",
  "Business Decision Maker": "Business Decision Maker",
  "Business Evaluator": "Business Evaluator",
  "Technical Decision Maker": "Technical Decision Maker",
  "Technical Evaluator": "Technical Evaluator",
  "Executive Sponsor": "Executive Sponsor",
  "Influencer": "Influencer",
  "Other": "Other"
}