Beware implicit `Content-Type: "application/json"`

If you are sending a FormData body with fetch , things might not work correctly if you are (accidentally) setting the Content-Type request header to "application/json" . Problem I was sending a FormData object to a 3rd party API: const formData = new FormData ( ) formData . append ( 'foo' , someValue ) const response = await request ( 'https://example.com/api/' , { body : formData , method :…