want to sent plain json as post request, with retrofit and moshi converter ??? {"id":1,"firstName":"Lokesh","lastName":"Gupta","roles":["ADMIN","MANAGER"]} Retrofit.Builder() .client(client) .baseUrl(baseUrl) .addConverterFactory(ScalarsConverterFactory.create()) // you need to add this for sending plain json object .addConverterFactory(MoshiConverterFactory.create(moshi)) .addCallAdapterFactory(RxJava2CallAdapterFactory.create()) .build()