public interface CryptoAPI {
    @GET("v1/currencies/ticker?key=..........")
    Call<List<CryptoModel>> getData();
}

public class CryptoModel {

    @SerializedName("id")
    public String id;
    @SerializedName("currency")
    public String currency;
    @SerializedName("symbol")
    public String symbol;
    @SerializedName("name")
    public String name;
    @SerializedName("logo_url")
    public URL logo_url;
    @SerializedName("rank")
    public int rank;
    @SerializedName("price")
    public double price;
}