I am trying to send a get request to the Wikipedia API. I am sending the request form a angular frontend so i'm trying to use the Heroku CORS Anywhere endpoint to avoid CORS issues. For some reason, I'm still getting a 503 response saying no access-control-allow-origin header is present on the requested resource. Any idea why this would happen/what else I can try?

My code:

import { Injectable } from '@angular/core';

import { Http, Response, } from '@angular/http';

import { Observable } from 'rxjs/Rx';







@Injectable()

export class RestService {

    API_URL: string = 'https://cors-anywhere.herokuapp.com/https://en.wikipedia.org/wiki/';



  constructor(private http: Http) { }



  public getRandomArticle() : Observable<any> {

        return this.http.get(`${this.API_URL}Special:Random`)

        .map((res: Response) => res.json())

        .catch((err: any) => Observable.throw(err || 'server error'));

  }



}