Question: I am creating an API with our API server script and am trying to communicate with the API on the IONIC framework application. I am working but it keeps on bringing up the cross-origin blocked error: 

[![enter image description here](https://i.stack.imgur.com/x1jg4.png)](https://i.stack.imgur.com/x1jg4.png)

Answer: 
When developing locally using `ionic serve` or `ionic run/emulate -l -c` with livereload enabled, ionic creates a local dev server at port 8100 by default (`http://localhost:8100/` ). The `origin` in this case is `localhost:8100` , which when you contact an external service via HTTP with CORS enabled, they deem the request not trustworthy and therefor reject it.

As suggested by Ionic themselves (<http://blog.ionic.io/handling-cors-issues-in-ionic/>) , you can create a proxy alias within the Ionic app to route the API calls via, avoiding the `origin` issue altogether, however, their guide was specific for Ionic 1, so here is an update for Ionic v2. 

**Creating a Proxy in Ionic v2**
--------------------------------

Open `ionic.config.json` and add in the following `proxies` setup. 

```
{
  "name": "project-name",
  "app_id": "xyz-projectid",
  "v2": true,
  "typescript": true,
  "proxies": [{
    "path": "/api",
    "proxyUrl": "https://the-real-api-host.com"
  }]
}

```

In this instance, we are creating a path within the ionic app at `/api` ,which will forward requests to the endpoint `https://the-real-api-host.com` .
If you wanted to use a different api endpoint, for example `http://my-custom-api.com/api/v2/` , you could insert it into `proxyUrl` instead.

Updating References to API Endpoint
-----------------------------------

In your app code, you now need to update all the references of the base URL for the API endpoint at `https://the-real-api-host.com` with `/api` . A call to `/api` should be detected when in Ionic serve, and proxied to the real address.

Each projects implementation may vary. In my case, I did not have control of the API, as it was an external service, so I could not control the CORS handling/responses myself.

**Note:** remember to restart the server (`ionic serve`) or you will get 404's from your API call because it will not yet be proxying.
Cors error can only be resolved from server side.
But yes for browser only we can resolved it by installing cors extension but for device can be only from server side