Question: I'm running into an issue with my isomorphic JavaScript app using React and Express. 

I am trying to make an HTTP request with axios.get when my component mounts

```
componentDidMount() {
  const url = 'http://ufc-data-api.ufc.com/api/v3/iphone/fighters/title_holders';
  axios.get(url).then( res => {
    //use res to update current state
  })
}

```

I am getting a status 200 res from the API, but I am not getting any response data and getting an error in my console

```
XMLHttpRequest cannot load http://ufc-data-api.ufc.com/api/v3/iphone/fighters/title_holders. 
No 'Access-Control-Allow-Origin' header is present on the requested resource. 
Origin 'http://localhost:3000' is therefore not allowed access.

```

However, if I make the request in my server.js

```
const url = 'http://ufc-data-api.ufc.com/api/v3/iphone/fighters/title_holders';
axios.get(url).then(res => {
    //console.log(res);
});

```

It works fine and I get response data when the server starts. Is this an issue with the actual API or am I doing something wrong? If this was a CORS issue I'm guessing the request in server.js wouldn't work either? Thanks!

Answer: 
CORS is a **browser** feature. Servers need to opt into CORS to allow browsers to bypass same-origin policy. Your server would not have that same restriction and be able to make requests to any server with a public API. <https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS>

Create an endpoint on your server with CORS enabled that can act as a proxy for your web app.
I don't know if this will help but I was getting the same error when remote debugging a react-native application. I was running the debugger on **192.168.x.x:8081**. I read a little bit on this [Cross-Origin Resource Sharing (CORS)](https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS/ "MDN link") to educate myself on what CORS is. (I'm a beginner) and changed my URL from **IP:8081** to **localhost:8081** and my issue was resolved.