I had got the same CORS error while working on a Vue.js project. You can resolve this either by building a proxy server or another way would be to disable the security settings of your browser (eg, CHROME) for accessing cross origin apis (this is temporary solution & not the best way to solve the issue). Both these solutions had worked for me. The later solution does not require any mock server or a proxy server to be build. Both these solutions can be resolved at the front end.
You can disable the chrome security settings for accessing apis out of the origin by typing the below command on the terminal:
/Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --user-data-dir="/tmp/chrome_dev_session" --disable-web-security
After running the above command on your terminal, a new chrome window with security settings disabled will open up. Now, run your program (npm run serve / npm run dev) again and this time you will not get any CORS error and would be able to GET request using axios.
Hope this helps!