These services are called CORS proxies! I recently made an updated list of the currently working free ones here: https://gist.github.com/reynaldichernando/eab9c4e31e30677f17...

Do note that these proxies are for testing only, and they are heavily rate limited.

For production use case, you might consider using Corsfix (https://corsfix.com)

(I am affiliated with Corsfix)