This server can handle upload images, resize to max allowed size and store on local filesystem. All images converted to jpg.

simple-image-server

curl \
  -F "file=@/path/to/image/image.jpg" \
  localhost:8080/upload

You will get receive result such as: {"url":"https://example.com/image.jpg"}, now you can access this url from browser.

/upload - send to it images as multipart or just slice of bytes. Result in json sample: {"url":"https://example.com/image.jpg"}