Add README.md and LICENSE

README.md

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+A simple wrapper to save and restore [localStorage][0] of webapps in server
+
+A browser's localStorage allows webapps to store data locally in browser's
+cache. The data usually contains apps's state and credentials to access other
+resources. This wrapper periodically uploads the localStorage to the server and
+restores back to the browser on first load. This is useful for browsers that
+cleanup local storage when exiting like [Tor Browser][1] or to share across
+multiple browsers
+
+## How does it work?
+
+On path `/wrap/` of the webapp, [wrap.html](./wrap.html) is served. This
+contains the actual app in an `iframe`. Before the iframe would load,
+javascript fetches the localStorage from server and sets the browser
+localStorage. Then sets a timer for every 10 minutes to update back to server.
+
+Note:
+
+1. [localStorage][0] is accessible to only the same domain. So this only works
+   when you selfhost the webapp
+2. Make sure the webapp is properly authenticated without relying on
+   localStorage. E.g.
+
+   a. Setup HTTP Basic Auth
+   b. Webapp is only served inside home network
+   c. Served under a secret URL not shared with anyone like [tor onion url][3]
+
+
+## Usecase example
+
+[Phanpy][2] is web client to fediverse servers. Phanpy keeps the access token
+to the fediverse server in [localStorage][0]. This way the user can access
+their profile without having to login and authorize phanpy everytime.
+
+Below is my [Caddy][6] file config for phanpy.
+
+```Caddyfile
+http://phanpy.{$PRIVATE_ONION} {
+        header {
+            Content-Security-Policy "default-src 'self' 'unsafe-inline' social.balki.me wss://social.balki.me data: ;"
+            Referrer-Policy same-origin
+        }
+        reverse_proxy /wrap/* localhost:3242
+        root * /var/www/phanpy/
+        file_server
+}
+```
+
+Here the `PRIVATE_ONION` is secret and anyone who knows can accesss the
+fediverse profile. [CSP][5] header restricts which external sites are allowed
+in javascript. All of those need to be selfhosted as they receive the url in
+[Origin][7] header. [Referer-Policy][8] header makes sure not leak the url when
+clicking on external links.
+
+See [here][4] to learn how to setup an onion service.
+
+Let me know at `@balki@balki.me` in fediverse, if you find it useful
+
+## Install
+
+```bash
+go install go.balki.me/remote-local-storage@latest
+```
+
+## Links
+
+[0]: https://developer.mozilla.org/docs/Web/API/Window/localStorage
+[1]: https://torproject.org
+[2]: https://phanpy.social
+[3]: https://community.torproject.org/onion-services/
+[4]: https://community.torproject.org/onion-services/setup/
+[5]: https://developer.mozilla.org/en-US/docs/Web/HTTP/CSP
+[6]: https://caddyserver.com/
+[7]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Origin
+[8]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy