Why would you want a webapp without a backend? The web was explicitly conceived for "user agents" to interact with "servers" and the web ecosystem has very litt

Why would you want a webapp without a backend? The web was explicitly conceived for "user agents" to interact with "servers" and the web ecosystem has very little benefits (and many downsides) outside of this use-case. If you're looking for cross-platform UI toolkits, you could take a look at Qt (for example) which easily produces static backendless (non-web)apps.