App to forward text messages?

Text forwarding is a solved problem on Android and impossible on iPhone. On Android you either install a forwarding app that reads SMS with your permission, or you use the carrier's own forwarding. There is no way to forward another person's messages from your own device.

Android options:

• SMS Forwarder (open source, free) — rules per sender, forwards to email, Telegram, another number or a webhook. The most flexible and the one I would use.
• Auto forward apps — same job, ads in the free tier, fewer rules.
• Tasker + AutoNotification — for people who like building it themselves.
• Google Messages for web — mirrors messages to a browser while the phone is on and connected; useful for your own phone, not someone else's.

iPhone: no app can forward SMS; Apple does not expose the store. The only built-in path is Text Message Forwarding to another Apple device signed into the same Apple ID (Settings → Messages → Text Message Forwarding).

The honest caveat: forwarding apps need SMS permission and run continuously, which is why they are also a malware delivery vector. Install from a known developer, and never grant SMS access to an app you cannot identify.

Where our app fits. Ultimate Phone Spy runs on Android 4.0+, Windows and macOS (features) and shows SMS threads in a dashboard rather than forwarding them to your phone. If you want a real-time copy in your inbox, SMS Forwarder plus our dashboard is the combination that works.