Spantop turns Macs into second monitors

Hot take: this is a strong utility launch with an instantly understandable promise, but it wins only if the experience feels close to a native second display in real-world use.

• –The positioning is clear and practical: turn an existing Mac into a second monitor, no extra hardware required.
• –The audience is obvious and well-targeted: mobile workers, multi-device setups, and Mac users who want a temporary second screen.
• –The differentiator is the “real extended desktop” angle, which matters more than generic screen sharing or mirroring.
• –The biggest product risk is trust: claims like “0 latency” will be judged harshly if the app feels anything less than native.