The direct successor for UI/UX design. It handles wireframing, prototyping, and collaboration much better than Fireworks ever could.
Most sites offering "free" serial numbers or "keygens" bundle their downloads with malware, ransomware, or spyware that can compromise your personal information.
If you have a legitimate, previously purchased license, you can sometimes find the installer in your Adobe account under "Order History," but Adobe generally recommends moving to modern alternatives [4]. Better Alternatives to Fireworks CS6