Spitfire products are available on Splice. You can rent the Solo Violin for approximately $10/month. After 12-20 months, you own it. The first month is often $0. That is the closest legal thing to a free exclusive download.
Note: There is no official free full “Spitfire Solo Violin” Kontakt library from Spitfire Audio; this post imagines a compelling, ethical scenario and explains how composers can legally get high‑quality solo violin sounds without piracy. spitfire solo violin kontakt free exclusive download
If you are desperate for a premium solo violin sound right now and have zero budget, do not download cracks. Download these FREE Kontakt libraries instead. They require the full retail version of Kontakt (not the free Player). Spitfire products are available on Splice
While you cannot get the paid Solo Violin for free, Spitfire Audio offers an entirely separate, free range of instruments called Spitfire LABS. This is the closest you will get to an official "free exclusive download" for Kontakt (although LABS now runs on its own free plugin). Is it exclusive
What you get for free:
Is it exclusive? Yes. LABS instruments are not available anywhere else. They are time-limited collaborations that sometimes vanish from the store, so grabbing the Solo Violin while it is active is an "exclusive" experience.