Here is the reality check. The Japan Foundation does not officially release the Koushiki Mondaishuu as a free PDF. The physical book is copyrighted.
Most websites claiming to offer a "jlpt koushiki mondaishuu n4 pdf download" fall into one of three categories:
Warning: Downloading copyrighted PDFs from unofficial sources is illegal in most countries and violates the terms of service of the JLPT organizers. jlpt koushiki mondaishuu n4 pdf
Official Answer Sheet & Answers
The PDF includes a printable answer sheet and detailed correct answers (no lengthy explanations, though – just the answers).
Portable & Searchable
The PDF version is easy to carry on a tablet or laptop. You can search for specific question types or keywords, which isn’t possible with the physical book. Here is the reality check
Low Cost (or Free)
While the physical book costs ~¥1,400, the PDF is often available legally via library services or purchased at a lower price from Japanese e-book stores. Some learners share scanned copies – but beware of copyright issues.
Learners believe that because these are "official" questions, they might appear verbatim on their upcoming test. (Spoiler: They won't, but the format will be identical.) Official Answer Sheet & Answers The PDF includes