K-Line Guitars is a boutique electric guitar maker based in St. Louis, Missouri, founded by luthier Chris Kroenlein in the mid-1990s. Kroenlein, the son of an auto body shop owner, began building partscasters as a side project before transitioning to full-time guitar building. With no formal luthier training, he learned through trial and error, eventually bringing nearly 95% of production in-house — including bodies, necks, and hand-wound pickups. The company's lineup of vintage-inspired solidbody electrics includes the Springfield (S-style), Truxton (T-style), San Bernardino (J-style offset), Texola, and Del Mar, as well as a Jazz Bass-inspired bass model. K-Line also produces boutique pickups and amplifiers, including the Bevo, Manchester, and Parkmoor Reverb.

K-Line instruments are known for their nitrocellulose lacquer finishes, refined U-shaped neck profiles, and proprietary aging process that ranges from a "closet classic" look to a more heavily worn relic aesthetic. The brand debuted online through The Gear Page forum community and later gained wider visibility at the Winter NAMM Show. Players drawn to K-Line's blend of vintage aesthetics and modern playability include jazz guitarist John Scofield, Steve Miller, Devon Allman, Michael Glabicki of Rusted Root, Todd Park Mohr of Big Head Todd and the Monsters, Greg Martin of the Kentucky Head Hunters, Nashville session guitarist Guthrie Trapp, and blues artist Mike Zito.

K-Line has 3 products cataloged on Equipboard, including Solid Body Electric Guitars. Their gear is featured by 5 artists, with the strongest followings in Rock, Folk, World, & Country, and Blues. Notable users include Jake Ewald, Steve Miller, and John Nathan Cordy.