Kasleder Fx is a boutique guitar and bass effects pedal maker based in Hungary, founded by electrical engineer Albert Kasléder. Kasléder built his first pedal — a Tube Screamer–style overdrive called Dirty Little Thing — in 2006, and went on to design roughly thirty different circuits before partnering with German guitar manufacturer Höfner from 2014 to 2019 to develop their boutique effects line. After that partnership ended, the workshop refocused entirely on the Kasleder Fx brand, with Eszter Budavári handling the hand-drawn graphic artwork that appears on each enclosure.

The lineup covers a range of drive flavors and a few specialty circuits, including the Toxic Twins dual overdrive, the Sweet Little Thing Tube Screamer–style overdrive, the Pelion Klon-inspired transparent overdrive, the Vintage King and GE Vintage King germanium fuzzes, The Toad treble booster/fuzz, the Pipergate booster/fuzz, the Mean Bone distortion, the Pressure Drop optical compressor, and the Time Trap analog delay. Bass players are served by the JellyFish overdrive and the Freaky Stone preamp/overdrive/fuzz.

Pedals are built in small batches using NOS and premium components, and are distributed internationally through retailers such as Thomann, Reverb, and Guitar Center alongside direct sales.

Kasleder has 12 products cataloged on Equipboard, including Fuzz Effects Pedals, Overdrive Effects Pedals, and Bass Effects Pedals. Their gear is featured by 1 artist, with the strongest followings in Rock, Pop, and Blues. Notable users include Tátrai Tibor.