Seppuku FX is a small builder of experimental guitar effects and Eurorack modules based in Melbourne, Australia, run by a maker named Rhys. The shop is known for low-fi, circuit-bent and lo-fi-flavored designs that lean into noise, instability, and degraded textures rather than clean utility effects.

The catalog has included pedals like the Kompakt Kaset (a delay/modulation unit that emulates warped cassette playback), Memory Loss, the Mind Warp vibrato/chorus, the Repeater (inspired by the repeat-percussion circuit found in 1960s Vox Teardrop guitars and organs), the Octave Drone, and the IC Water. On the synthesizer side, Seppuku FX has produced Eurorack modules including a noise-oriented VCO. The maker has also released work under the related name Audioslime.

Seppuku's reputation in the boutique-pedal community sits alongside other niche, hand-built Australian builders, with units typically produced in small batches and frequently appearing on the secondhand market through Reverb listings.

Seppuku has 2 products cataloged on Equipboard, including Harmonizer & Octave Effects Pedals and Guitar Synth Pedals. Their gear is featured by 2 artists, with the strongest followings in Rock, Metal, and Electronic. Notable users include Keiji Haino and Futoshi Uehara.