Olsen Interface is a small builder of guitar effects pedals based in Omak, Washington. The shop operates as a boutique, hand-built operation, selling primarily through its Reverb storefront and accepting custom orders directly. Its catalog leans toward fuzz and distortion circuits with unusually dense control sets — multiple knobs, toggle switches, and momentary footswitches that push pedals well past single-purpose stompbox conventions.

Known models include the Warspit Distortion, a multi-stage distortion with seven knobs, five switches, and two footswitches; the MudWedge Fuzz, which pairs two fuzz controls with a separate noise control for deep, sludgy tones that hold up well with drop-tuned guitars; the Boss Frog Fuzz; and the Instant Fuzz. The brand's reputation centers on experimental, knob-heavy designs that reward extended tweaking rather than instant presets, and pedals are typically sold in small batches through Reverb.

Olsen Interface has 2 products cataloged on Equipboard, including Fuzz Effects Pedals and Distortion Effects Pedals.