The Queen Mum of Weblog Hosting Systems – written in server-side JavaScript since 2001.

Helma web framework

An interpreter for the Piet programming language

Visual Studio Code extension providing support for syntax coloring of Helma skins etc.

an interpreter for the programming language piet written in haskell

Sybleq Interpreter

Funge-98 interpreter and debugger written in Haskell

An implementation of the Malbolge interpreter in Rust.

Standard Interpreter for Malbolge, ported from Ben Olstead's original C interpreter.

Albus is a Whitespace interpreter written in Rust.

An Interpreter for the esoteric programming language Piet in Rust

LOLCODE language specification archives and development.

An interpreter with syscalls for the piet programming language.

This is an interpreter of the Unlambda language, written in the pure, lazy, functional language Haskell.

Ruby, Python, and Haskell interpreters for the Piet language

The canonical Whitespace interpreter written in Haskell, modified for modern compilers

Malbolge virtual machine and interpreter.

a tiny whitespace interpreter/virtual machine in rust - executes some 809.7 million whitespace instructions per second* - I am tempted to declare this the fastest VM for whitespace in the world, but I cannot be sure :)