Factor

Name: Factor
Author: The Factor contributors

A concatenative, stack-based programming language with a compiled implementation and interactive development environment.

Open source (BSD-2-Clause)By The Factor contributors

Free Open sourceWindows macOS Linux

Official websitefactorcode.org

Download pagedownloads.factorcode.org

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Read the Factor documentation

View the Factor source code

2 more ways to get Factor

Chocolateychoco install factor
Homebrewbrew install --cask factor

Alternatives

JA high-level array programming language suited to mathematical, statistical and logical analysis of data.
LuaA lightweight, embeddable scripting language with a small standalone interpreter.
PharoPharo offers a similar live, image-based development environment, but uses a Smalltalk-inspired object-oriented language instead of a concatenative stack-based one, under the MIT licence.
SqueakSqueak provides a live Smalltalk environment with the Morphic graphical framework, replacing concatenative code with an object-oriented image-based workflow and educational tools.
JanetJanet is a small Lisp-like language under 1MB that embeds easily in C programs, trading Factor's stack-based style for familiar functional and imperative code.
RacketRacket swaps stack-based code for a Lisp and Scheme style language with macros, a GUI framework and gradual typing, backed by extensive documentation and a package system.

See all alternatives

About Factor

Factor is a stack-based, concatenative programming language with dynamic types, extensible syntax, macros and garbage collection. The implementation compiles code for performance while keeping interactive development, and it comes with a large standard library and extensive documentation.

Programs are portable across common platforms, and Factor can deploy stand-alone applications. Binary packages for Windows, macOS and Linux are the recommended way to start, and nightly development builds are published alongside the stable release.

Strengths

Compiled implementation with interactive development
Extensive documentation and a full standard library
Deploys stand-alone applications
Frequent development builds

Limitations

Stack-based style takes time to learn
Small community compared with mainstream languages
Stable releases are infrequent

Details

Pricing: FreeFree and open source under the BSD 2-Clause licence.
License: BSD-2-Clause
Developer: The Factor contributors
Platforms: Windows, macOS, Linux
How it runs: Downloadable app
Account: Not required
Works offline: Yes
Best suited for: Programmers curious about concatenative languages who want a practical, documented system
Categories: Developer tools
Last verified: October 2, 2026
Added: October 2, 2026
Sources: factorcode.org
github.com/factor/factor

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