Awesome Common Lisp

A curated list of awesome Common Lisp libraries.

All libraries listed here are available from [Quicklisp][16] unless stated otherwise. The ones marked with a ⭐ are so widespread and solid that they became community standards. You can't be wrong with them. This is the case for Quicklisp, BordeauxThreads and such. Libraries denoted with a 👍 are the ones we like and want to promote here at the Awesome-cl list. They proved solid, they may solve a problem better than a community standard but they aren't as widespread, or not considered as stable. For example, we prefer Spinneret over Cl-Who.

---

For a list of software, see the lisp-screenshots.org gallery and the awesome-cl-software list.

For examples of companies using CL in production, see lisp-lang.org's success stories, the awesome-lisp-companies list, but also LispWorks' success stories and Allegro's success stories.

---

Add something new! See the contributing section for adding something to the list.

This is released under the GNU Free Documentation License - its text is provided in the LICENSE file. Preference is given to [free software][13] and sellers who aren't evil for physical resources.

Table of Contents

• Artificial Intelligence (AI, LLMs)
  • Around the OpenAI API
  • MCP servers
  • Machine Learning
  • Natural Language Processing
  • Expert Systems
  • Educational
• Audio
• Build Systems
• Compilers, code generators
  • APL
  • C, C++
• Cryptography
• Cryptocurrencies
• Database
  • ORMs
  • Persistent object databases
  • Graph databases
  • Other DB wrappers
  • Migration tools
  • To third parties
  • Tools
• Data Formats
  • CSV
  • JSON
  • TOML
  • XML
  • YAML

Artificial Intelligence (AI, LLMs)

Around the OpenAI API

• openai-openapi-client - semi-automatically generated Openapi client updated frequently from the official Openapi specification. AGPL-3.
  • available on Ultralisp.
• cl-completions - LLM completions.
  • makes it easy to create GPT functions in Common Lisp.
  • Ollama support.
• cl-embeddings - LLM embeddings.
• cl-chroma - the vector DB interface.

demos: cl-rag-example and cl-chat, a LLM chat library and web UI.

Work In Progress:

• Caten - Deep Learning Compiler based on Polyhedral Compiler and Light-weight IRs, and Optimizing Pattern Matcher, written in Common Lisp

MCP servers

• cl-MCP - MCP for Common Lisp.
  • provides a newline‑delimited JSON‑RPC 2.0 transport over stdio or TCP, a small protocol layer (initialize, ping, tools/list, tools/call), and a REPL tool that evaluates forms and returns the last value.
• 40ants-MCP - a framework for building Model Context Protocol servers in Common Lisp.
• mcp-lisp - Common Lisp SDK for MCP (2025-11-25) with full conformance (44/44 checks) and limited A2A support. Supports stdio and SSE transports, tools, resources, prompts, structured errors, and access logging. [MIT][200].
• Lisply MCP - a generic Node.js wrapper meant to work with pretty much any language backend which can support "eval" and http .
  • By default, it comes configured to work with an existing reference-implementation backend CL-based container image which it will pull and run on-demand.
• cl-tron-mcp - MCP wrap around the Slime Swank library. Provides discoverable access to Swank commands, including control of the Swank debugging sessions and code hot-reload. Currently 90+ tools. Tested on SBCL and ECL.

Machine Learning

• MGL - a machine learning library for backpropagation neural networks, boltzmann machines, gaussian processes and more. [MIT][200].
  • some parts originally contributed by Ravenpack International.
  • used by its author to win the Higgs Boson Machine Learning Challenge.
  • more about the author: he also won the Google AI Challenge in 2010 using Common Lisp, but without MGL, as no machine learning was needed. A related talk (59', 2013).
• clml - originally developed by Mathematicl Systems Inc., a Japanese company. With a tutorial. [LLGPL][8].
• [antik](https://www.common-lisp.net/projec