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Langroid: Harness LLMs with Multi-Agent Programming

The LLM Opportunity

Given the remarkable abilities of recent Large Language Models (LLMs), there is an unprecedented opportunity to build intelligent applications powered by this transformative technology. The top question for any enterprise is: how best to harness the power of LLMs for complex applications? For technical and practical reasons, building LLM-powered applications is not as simple as throwing a task at an LLM-system and expecting it to do it.

Langroid's Multi-Agent Programming Framework

Effectively leveraging LLMs at scale requires a principled programming framework. In particular, there is often a need to maintain multiple LLM conversations, each instructed in different ways, and "responsible" for different aspects of a task.

An agent is a convenient abstraction that encapsulates LLM conversation state, along with access to long-term memory (vector-stores) and tools (a.k.a functions or plugins). Thus a Multi-Agent Programming framework is a natural fit for complex LLM-based applications.

Langroid is the first Python LLM-application framework that was explicitly designed with Agents as first-class citizens, and Multi-Agent Programming as the core design principle. The framework is inspired by ideas from the Actor Framework.

Langroid allows an intuitive definition of agents, tasks and task-delegation among agents. There is a principled mechanism to orchestrate multi-agent collaboration. Agents act as message-transformers, and take turns responding to (and transforming) the current message. The architecture is lightweight, transparent, flexible, and allows other types of orchestration to be implemented. Besides Agents, Langroid also provides simple ways to directly interact with
LLMs and vector-stores.


  • Agents as first-class citizens: The Agent class encapsulates LLM conversation state, and optionally a vector-store and tools. Agents are a core abstraction in Langroid; Agents act as message transformers, and by default provide 3 responder methods, one corresponding to each entity: LLM, Agent, User.
  • Tasks: A Task class wraps an Agent, gives the agent instructions (or roles, or goals), manages iteration over an Agent's responder methods, and orchestrates multi-agent interactions via hierarchical, recursive task-delegation. The method has the same type-signature as an Agent's responder's methods, and this is key to how a task of an agent can delegate to other sub-tasks: from the point of view of a Task, sub-tasks are simply additional responders, to be used in a round-robin fashion after the agent's own responders.
  • Modularity, Reusabilily, Loose coupling: The Agent and Task abstractions allow users to design Agents with specific skills, wrap them in Tasks, and combine tasks in a flexible way.
  • LLM Support: Langroid supports OpenAI LLMs including GPT-3.5-Turbo, GPT-4.
  • Caching of LLM prompts, responses: Langroid by default uses Redis for caching. Caching with Momento is also supported.
  • Vector-stores: Qdrant and Chroma are currently supported. Vector stores allow for Retrieval-Augmented-Generaation (RAG).
  • Grounding and source-citation: Access to external documents via vector-stores allows for grounding and source-citation.
  • Observability, Logging, Lineage: Langroid generates detailed logs of multi-agent interactions and maintains provenance/lineage of messages, so that you can trace back the origin of a message.
  • Tools/Plugins/Function-calling: Langroid supports OpenAI's recently released function calling feature. In addition, Langroid has its own native equivalent, which we call tools (also known as "plugins" in other contexts). Function calling and tools have the same developer-facing interface, implemented using Pydantic, which makes it very easy to define tools/functions and enable agents to use them. Benefits of using Pydantic are that you never have to write complex JSON specs for function calling, and when the LLM hallucinates malformed JSON, the Pydantic error message is sent back to the LLM so it can fix it!

Don't worry if some of these terms are not clear to you. The Getting Started Guide and subsequent pages will help you get up to speed.