Jobs · 04

Agent frameworks

The harness around a model

Use this when you are putting an agent inside your own product. Libraries and SDKs for tools, workflows, and multi-step runs — not a finished coding assistant.

Initial editorial estimate. Not a measured benchmark. Edit scores in data/tools.json.

1. 01

   Vercel AI SDK

   Best for Streaming AI features in a TypeScript web app

   TypeScript toolkit for streaming, tool calls, and chat UI.

   • + Open source and free
   • + The React hooks match how the rest of the app is built

   • − Long-running multi-agent systems will want a thicker framework
   • − You still pick and pay a model provider

   8.5

   Free

2. 02

   Mastra

   Best for TypeScript agents you keep in your repo

   TypeScript framework for agents, workflows, and evals.

   • + TypeScript-native, which matches most indie web stacks
   • + Open source

   • − Another framework to learn if the AI SDK already covers the feature
   • − Hosted pieces, if you use them: check site

   8.0

   Free

3. 03

   CrewAI

   Best for Role-based multi-agent prototypes in Python

   Multi-agent crews: roles, tasks, and a Python API.

   • + The role-and-task model is easy to explain
   • + The core library is open source

   • − Multi-agent setups multiply cost and failure modes
   • − Hosted platform pricing: check site

   7.7

   Free

4. 04

   Pydantic AI

   Best for Typed Python agents

   Python agent framework from the Pydantic team, typed end to end.

   • + Open source
   • + Types are the point, which keeps tool I/O honest

   • − Python-only, so it is the wrong pick for a Next.js UI
   • − You still design the tools and pay for the model

   7.6

   Free

5. 05

   LangGraph

   Best for Agents that are workflows, not a single loop

   Graph-shaped agents with state, from the LangChain team.

   • + Open source
   • + State and control flow are explicit

   • − More machinery than a weekend chat endpoint needs
   • − You still bring a model and an opinion about the graph

   7.3

   Free

6. 06

   LlamaIndex

   Best for Retrieval over your own documents

   A data framework for connecting documents and models.

   • + Open source
   • + The data and index layer is the focus, and it shows

   • − Easy to overbuild a vector index for a problem search would solve
   • − Hosted LlamaCloud pricing, if you use it: check site

   7.0

   Free

7. 07

   LangChain

   Best for A general LLM app framework with a huge ecosystem

   The original LLM application framework, plus a hosted LangSmith side.

   • + The library is open source
   • + Docs, integrations, and examples are everywhere

   • − The abstraction surface is large for a weekend agent
   • − Hosted LangSmith pricing, if you use it: check site

   6.7

   Free