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AI for tool use

Function calling and tool-using LLMs.

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1LangChain

Open-source LLM application framework — chains, agents, RAG, and 700+ integrations with 127K GitHub stars

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2Vercel AI SDK

TypeScript AI SDK for React and Node — streaming, tool use, and multi-provider LLM integration with 1M+ npm downloads/week

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3LiteLLM

Python SDK and proxy to call 100+ LLMs with one interface

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4Instructor

Structured LLM outputs with Pydantic — type-safe data extraction from any language model

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5OpenAI Assistants API

Build persistent AI assistants with memory, tools, and file knowledge — no session management needed

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6Anthropic Python SDK

Official Python library for Claude API — access Claude Sonnet 4.6, Haiku 4.5, and Opus 4.6

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7AWS Bedrock

Fully managed foundation model service on AWS — Claude, Llama, Titan, and more

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