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Best AI Skill Frameworks & LLM Libraries 2026

A curated ranking of 100 open-source developer frameworks and libraries for building production-ready LLM applications. Covers RAG pipelines, inference engines, fine-tuning toolkits, embeddings, and vector databases.

100 Skill Frameworks Listed
1.0M+ Total GitHub Stars
100% Open Source

Showing 100 skill frameworks sorted by GitHub stars — all open-source with proven community adoption.

#1
Transformers ★ 132k+ Featured

State-of-the-art ML models for NLP, vision and audio

llm framework huggingface open-source Apache-2.0
#2
LangChain ★ 93k+ Featured

Framework for building LLM-powered applications

llm framework rag open-source MIT
#3
Segment Anything ★ 46k+

Meta's promptable image segmentation foundation model

vision segmentation model open-source Apache-2.0
#4
vLLM ★ 38k+ Featured

High-throughput LLM serving with PagedAttention

llm inference serving open-source Apache-2.0
#5
LlamaIndex ★ 37k+ Featured

Data framework for LLM applications over custom data

rag framework llm open-source MIT
#6
LLaMA-Factory ★ 36k+

Unified fine-tuning framework for 100+ LLMs with WebUI

fine-tuning llm framework open-source Apache-2.0
#7
MarkItDown ★ 35k+

Microsoft utility to convert files and documents to Markdown

document parsing markdown microsoft MIT
#8
DeepSpeed ★ 35k+

Microsoft's deep learning optimization library for scale

training distributed performance microsoft Apache-2.0
#9
Gradio ★ 33k+ Featured

Build web demos and UIs for ML models in Python

ui framework demo open-source Apache-2.0
#10
Ray ★ 32k+

Unified framework for scaling AI and Python applications

distributed scaling framework open-source
#11
Faiss ★ 31k+

Facebook's library for efficient similarity search and clustering

vector-search embeddings facebook open-source
#12
Milvus ★ 29k+

Open-source vector database for scalable similarity search

vector-db embeddings open-source cloud-native
#13
spaCy ★ 29k+

Industrial-strength natural language processing library

nlp framework production open-source
#14
PyTorch Lightning ★ 27k+

Deep learning framework to train, deploy and ship AI products

training pytorch framework open-source
#15
Diffusers (HF) ★ 26k+

HuggingFace library for diffusion model development

diffusion framework image open-source
#16
CLIP ★ 23k+

OpenAI's contrastive language-image pretraining model

vision embedding multimodal open-source
#17
Semantic Kernel ★ 23k+

Microsoft SDK integrating LLMs into applications

framework llm sdk microsoft
#18
OpenAI Python SDK ★ 23k+

Official OpenAI Python client library

sdk openai api open-source
#19
Unsloth ★ 22k+

2-5x faster LLM fine-tuning with 70% less memory

fine-tuning performance llm open-source
#20
Mem0 ★ 22k+

Memory layer for AI agents and assistants

memory framework llm open-source
#21
Qdrant ★ 21k+

High-performance vector similarity search engine

vector-db embeddings rust open-source
#22
Label Studio ★ 20k+

Multi-type data labeling tool for ML training data

labeling data annotation open-source
#23
HF Datasets ★ 19k+

HuggingFace library for easy ML dataset loading and sharing

datasets ml huggingface open-source
#24
DSPy ★ 19k+

Programming—not prompting—language models

prompt framework llm open-source
#25
Guidance ★ 19k+

Efficient control and templating for language models

prompt framework llm open-source
#26
MLflow ★ 18k+

Platform for ML lifecycle: tracking, registry, deployment

mlops tracking deployment open-source
#27
GraphRAG ★ 18k+

Microsoft's graph-based RAG for complex reasoning over text

rag knowledge-graph microsoft open-source
#28
Haystack ★ 17k+

End-to-end NLP framework for search and QA systems

rag nlp framework open-source
#29
MLX Framework ★ 17k+

Apple's array framework for ML on Apple Silicon

framework apple-silicon training open-source
#30
PEFT ★ 16k+

Parameter-efficient fine-tuning methods including LoRA

fine-tuning lora llm open-source
#31
Gensim ★ 16k+

Topic modelling and document similarity library

nlp topic-modeling embeddings open-source
#32
Chroma ★ 15k+

Open-source AI-native vector database

vector-db embeddings rag open-source
#33
Sentence Transformers ★ 14k+

Multilingual sentence, paragraph and image embeddings

embeddings nlp search open-source
#34
LiteLLM ★ 14k+

Unified API for 100+ LLMs with OpenAI format

llm api framework open-source
#35
ONNX Runtime ★ 13k+

Cross-platform ML inferencing accelerator by Microsoft

inference cross-platform performance microsoft
#36
pgvector ★ 13k+

Open-source vector similarity search for PostgreSQL

vector-db postgresql embeddings open-source
#37
DVC ★ 13k+

ML experiments and data version control system

mlops versioning data open-source
#38
Annoy ★ 13k+

Approximate nearest neighbors library by Spotify

vector-search approximate embeddings open-source
#39
NLTK ★ 13k+

Natural Language Toolkit - classic Python NLP library

nlp text-processing python open-source
#40
Docling ★ 12k+

IBM's document parsing and understanding library

document parsing ocr open-source
#41
Composio ★ 12k+

Integration platform for AI agents with 250+ tools

tools integration agents open-source
#42
PandasAI ★ 12k+

Chat with your data using natural language via LLMs

data sql analysis open-source
#43
Composio SDK ★ 12k+

SDK for integrating 250+ tools into AI agents and LLMs

sdk tools integration open-source
#44
Weaviate ★ 11k+

Open-source vector database with hybrid semantic search

vector-db hybrid-search open-source go
#45
GGML ★ 11k+

Tensor library for machine learning on edge devices

inference edge c open-source
#46
tiktoken ★ 11k+

Fast BPE tokenizer used by OpenAI models

tokenization openai nlp open-source
#47
TRL ★ 10k+

Train LLMs with RLHF, PPO, DPO and reward modeling

fine-tuning rlhf dpo open-source
#48
LitGPT ★ 10k+

Pre-train, finetune, and deploy 20+ LLMs on your hardware

training fine-tuning llm open-source
#49
OpenCLIP ★ 10k+

Open-source implementation of CLIP vision-language models

vision embedding multimodal open-source
#50
Outlines ★ 10k+

Structured text generation for language models

llm structured-output framework open-source
#51
Prompt Flow ★ 10k+

Build and evaluate LLM-based AI flows

prompt workflow llm microsoft
#52
LightRAG ★ 10k+

Simple and fast RAG system with knowledge graph support

rag knowledge-graph lightweight open-source
#53
Tokenizers ★ 9k+

Extremely fast tokenizers for modern NLP

nlp tokenization rust open-source
#54
Text Generation Inference ★ 9k+

Production LLM serving toolkit by HuggingFace

llm serving inference open-source
#55
OpenLLM ★ 9k+

Run LLMs in production with BentoML

serving llm production open-source
#56
Instructor ★ 9k+

Structured outputs for LLMs using Pydantic

llm framework structured-output open-source
#57
txtai ★ 9k+

All-in-one open-source embeddings database

embeddings search rag open-source
#58
Grounding DINO ★ 8k+

Open-set object detection with language grounding

vision detection grounding open-source
#59
FlagEmbedding ★ 8k+

Retrieval and embedding models including BGE series

embeddings retrieval rag open-source
#60
Axolotl ★ 8k+

Streamlined tool for easily fine-tuning AI models

fine-tuning llm flexible open-source
#61
Accelerate ★ 8k+

Training and inference PyTorch at scale with minimal code changes

training distributed pytorch open-source
#62
Unstructured ★ 8k+

Pre-processing library for unstructured data (PDFs, docs, etc.)

document parsing rag open-source
#63
Deep Lake ★ 8k+

Database for AI data with multimodal vector storage

vector-db multimodal storage open-source
#64
Cleanlab ★ 8k+

Data-centric AI library for finding and fixing dataset issues

data-quality mlops cleaning open-source
#65
llama-cpp-python ★ 8k+

Python bindings for llama.cpp with OpenAI-compatible API

llm python inference open-source
#66
Pydantic AI ★ 8k+

Type-safe AI agent framework built on Pydantic

framework type-safe agents open-source
#67
SGLang ★ 8k+

Fast serving framework for large language and vision models

llm serving structured open-source
#68
LLMWare ★ 8k+

Structured RAG framework for enterprise LLM applications

rag enterprise framework open-source
#69
Ragas ★ 7k+

Evaluation framework for RAG pipelines

rag evaluation testing open-source
#70
LangFuse ★ 7k+

Open-source LLM engineering platform for observability

observability tracing llm open-source
#71
BentoML ★ 7k+

Build, ship and run AI applications in the cloud

serving deployment framework open-source
#72
Optimum ★ 7k+

HuggingFace acceleration and optimization for inference

inference optimization huggingface open-source
#73
Chainlit ★ 7k+

Build production-ready conversational AI applications

chat framework ui open-source
#74
E2B ★ 7k+

Secure sandboxed environments for AI code execution

sandbox code-execution agents open-source
#75
LM Evaluation Harness ★ 7k+

Framework for evaluating language models on NLP tasks

evaluation benchmark llm open-source
#76
BitsAndBytes ★ 6k+

8-bit and 4-bit quantization for LLM memory efficiency

quantization llm memory open-source
#77
Marvin ★ 5k+

AI toolkit for building natural language interfaces

llm functions toolkit open-source
#78
DeepEval ★ 5k+

Unit testing framework for LLM outputs and RAG pipelines

evaluation testing rag open-source
#79
Evidently ★ 5k+

ML and LLM monitoring and evaluation platform

monitoring mlops evaluation open-source
#80
Promptfoo ★ 5k+

Test and evaluate LLM outputs and prompt quality

testing prompt evaluation open-source
#81
Marqo ★ 5k+

Tensor search engine for text and images

search multimodal vector-db open-source
#82
Vespa ★ 5k+

Open source AI search and recommendation engine

search vector-db recommendation open-source
#83
Guardrails AI ★ 4k+

Add validation and correction guardrails to LLM outputs

safety validation llm open-source
#84
NeMo Guardrails ★ 4k+

NVIDIA toolkit for adding programmable guardrails to LLMs

safety guardrails llm nvidia
#85
LanceDB ★ 4k+

Serverless vector database for AI applications

vector-db serverless embeddings open-source
#86
AutoGPTQ ★ 4k+

Easy GPTQ model quantization for LLM deployment

quantization llm deployment open-source
#87
Arize Phoenix ★ 4k+

AI observability platform for LLM tracing and evaluation

observability tracing evaluation open-source
#88
TorchTune ★ 4k+

PyTorch-native finetuning library for LLMs

fine-tuning pytorch llm open-source
#89
LMDeploy ★ 4k+

Efficient LLM compression, deployment and serving toolkit

deployment serving llm open-source
#90
CTransformers ★ 4k+

Python bindings for GGML/GGUF quantized models

inference quantization python open-source
#91
RAGatouille ★ 3k+

Use ColBERT and late-interaction models in RAG pipelines

rag retrieval colbert open-source
#92
LMQL ★ 3k+

Query language and runtime for large language models

llm query-language constrained open-source
#93
Anthropic SDK ★ 3k+

Official Python library for Anthropic's Claude API

sdk claude api open-source
#94
Text Embeddings Inference ★ 3k+

Blazing fast inference for text embeddings

embeddings inference serving open-source
#95
DocArray ★ 3k+

Dataclass for multimodal data representation in ML

multimodal data ml open-source
#96
Semantic Router ★ 2k+

Superfast AI decision-making and routing layer for LLMs

routing framework llm open-source
#97
TruLens ★ 2k+

Evaluation and tracking for LLM-based applications

evaluation tracing rag open-source
#98
Nitro ★ 2k+

Embedded AI inference library for desktop and edge

inference embedded local open-source
#99
PromptTools ★ 2k+

Open-source tools for testing and experimenting with prompts

testing prompt evaluation open-source
#100
LLM Guard ★ 1k+

Security toolkit for LLMs to detect prompt injection and PII

security safety llm open-source
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