litgpt

PythonApache-2.0★ 13.7k

LitGPT provides from-scratch implementations of 20+ LLMs with recipes to pretrain, finetune, and deploy at scale, plus a Python API for loading

Framework

Install: pip install 'litgpt[extra]'

From the project's README

GitHub ↗

Written by the project's own authors, not by runchr. Snapshot taken 2026-10-29.

⚡ LitGPT

20+ high-performance LLMs with recipes to pretrain, finetune, and deploy at scale.

✅ From scratch implementations      ✅ No abstractions         ✅ Beginner friendly
   ✅ Flash attention                   ✅ FSDP                    ✅ LoRA, QLoRA, Adapter
✅ Reduce GPU memory (fp4/8/16/32)   ✅ 1-1000+ GPUs/TPUs       ✅ 20+ LLMs

Quick start • Models • Finetune • Deploy • All workflows • Features • Recipes (YAML) • Lightning AI • Tutorials

Looking for GPUs?

Over 340,000 developers use Lightning Cloud - purpose-built for PyTorch and PyTorch Lightning.

GPUs from $0.19.
Clusters: frontier-grade training/inference clusters.
AI Studio (vibe train): workspaces where AI helps you debug, tune and vibe train.
AI Studio (vibe deploy): workspaces where AI helps you optimize, and deploy models.
Notebooks: Persistent GPU workspaces where AI helps you code and analyze.
Inference: Deploy models as inference APIs.

Finetune, pretrain, and inference LLMs Lightning fast ⚡⚡

Every LLM is implemented from scratch with no abstractions and full control, making them blazing fast, minimal, and performant at enterprise scale.

✅ Enterprise ready - Apache 2.0 for unlimited enterprise use.
✅ Developer friendly - Easy debugging with no abstraction layers and single file implementations.
✅ Optimized performance - Models designed to maximize performance, reduce costs, and speed up training.
✅ Proven recipes - Highly-optimized training/finetuning recipes tested at enterprise scale.

Quick start

Install LitGPT

pip install 'litgpt[extra]'

Load and use any of the 20+ LLMs:

from litgpt import LLM

llm = LLM.load("microsoft/phi-2")
text = llm.generate("Fix the spelling: Every fall, the family goes to the mountains.")
print(text)
# Corrected Sentence: Every fall, the family goes to the mountains.

✅ Optimized for fast inference
✅ Quantization
✅ Runs on low-memory GPUs
✅ No layers of internal abstractions
✅ Optimized for production scale

Advanced install options

Install from source:

git clone https://github.com/Lightning-AI/litgpt
cd litgpt
# if using uv
uv sync --all-extras
# if using pip
pip install -e ".[extra,compiler,test]"

Explore the full Python API docs.

Choose from 20+ LLMs

Every model is written from scratch to maximize performance and remove layers of abstraction:

Model	Model size	Author	Reference
Llama 3, 3.1, 3.2, 3.3	1B, 3B, 8B, 70B, 405B	Meta AI	Meta AI 2024
Code Llama	7B, 13B, 34B, 70B	Meta AI	Rozière et al. 2023
CodeGemma	7B	Google	Google Team, Google Deepmind
Gemma 2	2B, 9B, 27B	Google	Google Team, Google Deepmind
Phi 4	14B	Microsoft Research	Abdin et al. 2024
Qwen2.5	0.5B, 1.5B, 3B, 7B, 14B, 32B, 72B	Alibaba Group	Qwen Team 2024
Qwen2.5 Coder	0.5B, 1.5B, 3B, 7B, 14B, 32B	Alibaba Group	Hui, Binyuan et al. 2024
R1 Distill Llama	8B, 70B	DeepSeek AI	DeepSeek AI 2025
...	...	...	...

See full list of 20+ LLMs

All models

Model	Model size	Author	Reference
CodeGemma	7B	Google	Google Team, Google Deepmind
Code Llama	7B, 13B, 34B, 70B	Meta AI	Rozière et al. 2023
Falcon	7B, 40B, 180B	TII UAE	TII 2023
Falcon 3	1B, 3B, 7B, 10B	TII UAE	TII 2024
FreeWilly2 (Stable Beluga 2)	70B	Stability AI	Stability AI 2023
Function Calling Llama 2	7B	Trelis	Trelis et al. 2023
Gemma	2B, 7B	Google	Google Team, Google Deepmind
Gemma 2	9B, 27B	Google	Google Team, Google Deepmind
Gemma 3	1B, 4B, 12B, 27B	Google	Google Team, Google Deepmind
Llama 2	7B, 13B, 70B	Meta AI	Touvron et al. 2023
Llama 3.1	8B, 70B	Meta AI	Meta AI 2024
Llama 3.2	1B, 3B	Meta AI	Meta AI 2024
Llama 3.3	70B	Meta AI	Meta AI 2024
Mathstral	7B	Mistral AI	Mistral AI 2024
MicroLlama	300M	Ken Wang	MicroLlama repo
Mixtral MoE	8x7B	Mistral AI	Mistral AI 2023
Mistral	7B, 123B	Mistral AI	Mistral AI 2023
Mixtral MoE	8x22B	Mistral AI	Mistral AI 2024
OLMo	1B, 7B	Allen Institute for AI (AI2)	Groeneveld et al. 2024
OpenLLaMA	3B, 7B, 13B	OpenLM Research	Geng & Liu 2023
Phi 1.5 & 2	1.3B, 2.7B	Microsoft Research	Li et al. 2023
Phi 3	3.8B	Microsoft Research	Abdin et al. 2024
Phi 4	14B	Microsoft Research	Abdin et al. 2024
Phi 4 Mini Instruct	3.8B	Microsoft Research	Microsoft 2025
Phi 4 Mini Reasoning	3.8B	Microsoft Research	Xu, Peng et al. 2025
Phi 4 Reasoning	3.8B	Microsoft Research	Abdin et al. 2025
Phi 4 Reasoning Plus	3.8B	Microsoft Research	Abdin et al. 2025
Platypus	7B, 13B, 70B	Lee et al.	Lee, Hunter, and Ruiz 2023
Pythia	{14,31,70,160,410}M, {1,1.4,2.8,6.9,12}B	EleutherAI	Biderman et al. 2023
Qwen2.5	0.5B, 1.5B, 3B, 7B, 14B, 32B, 72B	Alibaba Group	Qwen Team 2024
Qwen2.5 Coder	0.5B, 1.5B, 3B, 7B, 14B, 32B	Alibaba Group	Hui, Binyuan et al. 2024
Qwen2.5 1M (Long Context)	7B, 14B	Alibaba Group	Qwen Team 2025
Qwen2.5 Math	1.5B, 7B, 72B	Alibaba Group	An, Yang et al. 2024
QwQ	32B	Alibaba Group	Qwen Team 2025
QwQ-Preview	32B	Alibaba Group	Qwen Team 2024
Qwen3	0.6B, 1.7B, 4B{Hybrid, Thinking-2507, Instruct-2507}, 8B, 14B, 32B	Alibaba Group	Qwen Team 2025
Qwen3 MoE	30B{Hybrid, Thinking-2507, Instruct-2507}, 235B{Hybrid, Thinking-2507, Instruct-2507}	Alibaba Group	Qwen Team 2025
R1 Distill Llama	8B, 70B	DeepSeek AI	DeepSeek AI 2025
R1 Distill Qwen	1.5B, 7B, 14B, 32B	DeepSeek AI	DeepSeek AI 2025
SmolLM2	135M, 360M, 1.7B	Hugging Face	Hugging Face 2024
Salamandra	2B, 7B	Barcelona Supercomputing Centre	BSC-LTC 2024
StableCode	3B	Stability AI	Stability AI 2023
StableLM	3B, 7B	Stability AI	Stability AI 2023
StableLM Zephyr	3B	Stability AI	Stability AI 2023
TinyLlama	1.1B	Zhang et al.	Zhang et al. 2023

Tip: You can list all available models by running the litgpt download list command.

Workflows

Finetune • Pretrain • Continued pretraining • Evaluate • Deploy • Test

Use the command line interface to run advanced workflows such as pretraining or finetuning on your own data.

All workflows

After installing LitGPT, select the model and workflow to run (finetune, pretrain, evaluate, deploy, etc...):

# litgpt [action] [model]
litgpt  serve     meta-llama/Llama-3.2-3B-Instruct
litgpt  finetune  meta-llama/Llama-3.2-3B-Instruct
litgpt  pretrain  meta-llama/Llama-3.2-3B-Instruct
litgpt  chat      meta-llama/Llama-3.2-3B-Instruct
litgpt  evaluate  meta-llama/Llama-3.2-3B-Instruct

Finetune an LLM

Finetuning is the process of taking a pretrained AI model and further training it on a smaller, specialized dataset tailored to a specific task or application.

# 0) setup your dataset
curl -L https://huggingface.co/datasets/ksaw008/finance_alpaca/resolve/main/finance_alpaca.json -o my_custom_dataset.json

# 1) Finetune a model (auto downloads weights)
litgpt finetune microsoft/phi-2 \
  --data JSON \
  --data.json_path my_custom_dataset.json \
  --data.val_split_fraction 0.1 \
  --out_dir out/custom-model

# 2) Test the model
litgpt chat out/custom-model/final

# 3) Deploy the model
litgpt serve out/custom-model/final

Read the full finetuning docs

Deploy an LLM

Deploy a pretrained or finetuned LLM to use it in real-world applications. Deploy automatically sets up a web server that can be accessed by a website or app.

# deploy an out-of-the-box LLM
litgpt serve microsoft/phi-2

# deploy your own trained model
litgpt serve path/to/microsoft/phi-2/checkpoint

Show code to query server:

Test the server in a separate terminal and integrate the model API into your AI product:

# 3) Use the server (in a separate Python session)
import requests, json
response = requests.post(
    "http://127.0.0.1:8000/predict",
    json={"prompt": "Fix typos in the following sentence: Example input"}
)
print(response.json()["output"])

Read the full deploy docs.

Evaluate an LLM

Evaluate an LLM to test its performance on various tasks to see how well it understands and generates text. Simply put, we can evaluate things like how well it would do in college-level chemistry, coding, etc... (MMLU, Truthful QA, etc...)

litgpt evaluate microsoft/phi-2 --tasks 'truthfulqa_mc2,mmlu'

Read the full evaluation docs.

Test an LLM

Test how well the model works via an interactive chat. Use the chat command to chat, extract embeddings, etc...

Here's an example showing how to use the Phi-2 LLM:

litgpt chat microsoft/phi-2

>> Prompt: What do Llamas eat?

Full code:

# 1) List all supported LLMs
litgpt download list

# 2) Use a model (auto downloads weights)
litgpt chat microsoft/phi-2

>> Prompt: What do Llamas eat?

The download of certain models requires an additional access token. You can read more about this in the download documentation.

Read the full chat docs.

Pretrain an LLM

Pretraining is the process of teaching an AI model by exposing it to a large amount of data before it is fine-tuned for specific tasks.

Show code:

mkdir -p custom_texts
curl https://www.gutenberg.org/cache/epub/24440/pg24440.txt --output custom_texts/book1.txt
curl https://www.gutenberg.org/cache/epub/26393/pg26393.txt --output custom_texts/book2.txt

# 1) Download a tokenizer
litgpt download EleutherAI/pythia-160m \
  --tokenizer_only True

# 2) Pretrain the model
litgpt pretrain EleutherAI/pythia-160m \
  --tokenizer_dir EleutherAI/pythia-160m \
  --data TextFiles \
  --data.train_data_path "custom_texts/" \
  --train.max_tokens 10_000_000 \
  --out_dir out/custom-model

# 3) Test the model
litgpt chat out/custom-model/final

Read the full pretraining docs

Continue pretraining an LLM

Continued pretraining is another way of finetuning that specializes an already pretrained model by training on custom data:

Show code:

mkdir -p custom_texts
curl https://www.gutenberg.org/cache/epub/24440/pg24440.txt --output custom_texts/book1.txt
curl https://www.gutenberg.org/cache/epub/26393/pg26393.txt --output custom_texts/book2.txt

# 1) Continue pretraining a model (auto downloads weights)
litgpt pretrain EleutherAI/pythia-160m \
  --tokenizer_dir EleutherAI/pythia-160m \
  --initial_checkpoint_dir EleutherAI/pythia-160m \
  --data TextFiles \
  --data.train_data_path "custom_texts/" \
  --train.max_tokens 10_000_000 \
  --out_dir out/custom-model

# 2) Test the model
litgpt chat out/custom-model/final

Read the full continued pretraining docs

State-of-the-art features

✅ State-of-the-art optimizations: Flash Attention v2, multi-GPU support via fully-sharded data parallelism, optional CPU offloading, and TPU and XLA support.
✅ Pretrain, finetune, and deploy
✅ Reduce compute requirements with low-precision settings: FP16, BF16, and FP16/FP32 mixed.
✅ Lower memory requirements with quantization: 4-bit floats, 8-bit integers, and double quantization.
✅ Configuration files for great out-of-the-box performance.
✅ Parameter-efficient finetuning: LoRA, QLoRA, Adapter, and Adapter v2.
✅ Exporting to other popular model weight formats.
✅ Many popular datasets for pretraining and finetuning, and support for custom datasets.
✅ Readable and easy-to-modify code to experiment with the latest research ideas.

Training recipes

LitGPT comes with validated recipes (YAML configs) to train models under different conditions. We've generated these recipes based on the parameters we found to perform the best for different training conditions.

Browse all training recipes here.

Example

litgpt finetune \
  --config https://raw.githubusercontent.com/Lightning-AI/litgpt/main/config_hub/finetune/llama-2-7b/lora.yaml

✅ Use configs to customize training

Configs let you customize training for all granular parameters like:

# The path to the base model's checkpoint directory to load for finetuning. (type: <class 'Path'>, default: checkpoints/stabilityai/stablelm-base-alpha-3b)
checkpoint_dir: checkpoints/meta-llama/Llama-2-7b-hf

# Directory in which to save checkpoints and logs. (type: <class 'Path'>, default: out/lora)
out_dir: out/finetune/qlora-llama2-7b

# The precision to use for finetuning. Possible choices: "bf16-true", "bf16-mixed", "32-true". (type: Optional[str], default: null)
precision: bf16-true

...

✅ Example: LoRA finetuning config

# The path to the base model's checkpoint directory to load for finetuning. (type: <class 'Path'>, default: checkpoints/stabilityai/stablelm-base-alpha-3b)
checkpoint_dir: checkpoints/meta-llama/Llama-2-7b-hf

# Directory in which to save checkpoints and logs. (type: <class 'Path'>, default: out/lora)
out_dir: out/finetune/qlora-llama2-7b

# The precision to use for finetuning. Possible choices: "bf16-true", "bf16-mixed", "32-true". (type: Optional[str], default: null)
precision: bf16-true

# If set, quantize the model with this algorithm. See ``tutorials/quantize.md`` for more information. (type: Optional[Literal['nf4', 'nf4-dq', 'fp4', 'fp4-dq', 'int8-training']], default: null)
quantize: bnb.nf4

# How many devices/GPUs to use. (type: Union[int, str], default: 1)
devices: 1

# How many nodes to use. (type: int, default: 1)
num_nodes: 1

# The LoRA rank. (type: int, default: 8)
lora_r: 32

# The LoRA alpha. (type: int, default: 16)
lora_alpha: 16

# The LoRA dropout value. (type: float, default: 0.05)
lora_dropout: 0.05

# Whether to apply LoRA to the query weights in attention. (type: bool, default: True)
lora_query: true

# Whether to apply LoRA to the key weights in attention. (type: bool, default: False)
lora_key: false

# Whether to apply LoRA to the value weights in attention. (type: bool, default: True)
lora_value: true

# Whether to apply LoRA to the output projection in the attention block. (type: bool, default: False)
lora_projection: false

# Whether to apply LoRA to the weights of the MLP in the attention block. (type: bool, default: False)
lora_mlp: false

# Whether to apply LoRA to output head in GPT. (type: bool, default: False)
lora_head: false

# Data-related arguments. If not provided, the default is ``litgpt.data.Alpaca``.
data:
  class_path: litgpt.data.Alpaca2k
  init_args:
    mask_prompt: false
    val_split_fraction: 0.05
    prompt_style: alpaca
    ignore_index: -100
    seed: 42
    num_workers: 4
    download_dir: data/alpaca2k

# Training-related arguments. See ``litgpt.args.TrainArgs`` for details
train:

  # Number of optimizer steps between saving checkpoints (type: Optional[int], default: 1000)
  save_interval: 200

  # Number of iterations between logging calls (type: int, default: 1)
  log_interval: 1

  # Number of samples between optimizer steps across data-parallel ranks (type: int, default: 128)
  global_batch_size: 8

  # Number of samples per data-parallel rank (type: int, default: 4)
  micro_batch_size: 2

  # Number of iterations with learning rate warmup active (type: int, default: 100)
  lr_warmup_steps: 10

  # Number of epochs to train on (type: Optional[int], default: 5)
  epochs: 4

  # Total number of tokens to train on (type: Optional[int], default: null)
  max_tokens:

  # Limits the number of optimizer steps to run (type: Optional[int], default: null)
  max_steps:

  # Limits the length of samples (type: Optional[int], default: null)
  max_seq_length: 512

  # Whether to tie the embedding weights with the language modeling head weights (type: Optional[bool], default: null)
  tie_embeddings:

  #   (type: float, default: 0.0003)
  learning_rate: 0.0002

  #   (type: float, default: 0.02)
  weight_decay: 0.0

  #   (type: float, default: 0.9)
  beta1: 0.9

  #   (type: float, default: 0.95)
  beta2: 0.95

  #   (type: Optional[float], default: null)
  max_norm:

  #   (type: float, default: 6e-05)
  min_lr: 6.0e-05

# Evaluation-related arguments. See ``litgpt.args.EvalArgs`` for details
eval:

  # Number of optimizer steps between evaluation calls (type: int, default: 100)
  interval: 100

  # Number of tokens to generate (type: Optional[int], default: 100)
  max_new_tokens: 100

  # Number of iterations (type: int, default: 100)
  max_iters: 100

# The name of the logger to send metrics to. (type: Literal['wandb', 'tensorboard', 'csv'], default: csv)
logger_name: csv

# The random seed to use for reproducibility. (type: int, default: 1337)
seed: 1337

✅ Override any parameter in the CLI:

litgpt finetune \
  --config https://raw.githubusercontent.com/Lightning-AI/litgpt/main/config_hub/finetune/llama-2-7b/lora.yaml \
  --lora_r 4

Project highlights

LitGPT powers many great AI projects, initiatives, challenges and of course enterprises. Please submit a pull request to be considered for a feature.

📊 SAMBA: Simple Hybrid State Space Models for Efficient Unlimited Context Language Modeling

The Samba project by researchers at Microsoft is built on top of the LitGPT code base and combines state space models with sliding window attention, which outperforms pure state space models.

🏆 NeurIPS 2023 Large Language Model Efficiency Challenge: 1 LLM + 1 GPU + 1 Day

The LitGPT repository was the official starter kit for the NeurIPS 2023 LLM Efficiency Challenge, which is a competition focused on finetuning an existing non-instruction tuned LLM for 24 hours on a single GPU.

🦙 TinyLlama: An Open-Source Small Language Model

LitGPT powered the TinyLlama project and TinyLlama: An Open-Source Small Language Model research paper.

🍪 MicroLlama: MicroLlama-300M

MicroLlama is a 300M Llama model pretrained on 50B tokens powered by TinyLlama and LitGPT.

🔬 Pre-training Small Base LMs with Fewer Tokens

The research paper "Pre-training Small Base LMs with Fewer Tokens", which utilizes LitGPT, develops smaller base language models by inheriting a few transformer blocks from larger models and training on a tiny fraction of the data used by the larger models. It demonstrates that these smaller models can perform comparably to larger models despite using significantly less training data and resources.

Community

We welcome all individual contributors, regardless of their level of experience or hardware. Your contributions are valuable, and we are excited to see what you can accomplish in this collaborative and supportive environment.

Tutorials

🚀 Get started
⚡️ Finetuning, incl. LoRA, QLoRA, and Adapters
🤖 Pretraining
💬 Model evaluation
📘 Supported and custom datasets
🧹 Quantization
🤯 Tips for dealing with out-of-memory (OOM) errors
🧑🏽‍💻 Using cloud TPUs

Acknowledgments

This implementation extends on Lit-LLaMA and nanoGPT, and it's powered by Lightning Fabric ⚡.

@karpathy for nanoGPT
@EleutherAI for GPT-NeoX and the Evaluation Harness
@TimDettmers for bitsandbytes
@Microsoft for LoRA
@tridao for Flash Attention 2

License

LitGPT is released under the Apache 2.0 license.

Citation

If you use LitGPT in your research, please cite the following work:

@misc{litgpt-2023,
  author       = {Lightning AI},
  title        = {LitGPT},
  howpublished = {\url{https://github.com/Lightning-AI/litgpt}},
  year         = {2023},
}

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