transformers

Transformers

Overview

The Hugging Face Transformers library provides access to thousands of pre-trained models for tasks across NLP, computer vision, audio, and multimodal domains. Use this skill to load models, perform inference, and fine-tune on custom data.

Installation

Tested against transformers 5.12.0 (current PyPI release; June 2026). Requires Python 3.10+; the torch extra currently requires PyTorch 2.4+.

uv pip install "transformers[torch]==5.12.0" huggingface_hub==1.19.0 datasets==5.0.0 evaluate==0.4.6 accelerate==1.14.0

For vision tasks, add:

uv pip install timm==1.0.27 pillow==12.2.0

For audio tasks, add:

uv pip install librosa==0.11.0 soundfile==0.14.0

These pins are for reproducible examples. For exploratory work, loosen them only after checking the Transformers and Hub release notes for API changes.

Check your version:

import transformers
print(transformers.__version__)

Authentication

Many models on the Hugging Face Hub are gated or private. Authenticate before loading them.

Recommended: CLI login (stores token in ~/.cache/huggingface/token):

hf auth login

Python:

from huggingface_hub import login
login()  # Interactive prompt; do not hardcode tokens in scripts

Servers / CI: set HF_TOKEN in the environment (never commit tokens to git or shell profiles):

export HF_TOKEN="..."  # Read token from a secret manager, not source code

Get tokens at: https://huggingface.co/settings/tokens

Security: Never paste tokens into notebooks, repos, or shared configs. Prefer hf auth login over exporting tokens in .bashrc or .zshrc.

Use the narrowest token scope that works: read for private or gated model downloads, write only for uploads. If a long-running environment should not send the stored token on every Hub request, set HF_HUB_DISABLE_IMPLICIT_TOKEN=1 and pass a token only where authentication is required.

Transformers v5

Transformers v5 is PyTorch-only (TensorFlow and JAX backends were removed). For upgrades from v4, see the v5 migration guide. New projects should pair transformers 5.x with huggingface_hub 1.x.

Gated or custom architectures: accept the model license on the Hub, then load with trust_remote_code=True only when the model card requires custom code you have reviewed.

Cache location: set HF_HOME for all Hugging Face caches, or HF_HUB_CACHE just for Hub files. Use HF_HUB_OFFLINE=1 only after required model snapshots are already cached.

Quick Start

Use the Pipeline API for fast inference without manual configuration:

from transformers import pipeline

# Text generation (prefer max_new_tokens for causal LMs)
generator = pipeline("text-generation", model="Qwen/Qwen2.5-1.5B")
result = generator("The future of AI is", max_new_tokens=50)

# Text classification
classifier = pipeline("text-classification")
result = classifier("This movie was excellent!")

# Question answering
qa = pipeline("question-answering")
result = qa(question="What is AI?", context="AI is artificial intelligence...")

Core Capabilities

1. Pipelines for Quick Inference

Use for simple, optimized inference across many tasks. Supports text generation, classification, NER, question answering, summarization, translation, image classification, object detection, audio classification, and more.

When to use: Quick prototyping, simple inference tasks, no custom preprocessing needed.

See references/pipelines.md for comprehensive task coverage and optimization.

2. Model Loading and Management

Load pre-trained models with fine-grained control over configuration, device placement, and precision.

When to use: Custom model initialization, advanced device management, model inspection.

See references/models.md for loading patterns and best practices.

3. Text Generation

Generate text with LLMs using various decoding strategies (greedy, beam search, sampling) and control parameters (temperature, top-k, top-p).

When to use: Creative text generation, code generation, conversational AI, text completion.

See references/generation.md for generation strategies and parameters.

4. Training and Fine-Tuning

Fine-tune pre-trained models on custom datasets using the Trainer API with automatic mixed precision, distributed training, and logging.

When to use: Task-specific model adaptation, domain adaptation, improving model performance.

See references/training.md for training workflows and best practices.

5. Tokenization

Convert text to tokens and token IDs for model input, with padding, truncation, and special token handling.

When to use: Custom preprocessing pipelines, understanding model inputs, batch processing.

See references/tokenizers.md for tokenization details.

Common Patterns

Pattern 1: Simple Inference

For straightforward tasks, use pipelines:

pipe = pipeline("task-name", model="model-id")
output = pipe(input_data)

Pattern 2: Custom Model Usage

For advanced control, load model and tokenizer separately:

from transformers import AutoModelForCausalLM, AutoTokenizer

tokenizer = AutoTokenizer.from_pretrained("model-id")
model = AutoModelForCausalLM.from_pretrained("model-id", device_map="auto")

inputs = tokenizer("text", return_tensors="pt")
outputs = model.generate(**inputs, max_new_tokens=100)
result = tokenizer.decode(outputs[0])

Pattern 3: Fine-Tuning

For task adaptation, use Trainer:

from transformers import Trainer, TrainingArguments

training_args = TrainingArguments(
    output_dir="./results",
    num_train_epochs=3,
    per_device_train_batch_size=8,
)

trainer = Trainer(
    model=model,
    args=training_args,
    train_dataset=train_dataset,
)

trainer.train()

Reference Documentation

For detailed information on specific components:

• Pipelines: references/pipelines.md - All supported tasks and optimization
• Models: references/models.md - Loading, saving, and configuration
• Generation: references/generation.md - Text generation strategies and parameters
• Training: references/training.md - Fine-tuning with Trainer API
• Tokenizers: references/tokenizers.md - Tokenization and preprocessing