⭐ GLiClass: Generalist and Lightweight Model for Sequence Classification

GLiClass is an efficient, zero-shot sequence classification model inspired by the GLiNER framework. It achieves comparable performance to traditional cross-encoder models while being significantly more computationally efficient, offering classification results approximately 10 times faster by performing classification in a single forward pass.

📄 Blog   •   📢 Discord   •   📺 Demo   •   🤗 Available models   •  

🚀 Quick Start

Install GLiClass easily using pip:

pip install gliclass

Install from Source

Clone and install directly from GitHub:

git clone https://github.com/Knowledgator/GLiClass
cd GLiClass

python -m venv venv
source venv/bin/activate  # Windows: venv\Scripts\activate

pip install -r requirements.txt
pip install .

Verify your installation:

import gliclass
print(gliclass.__version__)

🧑‍💻 Usage Example

from gliclass import GLiClassModel, ZeroShotClassificationPipeline
from transformers import AutoTokenizer

model = GLiClassModel.from_pretrained("knowledgator/gliclass-small-v1.0")
tokenizer = AutoTokenizer.from_pretrained("knowledgator/gliclass-small-v1.0")

pipeline = ZeroShotClassificationPipeline(
    model, tokenizer, classification_type='multi-label', device='cuda:0'
)

text = "One day I will see the world!"
labels = ["travel", "dreams", "sport", "science", "politics"]
results = pipeline(text, labels, threshold=0.5)[0]

for result in results:
    print(f"{result['label']} => {result['score']:.3f}")

🔥 New Features

Hierarchical Labels

GLiClass now supports hierarchical label structures using dot notation:

hierarchical_labels = {
    "sentiment": ["positive", "negative", "neutral"],
    "topic": ["product", "service", "shipping"]
}

text = "The product quality is amazing but delivery was slow"
results = pipeline(text, hierarchical_labels, threshold=0.5)[0]

for result in results:
    print(f"{result['label']} => {result['score']:.3f}")
# Output:
# sentiment.positive => 0.892
# topic.product => 0.921
# topic.shipping => 0.763

Get hierarchical output matching your input structure:

results = pipeline(text, hierarchical_labels, return_hierarchical=True)[0]
print(results)
# Output:
# {
#     "sentiment": {"positive": 0.892, "negative": 0.051, "neutral": 0.124},
#     "topic": {"product": 0.921, "service": 0.153, "shipping": 0.763}
# }

Few-Shot Examples

Improve classification accuracy with in-context examples using the <<EXAMPLE>> token:

examples = [
    {
        "text": "Love this item, great quality!",
        "labels": ["positive", "product"]
    },
    {
        "text": "Customer support was unhelpful",
        "labels": ["negative", "service"]
    }
]

text = "Fast delivery and the item works perfectly!"
labels = ["positive", "negative", "product", "service", "shipping"]

results = pipeline(text, labels, examples=examples, threshold=0.5)[0]

for result in results:
    print(f"{result['label']} => {result['score']:.3f}")

Task Description Prompts

Add custom prompts to guide the classification task:

text = "The battery life on this phone is incredible"
labels = ["positive", "negative", "neutral"]

results = pipeline(
    text,
    labels,
    prompt="Classify the sentiment of this product review:",
    threshold=0.5
)[0]

Use per-text prompts for batch processing:

texts = ["Review about electronics", "Review about clothing"]
prompts = [
    "Analyze this electronics review:",
    "Analyze this clothing review:"
]

results = pipeline(texts, labels, prompt=prompts)

Long Document Classification

Process long documents with automatic text chunking:

from gliclass import ZeroShotClassificationWithChunkingPipeline

chunking_pipeline = ZeroShotClassificationWithChunkingPipeline(
    model,
    tokenizer,
    text_chunk_size=8192,
    text_chunk_overlap=256,
    labels_chunk_size=8
)

long_document = "..." # Very long text
labels = ["category1", "category2", "category3"]

results = chunking_pipeline(long_document, labels, threshold=0.5)

🌟 Retrieval-Augmented Classification (RAC)

With new models trained with retrieval-agumented classification, such as this model you can specify examples to improve classification accuracy:

example = {
    "text": "A new machine learning platform automates complex data workflows but faces integration issues.",
    "all_labels": ["AI", "automation", "data_analysis", "usability", "integration"],
    "true_labels": ["AI", "integration", "automation"]
}

text = "The new AI-powered tool streamlines data analysis but has limited integration capabilities."
labels = ["AI", "automation", "data_analysis", "usability", "integration"]

results = pipeline(text, labels, threshold=0.1, rac_examples=[example])[0]

for predict in results:
    print(f"{predict['label']} => {predict['score']:.3f}")

🎯 Key Use Cases

• Sentiment Analysis: Rapidly classify texts as positive, negative, or neutral.
• Document Classification: Efficiently organize and categorize large document collections.
• Search Results Re-ranking: Improve relevance and precision by reranking search outputs.
• News Categorization: Automatically tag and organize news articles into predefined categories.
• Fact Checking: Quickly validate and categorize statements based on factual accuracy.

🛠️ How to Train

Prepare your training data as follows:

[
  {"text": "Sample text.", "all_labels": ["sports", "science", "business"], "true_labels": ["sports"]},
  ...
]

Optionally, specify confidence scores explicitly:

[
  {"text": "Sample text.", "all_labels": ["sports", "science"], "true_labels": {"sports": 0.9}},
  ...
]

Please, refer to the train.py script to set up your training from scratch or fine-tune existing models.

⚙️ Advanced Configuration

Architecture Types

GLiClass supports multiple architecture types:

• uni-encoder: Single encoder for both text and labels (default, most efficient)
• bi-encoder: Separate encoders for text and labels
• bi-encoder-fused: Bi-encoder with label embeddings fused into text encoding
• encoder-decoder: Encoder-decoder architecture for sequence-to-sequence tasks

from gliclass import GLiClassBiEncoder

# Load a bi-encoder model
model = GLiClassBiEncoder.from_pretrained("knowledgator/gliclass-biencoder-v1.0")

Pooling Strategies

Configure how token embeddings are pooled:

• first: First token (CLS token)
• avg: Average pooling
• max: Max pooling
• last: Last token
• sum: Sum pooling
• rms: Root mean square pooling
• abs_max: Max of absolute values
• abs_avg: Average of absolute values

from gliclass import GLiClassModelConfig

config = GLiClassModelConfig(
    pooling_strategy='avg',
    class_token_pooling='average'  # or 'first'
)

Scoring Mechanisms

Choose different scoring mechanisms for classification:

• simple: Dot product (fastest)
• weighted-dot: Weighted dot product with learned projections
• mlp: Multi-layer perceptron scorer
• hopfield: Hopfield network-based scorer

config = GLiClassModelConfig(
    scorer_type='mlp'
)

Flash Attention Backends

Enable Flash Attention for faster inference (requires additional packages):

# Install flash backends
pip install flashdeberta  # For DeBERTa models
pip install turbot5       # For T5 models

# Enable in config
config = GLiClassModelConfig(
    use_flash=True
)

📚 Citations

If you find GLiClass useful in your research or project, please cite our papers:

@misc{stepanov2025gliclassgeneralistlightweightmodel,
      title={GLiClass: Generalist Lightweight Model for Sequence Classification Tasks}, 
      author={Ihor Stepanov and Mykhailo Shtopko and Dmytro Vodianytskyi and Oleksandr Lukashov and Alexander Yavorskyi and Mykyta Yaroshenko},
      year={2025},
      eprint={2508.07662},
      archivePrefix={arXiv},
      primaryClass={cs.LG},
      url={https://arxiv.org/abs/2508.07662}, 
}