---
title: Wasla Feedback Moderation API
emoji: 🛡️
colorFrom: blue
colorTo: indigo
sdk: docker
app_port: 7860
pinned: false
---

# Feedback Moderation API

AI-powered microservice that detects toxic / abusive language in user-submitted text.  
Uses **local** Hugging Face transformer models — your data never leaves your infrastructure.

### Dual-Model Architecture

| Language | Model | Labels |
| -------- | ----- | ------ |
| English, French, Italian (and more) | `citizenlab/distilbert-base-multilingual-cased-toxicity` | `toxic` / `not_toxic` |
| Arabic | `Hate-speech-CNERG/dehatebert-mono-arabic` | `HATE` / `NON_HATE` |

Arabic text is **automatically detected** using the [lingua](https://github.com/pemistahl/lingua-py) language-detection library and routed to the dedicated Arabic hate-speech model for significantly higher accuracy (~87.8 %).  All other languages use the multilingual model.

### LLM Verification Layer (optional)

When the local classifier's confidence falls in a configurable **grey zone** (default: 0.40 – 0.85), the text is forwarded to a free **Hugging Face Inference API** LLM (default: `mistralai/Mistral-7B-Instruct-v0.3`) for a second opinion. The LLM score is blended with the local score (40/60 weighting) to produce a refined verdict.

- ⚡ **No extra latency** for clear-cut predictions (>95 % of requests)
- 🆓 **Free** — uses HF Inference Providers with a free token
- 🔒 **Graceful fallback** — if the LLM is unavailable, the local model result is used as-is

Set `HF_TOKEN` in `.env` to enable. Leave it empty to disable.

---

## Quick Start

### 1. Clone & create a virtual environment

```bash
git clone <your-repo-url> moderator-api
cd moderator-api
python -m venv venv

# Windows
.\venv\Scripts\Activate.ps1
# macOS / Linux
source venv/bin/activate
```

### 2. Install dependencies

```bash
pip install -r requirements.txt
```

### 3. Configure

Copy the example env file and set a strong API key:

```bash
cp .env.example .env
# then edit .env → MODERATOR_API_KEY=<your-secret>
```

### 4. Run

```bash
uvicorn main:app --reload
```

The server starts at **http://127.0.0.1:8000**.  
Interactive docs are at **http://127.0.0.1:8000/docs**.

> **First launch** will download two models (~1 GB total).  
> Subsequent starts load from the local cache.

---

## API Reference

### `GET /health`

Liveness probe. Returns `{"status": "ok", "model_loaded": true}`.

### `POST /api/v1/moderate`

Analyse a piece of text for toxicity.

**Headers**

| Header      | Required | Description          |
| ----------- | -------- | -------------------- |
| `X-API-Key` | ✅        | Your secret API key  |

**Request body**

```json
{
  "text": "This product is terrible and I hate everything about it!"
}
```

**Response**

```json
{
  "has_bad_words": true,
  "confidence": 0.9812,
  "label": "toxic",
  "detected_language": "en",
  "llm_verified": false
}
```

---

## Calling from an External App

```python
import requests

API_URL  = "http://your-server:8000/api/v1/moderate"
API_KEY  = "your-secret-api-key"

response = requests.post(
    API_URL,
    json={"text": "I absolutely love this!"},
    headers={"X-API-Key": API_KEY},
)
result = response.json()

if result["has_bad_words"]:
    print("⚠️  Feedback rejected — toxic content detected.")
else:
    print("✅  Feedback is clean.")
```

---

## Docker

### Build

```bash
docker build -t moderator-api .
```

### Run

```bash
docker run -d \
  -p 8000:8000 \
  -e MODERATOR_API_KEY=your-secret-api-key \
  --name moderator-api \
  moderator-api
```

---

## Deploy to Hugging Face Spaces (Free)

### 1. Create a Space

Go to [huggingface.co/new-space](https://huggingface.co/new-space) and create a new Space:
- **Space name**: `moderator-api`
- **SDK**: Docker
- **Visibility**: Private (recommended)

### 2. Add secrets

In your Space → **Settings → Secrets**, add:

| Secret | Value |
| ------ | ----- |
| `MODERATOR_API_KEY` | A strong random string |
| `HF_TOKEN` | Your Hugging Face token |
| `LLM_VERIFY_LOW` | `0.0` (or `0.40` for grey-zone only) |
| `LLM_VERIFY_HIGH` | `1.0` (or `0.85` for grey-zone only) |

### 3. Push your code

```bash
git init
git remote add space https://huggingface.co/spaces/YOUR_USERNAME/moderator-api
git add .
git commit -m "Deploy moderator API"
git push space main
```

### 4. Access your API

Once built, your API is live at:
```
https://YOUR_USERNAME-moderator-api.hf.space/api/v1/moderate
```

Interactive docs at:
```
https://YOUR_USERNAME-moderator-api.hf.space/docs
```

> ⚠️ First deploy takes ~5 minutes (model downloads ~1 GB).  
> Subsequent deploys use cached layers and are much faster.

---

## Configuration (Environment Variables)

| Variable              | Default                        | Description                                |
| --------------------- | ------------------------------ | ------------------------------------------ |
| `MODERATOR_API_KEY`   | `change-me-before-production`  | Secret key clients must send in headers    |
| `MODEL_NAME`          | `citizenlab/distilbert-base-multilingual-cased-toxicity` | Multilingual Hugging Face model (en/fr/it) |
| `ARABIC_MODEL_NAME`   | `Hate-speech-CNERG/dehatebert-mono-arabic` | Dedicated Arabic hate-speech model         |
| `TOXICITY_THRESHOLD`  | `0.70`                         | Confidence cutoff to flag text as toxic    |
| `ARABIC_TOXICITY_THRESHOLD` | `0.45`                    | Lower threshold for Arabic (model outputs lower scores) |
| `HF_TOKEN`            | *(empty — LLM disabled)*       | Free HF token to enable LLM verification  |
| `LLM_MODEL_NAME`      | `Qwen/Qwen2.5-72B-Instruct`   | LLM used for grey-zone verification       |
| `LLM_VERIFY_LOW`      | `0.40`                         | Lower bound of the grey zone               |
| `LLM_VERIFY_HIGH`     | `0.85`                         | Upper bound of the grey zone               |

---

## Project Structure

```
moderator-api/
├── main.py              # FastAPI application & moderation endpoint
├── requirements.txt     # Python dependencies
├── Dockerfile           # Production container image
├── .dockerignore        # Files excluded from Docker build
├── .env                 # Local environment variables (git-ignored)
├── .env.example         # Template for .env
├── .gitignore
└── README.md
```

## License

MIT