LLMLab

Test, compare, and evaluate LLM outputs across providers — all from one UI.

LLMLab is a local-first tool for prompt engineering and model evaluation. Pick a task, choose your models, tweak the prompt, and compare results side by side — with built-in LLM-as-judge scoring.

What it does

• 8 task types — Summarize, Classify, Extract, Translate, Generate, Rewrite, Analyze, Web Search — each with task-specific config options
• 8 providers — Anthropic, OpenAI, Gemini, DeepSeek, Groq, OpenRouter, Hugging Face, Ollama (local)
• Compare mode — Run 2-5 models on the same prompt, see outputs side by side
• LLM-as-judge evaluation — Score outputs on criteria like relevance, coherence, helpfulness using a separate judge model (G-Eval style, 1-5 scale with reasoning)
• Self-evaluation metrics — Task-specific metrics appended to the prompt (e.g., Conciseness, Coverage for Summarize)
• System prompt & sampling controls — Set persona, temperature, top-p per run
• Prompt preview & editing — See and modify the exact prompt before sending
• Run history — Every run is saved locally for replay
• File upload — PDF, TXT, CSV, JSON, images depending on task

Quick Start

# Clone
git clone https://github.com/ashwinbaldawa/llmlab.git
cd llmlab

# Install backend
pip install -e .

# Install frontend
cd frontend && npm install && cd ..

# Run (starts both backend + frontend dev server)
llmlab

Open http://localhost:3000. Add an API key in the Run Settings popup, and you're running.

Architecture

llmlab/
├── llmlab/                 # Python backend (FastAPI + litellm)
│   ├── server.py           # API endpoints: /api/chat, /api/chat/compare, /api/evaluate
│   ├── providers.py        # Provider config, model discovery via litellm registry
│   ├── evaluation.py       # LLM-as-judge engine (G-Eval rubrics, pointwise scoring)
│   └── cli.py              # CLI entry point
├── frontend/               # React frontend (Vite)
│   └── src/
│       ├── App.jsx          # Main app (~1200 lines, single-file for now)
│       ├── components/      # CompareView, ModelPicker, FileZone, etc.
│       ├── data/            # Task definitions, provider metadata
│       └── utils/           # Eval metrics, file helpers, markdown renderer, history
├── tests/                  # pytest backend tests (99 tests)
└── pyproject.toml          # Package config

Backend: FastAPI serves the API. All LLM calls go through litellm, which normalizes the interface across providers. Models are discovered dynamically from litellm's registry — no hardcoded model lists.

Frontend: React SPA with Vite. No UI framework — all inline styles. The frontend proxies /api/* to the backend during development.

API Keys

Keys are entered in the Run Settings popup (shown before each run) and stay in browser memory only — never stored on disk or sent anywhere except to the respective provider's API.

Evaluation

Self-eval metrics

Each task has built-in metrics (e.g., Conciseness, Coverage for Summarize). When selected, these are appended to the prompt asking the model to self-score 1-5.

LLM-as-judge

After generation, a separate judge model scores each output on selected criteria (relevance, coherence, helpfulness, faithfulness, etc.) using G-Eval style rubrics. Works in both single and compare mode.

Development

# Backend tests
pytest tests/ -q

# Frontend tests
cd frontend && npx vitest run

# Dev server with hot reload
llmlab --dev

Using Ollama (free, local)

ollama pull llama3.2
ollama serve

The app detects Ollama automatically on localhost:11434. No API key needed.

License

MIT