Custom Models

Add your own models locally without a rebuild, or contribute a model to the built-in catalog.

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Adding your own models locally (no rebuild needed)

You don't need to modify llmfit or wait for a release to see extra models. Create a custom_models.json in llmfit's data directory:

• Linux: ~/.local/share/llmfit/custom_models.json
• macOS: ~/Library/Application Support/llmfit/custom_models.json
• Windows: %APPDATA%\llmfit\custom_models.json

(or point the LLMFIT_CUSTOM_MODELS env var at any path). The file is a JSON array using the same entry format as the built-in catalog — see llmfit-core/data/schema.json; only a few fields are required:

[
  {
    "name": "my-org/My-Model-7B",
    "provider": "my-org",
    "parameter_count": "7B",
    "min_ram_gb": 5.0,
    "recommended_ram_gb": 8.0,
    "min_vram_gb": 5.0,
    "quantization": "Q4_K_M",
    "context_length": 32768,
    "use_case": "General chat"
  }
]

Custom entries with the same name as a catalog model override it; new names are added. Optional fields (is_moe, num_hidden_layers, gguf_sources, …) improve estimate accuracy when provided. You can also run llmfit update to fetch trending models from HuggingFace without a rebuild.

Adding a model to the built-in catalog

1. Add the model's HuggingFace repo ID (e.g., meta-llama/Llama-3.1-8B) to the TARGET_MODELS list in scripts/scrape_hf_models.py.
2. If the model is gated (requires HuggingFace authentication to access metadata), add a fallback entry to the FALLBACKS list in the same script with the parameter count and context length.
3. Run the automated update script:
   shCopy

   make update-models
   # or: ./scripts/update_models.sh
   

4. Verify the updated model list: ./target/release/llmfit list
5. Update MODELS.md by running: python3 << 'EOF' < scripts/... (see commit history for the generator script)
6. Open a pull request.

See MODELS.md for the current list and AGENTS.md for architecture details.