---
language:
- multilingual
language_details: "NLLB-200 supports 200 languages (see facebook/nllb-200-distilled-600M)"
license: "cc-by-nc-4.0"
tags:
- translation
- coreml
- nllb
- apple
- ios
- mlpackage
pipeline_tag: translation
datasets:
- flores-200
base_model: facebook/nllb-200-distilled-600M
---

# NLLB-200 Core ML 512 (KV decoders)

Core ML export of [facebook/nllb-200-distilled-600M](https://huggingface.co/facebook/nllb-200-distilled-600M) with **max sequence length 512** for encoder and decoder.

## Layout

| Artifact | Role |
|----------|------|
| `NLLB_Encoder_512.mlpackage` | Encoder |
| `NLLB_Decoder_512_init.mlpackage` | First autoregressive step + initial KV |
| `NLLB_Decoder_512_step.mlpackage` | Later steps; past KV in/out |
| `tokenizer/` | Hugging Face tokenizer files |
| `config.json` | Base model config copy |

**Do not** use a single legacy `NLLB_Decoder_512.mlpackage` only: greedy decoding breaks when the graph was traced with a fixed short prefix.

The **palettized** repo (`nllb200-coreml-512-pal8`) uses the same three `mlpackage` names with 8-bit weight palettization.

## App

on-device iOS client model IDs: `nllb200-coreml-512`, `nllb200-coreml-512-pal8` (`NLLBCoreMLTranslationService`).

## Conversion

Produced from [nllb200_coreml_colab_v3_fixed.ipynb](local iOS project (private)) (same KV pipeline as 1024, `enc_len=512`).

## Validation (macOS)

```bash
python3 Scripts/validate_nllb512_bleu_macos.py --local-dir Notebooks/nllb/output/nllb200-coreml-512 --min-bleu 50
```

## License

Same as the base model ([CC-BY-NC-4.0](https://creativecommons.org/licenses/by-nc/4.0/)) and NLLB-200 terms.