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Folio supports English (en) and French (fr) documents, with automatic language detection (auto) enabled by default. Use the language form field to influence OCR accuracy and extraction quality.

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The language parameter

ValueBehaviour
autoFolio detects the document language automatically. This is the default.
enForce English OCR and extraction.
frForce French OCR and extraction.
curl -X POST https://api.glialhealth.com/v1/documents \
  -H "Authorization: Bearer sk_test_..." \
  -F file=@ordonnance.pdf \
  -F language=fr
The detected (or forced) language is echoed back in the document object’s language field: 
{
  "id": "doc_01j9xkqz...",
  "language": "fr",
  "status": "completed"
}

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When to use auto vs. explicit

Use auto (default) when:
  • Your document corpus contains a mix of English and French documents and you don’t know the language at submission time.
  • You want Folio to handle language detection without adding any logic on your side.
Use an explicit language (en or fr) when:
  • You know the document language in advance and want to avoid a small detection overhead.
  • OCR accuracy for a specific language is critical and you want to eliminate any ambiguity from the classifier.
  • Documents contain a mix of characters but should be treated as one primary language (e.g. an English form with a few French words).

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Bilingual documents

Some documents (e.g. Canadian government forms, Quebec-regulated health records) contain content in both English and French. In these cases:
  • Use auto: Folio will detect the dominant language and apply the best OCR model for that language. Fields in the secondary language are still extracted with reasonable accuracy.
  • Extraction field values are returned in whichever language they appear in the source document — Folio does not translate values.
If bilingual accuracy is critical for your use case, test both auto and each explicit language against a representative sample of your documents and compare the per-field confidence scores in the result.

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Language and extraction schemas

Language does not affect how extraction schemas are defined or applied. Schema key names, type constraints, and pattern checks are language-agnostic. When using hint values in a schema, writing the hint in the same language as the target documents may improve extraction accuracy.