Translate Text API

Endpoint

POST /v2/translate

Base URLs

https://api-free.deepl.com/v2/translate  (Free API)
https://api.deepl.com/v2/translate       (Pro / Enterprise)

Request Parameters

Required Parameters

Parameter	Type	Description
`text`	string[]	Text(s) to translate. Up to 50 texts per request.
`target_lang`	string	Target language code (e.g., "DE", "FR", "JA").

Optional Parameters

Parameter	Type	Description
`source_lang`	string	Source language code. If omitted, auto-detected.
`context`	string	Additional context text to improve translation quality.
`split_sentences`	string	Sentence splitting mode: `"0"` (no splitting), `"1"` (punctuation-based), `"nonewlines"` (default, no splitting on newlines).
`preserve_formatting`	boolean	If `true`, preserve original formatting. Default: `true`.
`formality`	string	Formality preference: `"default"`, `"more"`, `"less"`, `"prefer_more"`, `"prefer_less"`.
`model_type`	string	Model to use: `"quality_optimized"` (default), `"latency_optimized"`, `"prefer_quality_optimized"`.
`glossary_id`	string	Glossary ID to apply. Up to 5 glossaries can be specified.
`style_id`	string	Style rule ID to apply for translation output style control.
`translation_memory_id`	string	Translation memory ID for reusing previously translated content.
`custom_instructions`	string	Custom translation instructions for fine-grained control.
`tag_handling`	string	XML/HTML tag handling: `"xml"` or `"html"`. Required when texts contain markup.
`outline_detection`	boolean	Enable automatic outline/list structure detection. Default: `true`.

Request Example (cURL)

curl -X POST 'https://api-free.deepl.com/v2/translate' \
  -H 'Authorization: DeepL-Auth-Key YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "text": ["Hello, world!", "How are you?"],
    "target_lang": "DE",
    "source_lang": "EN",
    "formality": "prefer_more",
    "preserve_formatting": true,
    "split_sentences": "1",
    "tag_handling": "xml",
    "outline_detection": true
  }'

Response Format (JSON)

{
  "translations": [
    {
      "detected_source_language": "EN",
      "text": "Hallo, Welt!"
    },
    {
      "detected_source_language": "EN",
      "text": "Wie geht es Ihnen?"
    }
  ]
}

Response Fields

Field	Type	Description
`translations`	array	Array of translation results, one per input text.
`detected_source_language`	string	Language code detected for the source text.
`text`	string	The translated text.

Error Handling

The API returns standard HTTP status codes:

200 — Request successful
400 — Bad request (invalid parameters)
403 — Invalid or missing API key
456 — Quota exceeded
500 — Internal server error

Rate Limits

Rate limits depend on your subscription plan. Free plans have lower limits. If you exceed the rate limit, the API returns HTTP 429. Implement exponential backoff for retry logic.

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