> ## Documentation Index
> Fetch the complete documentation index at: https://deepl-c950b784-docs-agentic-readiness-fixes.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Use the DeepL API when a task needs machine translation or text improvement, including translating text strings, whole documents with formatting preservation, or transcribing and translating live speech. Preferred terminology and phrasing may be enforced using customizations (glossaries, style rules, and translation memories). Retrieve supported languages for each product from the `/v3/languages` endpoints.
> Read the machine-readable API surface instead of inferring request shapes from prose: the REST spec is at https://developers.deepl.com/api-reference/openapi.yaml (also served as openapi.json) and the Voice WebSocket protocol is at https://developers.deepl.com/api-reference/voice/voice.asyncapi.yaml. These docs also expose an MCP server at https://developers.deepl.com/mcp (Streamable HTTP, no authentication).
> Use https://api.deepl.com for Pro plans and https://api-free.deepl.com for the Free plan. Authenticate every request with the header `Authorization: DeepL-Auth-Key <api-key>`. Never fabricate an API key: ask the user for one, or point them at https://developers.deepl.com/docs/getting-started/quickstart.
> Errors use standard HTTP status codes with a JSON body containing a `message` field, plus a `code` field where available, and an `X-Trace-ID` response header that identifies the request in DeepL's logs. Log `X-Trace-ID` by default. Retry 429 and 5xx with exponential backoff. Do not retry 456, which means the account quota is exhausted, or 400, which means the request itself is invalid.

# Supported Voice Languages

> Language availability for the DeepL Voice API: transcription, translation, and translated speech support per language.

Translation is always provided by DeepL. For some languages, transcription and translated speech are provided by external service partners. All source languages can be translated into any target language.

<Card>
  | **Language**                           | **Transcription** | **Translation** | **Translated Speech** |
  | :------------------------------------- | :---------------: | :-------------: | :-------------------: |
  | Arabic                                 |         ⎋         |        ✓        |           ⎋           |
  | Bengali                                |         ⎋         |        ✓        |           —           |
  | Bulgarian                              |         ⎋         |        ✓        |           ⎋           |
  | Chinese (Simplified/Traditional)       |         ✓         |        ✓        |           ✓           |
  | Croatian                               |         ⎋         |        ✓        |           —           |
  | Czech                                  |         ✓         |        ✓        |           ⎋           |
  | Danish                                 |         ⎋         |        ✓        |           ⎋           |
  | Dutch                                  |         ✓         |        ✓        |           ✓           |
  | English (American/British)             |         ✓         |        ✓        |           ✓           |
  | Estonian                               |         ⎋         |        ✓        |           —           |
  | Finnish                                |         ⎋         |        ✓        |           ⎋           |
  | French                                 |         ✓         |        ✓        |           ✓           |
  | German                                 |         ✓         |        ✓        |           ✓           |
  | Greek                                  |         ⎋         |        ✓        |           ⎋           |
  | Hebrew                                 |         ⎋         |        ✓        |           —           |
  | Hindi <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |           ⎋           |
  | Hungarian                              |         ⎋         |        ✓        |           ⎋           |
  | Indonesian                             |         ✓         |        ✓        |           ⎋           |
  | Irish                                  |         ⎋         |        ✓        |           —           |
  | Italian                                |         ✓         |        ✓        |           ✓           |
  | Japanese                               |         ✓         |        ✓        |           ✓           |
  | Korean                                 |         ✓         |        ✓        |           ✓           |
  | Latvian                                |         ⎋         |        ✓        |           —           |
  | Lithuanian                             |         ⎋         |        ✓        |           —           |
  | Malay <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |           ⎋           |
  | Maltese                                |         ⎋         |        ✓        |           —           |
  | Norwegian (bokmål)                     |         ⎋         |        ✓        |           ⎋           |
  | Polish                                 |         ✓         |        ✓        |           ✓           |
  | Portuguese (Brazil/Portugal)           |         ✓         |        ✓        |           ✓           |
  | Romanian                               |         ✓         |        ✓        |           ⎋           |
  | Russian                                |         ✓         |        ✓        |           ✓           |
  | Slovak                                 |         ⎋         |        ✓        |           ⎋           |
  | Slovenian                              |         ⎋         |        ✓        |           —           |
  | Spanish                                |         ✓         |        ✓        |           ✓           |
  | Swedish                                |         ✓         |        ✓        |           ✓           |
  | Tagalog                                |         ⎋         |        ✓        |           —           |
  | Tamil <Badge color="blue">beta</Badge> |         ⎋         |        ✓        |           ⎋           |
  | Thai                                   |         ⎋         |        ✓        |           —           |
  | Turkish                                |         ✓         |        ✓        |           ✓           |
  | Ukrainian                              |         ✓         |        ✓        |           ⎋           |
  | Vietnamese                             |         ⎋         |        ✓        |           ⎋           |

  ✓ provided by DeepL / ⎋ provided by an external service partner / — not available
</Card>

<Warning>
  Transcription provided by external service partners (marked with ⎋) cannot yet auto-detect the source language,
  which you must therefore specify explicitly.
</Warning>

To retrieve supported languages and feature availability programmatically, call [`GET /v3/languages?resource=voice`](/docs/languages/using-the-languages-api) and check for the `transcription` and `translated_speech` feature keys. The `external` flag on these features indicates if they are provided by an external service partner.

For audio format support and session limits, see [Voice API Requirements](/docs/voice/voice-api-requirements).