Added

• Added support for the /v3/languages and /v3/languages/resources endpoints
  in the DeepLClient class: getLanguagesForResource() and getLanguageResources().
  These return richer per-resource, per-feature language support than the v2
  language endpoint, including newer languages and features.
• Added new model classes LanguageSupport, LanguageResource, LanguageFeature,
  and ResourceFeature to represent the v3 language response shape.

Changed

• Migrated request bodies for /v2/translate, /v2/glossaries, and
  /v2/write/rephrase to application/json with correctly-typed fields
  (e.g. text is sent as an array, show_billed_characters as a boolean,
  tag lists as arrays, translation_memory_threshold as an integer).
• Send type as a query parameter on GET /v2/languages instead of in the
  request body.
• Enabled OpenAPI request and response validation for the mock-server CI jobs.

Added

• Added support for translation memories in text translation via
  TranslateTextOptions::TRANSLATION_MEMORY_ID and
  TranslateTextOptions::TRANSLATION_MEMORY_THRESHOLD.
• Added listTranslationMemories() method to the DeepLClient class for
  listing available translation memories.
• Added new model class TranslationMemoryInfo to represent translation memory data.

Fixed

• Set explicit image for gitlab release CI job to avoid missing $HOME issues.

Added

• Added new language constants from January 2026 API release of 81 new languages.
• Added PHP 8.4 and 8.5 to CI test matrix.
• Added support for style rules CRUD endpoints in the DeepLClient class: createStyleRule(), getStyleRule(), updateStyleRuleName(), updateStyleRuleConfiguredRules(), and deleteStyleRule().
• Added support for style rule custom instruction CRUD endpoints in the DeepLClient class: createStyleRuleCustomInstruction(),
  getStyleRuleCustomInstruction(), updateStyleRuleCustomInstruction(), and deleteStyleRuleCustomInstruction().

Please refer to the README for usage instructions.

Added

• Added tag_handling_version parameter to translateText() specify which version of the tag handling algorithm to use. Options are v1 and v2.

Added

• Added custom_instructions parameter to translateText() to customize translation behavior with up to 10 instructions (max 300 characters each). Only supported for target languages: de, en, es, fr, it, ja, ko, zh and their variants. Note: using the custom_instructions parameter will use the quality_optimized model type as the default. Requests combining custom_instructions and the latency_optimized model type will be rejected.

• Added support for the GET /v3/style_rules endpoint in the client library, the implementation can be found in the DeepLClient class. Please refer to the README for usage instructions
• Added style_id option to translateText() which allows text translation with style rules.
• Added new model classes: StyleRuleInfo, ConfiguredRules, and CustomInstruction to support style rules functionality.

Added

• Added extraRequestParameters option to text and document translation methods to pass arbitrary parameters in the request body. This can be used to access beta features or override built-in parameters (such as target_lang, source_lang, etc.).

Added

• Added support for the /v3 Multilingual Glossary APIs in the client library while providing backwards compatability for the previous /v2 Glossary endpoints. Please refer to the README or upgrading_to_multilingual_glossaries.md for usage instructions.

Fixed

• Fixed DeepLClientOptions wrongly inheriting from TranslateTextOptions,
  when it should be TranslatorOptions.
  • Thanks to VincentLanglet for the
    report

Added

• Added support for the Write API in the client library, the implementation
  can be found in the DeepLClient class. Please refer to the README for usage
  instructions.

Changed

• The main functionality of the library is now also exposed via the DeepLClient
  class. Please change your code to use this over the Translator class whenever
  convenient.