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Custom Translator

Custom Translator is a feature of the Translator service. With Custom Translator, enterprises, app developers, and language service providers can build neural translation systems that understand the terminology used in their own business and industry. The customized translation system will then seamlessly integrate into existing applications, workflows and websites.

Custom Translator allows users to customize Translator’s advanced neural machine translation for Translator’s supported neural translation languages. With Custom Translator, you can customize text using the Translator service on Azure, and speech translation using the Speech service on Azure.

Why should I use Custom Translator?

Get Better Translations

Use your previously translated documents (leaflets, webpages, documentation, etc.) to build a translation system that reflects your domain-specific terminology and style, better than a standard translation system. Users can upload TMX, XLIFF, TXT, DOCX, and XLSX documents.

To make data collection and preparation more effective, the system also accepts data that is parallel at the document level but is not yet aligned at the sentence level. If users have access to versions of the same content in multiple languages but in separate documents, Custom Translator will be able to automatically match sentences across documents. The system can also use monolingual data in either or both languages to complement the parallel training data to improve the translations.

Given the appropriate type and amount of training data it is not uncommon to expect gains between 5 and 10, or even more BLEU points on translation quality by using Custom Translator.


Be productive and cost effective

Training and deploying a custom system is easy and does not require any programming skills.

Using the secure Custom Translator portal, users can upload training data through an intuitive interface, train systems, test them right from the portal and deploy them to a production environment with a simple click. The system will then be available for use at scale within a few hours (actual time depends on training data size).

Custom Translator can also be programmatically accessed through a dedicated API. This allows users that create or update training on a regular basis to manage these processes through their own app or web service.

For paid tiers (S1-S4), deployed custom models are retained for their lifetime, and undeployed models are retained for 12 months since their last training or evaluation, or the model’s undeployment. For the free tier (F0), deployment is not available and models are retained for 3 months after training.

View Custom Translator pricing


Securely translate anytime, anywhere on all your apps and services

Translation systems built with Custom Translator are available through the same cloud-based, high performance, highly scalable Translator service on Azure that powers billions of translations every day. Custom systems can be seamlessly accessed and integrated into any product or business workflow, and on any device, via the Translator or Speech services on Azure, through standard REST technology.

How do I get started?

1. Ensure you have a Translator key
If you don’t have a key already, learn how to sign up

2. Watch the how to video and read the user guide
The video below will give you a quick overview for how to use Custom Translator and the Custom Translator documentation will teach you everything you need to know to start customizing your translations

3. Log into the Custom Translator portal
You can use your Microsoft account or corporate email to sign into the portal

4. Questions?
Ask them on Stack Overflow. We monitor these daily!

Start customizing your NMT

View a comprehensive getting started video on YouTube.

Note: Customization using Custom Translator is not available with subscriptions on

Learn more

This service is part of Microsoft Cognitive Services