What is Data Annotation?

Data annotation is the process of preprocessing data in order to make it usable for machine learning. The word “annotation” refers to any metadata tag used to mark up elements of a dataset. Adding meaningful metadata to the original dataset provides a layer of rich information for input into machine learning models.

It’s simply not enough to give a computer a large amount of data and expect it to learn – data has to undergo some preparation in order for computers to find patterns and inferences within it. For machine learning models to learn efficiently and effectively, data annotation must be accurate and relevant to the task the machine is being asked to perform. For this reason, large scale human-annotation services are key to successful machine learning. Lionbridge AI provides high-quality data annotation services for machine learning use cases. Our network of 500,000+ qualified annotators processes millions of data points to build premium ground truth data for text, images, videos, and audio across 300+ languages.

Why Lionbridge?

No matter what your needs are, the Lionbridge platform is capable of processing all kinds of text, image, video and audio data requests.

  • 500,000+ Contributors
  • 300+ Languages
  • 20+ Years of experience


With 20+ years of experience, Lionbridge provides data annotation solutions to the world’s largest companies.


The Lionbridge quality assurance system features built-in validation, spot-checking and a workers seniority system to ensure the highest quality data to train machine learning applications.


With access to a crowd of 500,000+ qualified annotators in 300+ languages, Lionbridge can quickly process hundreds of thousands of data rows so your models get the information they need to work in the real world.

Our Data Annotation Services

Text Annotation

With a background in natural language and linguistics, Lionbridge is a well equipped to handle any kind of text annotation project. Whether you’re training an entity extraction system or sentiment analysis tool, our curated crowd can accurately label text data in 300+ languages and dialects.

Audio Annotation

Develop, calibrate, and improve voice-enabled applications with outsourced audio annotation services. Lionbridge’s network of 500,000+ qualified linguists, in-country speakers and experienced project management team has deep experience collecting and annotating audio data for machine learning.

Image Annotation

Our qualified contributors source, annotate, and prepare images for input into machine learning software. Power your computer vision models to recognize and process visual data with meticulously tagged image data.


Video Annotation

Build comprehensively labeled video datasets with Lionbridge’s suite of video annotation services. From object localization to video tracking, Lionbridge has the experience and technology necessary to serve all of your video annotation needs.


How does Lionbridge’s Data Annotation Services work?

how to crowdsource data

1. Project set-up

Our team will work with you to develop a custom solution based on your project objectives and timeline.

how to crowdsource data
how to crowdsource data

2. Production

Our crowd of multilingual experts get to work evaluating and reviewing your advertisements.

how to crowdsource data
how to crowdsource data

3. Delivery

Our project management team check, package and format the data before being sent to you for final approval.

how to crowdsource data

Sentiment Analysis Case Study

Learn how Lionbridge helped one of the world’s biggest technology companies collect and annotate 20,000+ text records to train their text analysis engine.

  • 20,000+ Text Records
  • 14 Languages
  • 1,000+ Hours of Word Completed



Data Annotation Pricing

How much do data annotation services cost?
Our proprietary platform streamlines much of the annotation process, allowing us to offer the most cost-effective annotation solution in the industry.

Contact us to get a free estimate for your project.

  • Account Manager
  • Project Management
  • 24/7 Support
  • API
  • NDA
  • Volume pricing
  • Custom reporting
  • Enterprise-grade SLAs
  • Custom invoicing
  • Consulting services
Get in touch with our team today

Multilingual Data Annotation Services

Most other data annotation companies don’t support languages other than English at scale. By contrast, Lionbridge provides data annotation across 300+ languages and dialects. Some of our most popular languages include:

  • Chinese data annotation
  • Dutch data annotation
  • French data annotation
  • German data annotation
  • Italian data annotation
  • Japanese data annotation
  • Portuguese data annotation
  • Spanish data annotation

Learn more about Data Annotation

It's only logical to ask how much training data you need, but it can be a complicated question. Let's see why, before looking at ways to determine the right amount of data.
Wondering which image annotation types best suit your project? In this article, we introduce five types of image annotation and some of their applications.
Data annotation is the task of labeling data, which could be in any form such as text, audio, images, or video. In this article, we’ll explore the different types and uses for data annotation in machine learning.