Data Annotation Services

Perfect your training data using expert project managers, 1 million contributors, and a customizable annotation platform.

What is Data Annotation?

Data annotation is the process of adding metadata, in the form of labels, to your data for machine learning purposes. Whether you're working with text, images, or audio, it's these labels that help machine learning models to understand variables within your dataset. However, data usually isn't prepackaged with clean, comprehensive tags. In fact, the need for labels is almost as diverse as the need for the models they help to build. Whatever you're building, having the right resources to tag your data at scale is the difference between success and failure.

At Lionbridge, our crowd of experts can annotate any type of data using our custom-built annotation tools. If you already have a team in place, you can also license our platform for annotation projects of any scale. Whatever your level of engagement, we can help you to build detail-rich datasets that take your model to the next level. 

Audio Data Image and Video Data Text Data

We supply the world's leading companies with data annotation outsourcing

Our Data Annotation Services


Image Annotation

At Lionbridge, we can annotate datasets of any size with anything from bounding boxes to polygons and landmarks.

Video Annotation

Our versatile tech platform allows us to annotate video for a range of object localization, object detection, and video tracking tasks.

Audio Classification

Lionbridge has 20 years of experience in transcribing, classifying, and evaluating audio in over 300 languages.

Text Annotation

Lionbridge's text annotation capabilities stretch from named entity recognition to chatbot training phrases, all supported by a customizable annotation platform and a crowd of language specialists.

Text Classification

Our annotation platform offers customizable options for classifying text across various categorization, moderation, and evaluation projects for machine learning.

Content Evaluation

We work with some of the world's biggest companies to improve content in 300 languages, including advertisements and search.

Our Data Annotation Tools

Develop specialized datasets through our fully customizable platform.

Why Lionbridge?



We undertake stringent quality checks to ensure that only accurate tags make it into your dataset.


Engage with our expert project managers to design a solution - or use our platform for total control of your project.


Even if you need secure annotation facilities or PII processes, we'll protect your data like it's our own.


1,000,000+ Contributors


300+ Languages



20+ Years of experience

Case Studies


Search Query Classification

We labeled over 200,000 English and Bahasa Indonesian search queries for Traveloka, one of south-east Asia's largest online travel companies. This helped them to build a multi-platform search engine.

Text Classification for ZAIZEN

We collected and labeled over 5,000 Q&A text samples for ZAIZEN, who used the data to build a personalized AI for use in everyday conversation.

Social Media Ad Review

We review over 1 million ads per month for one of the world's biggest social networking platforms. Employing 4,000 experience evaluators in 10 geographic markets, we're helping to maximize our client's campaign performance and boost their ad relevance across the globe.

Sentiment Analysis

We annotated the sentiment of over 20,000 texts in 14 languages for a multinational technology company. Discover how our data annotation services helped the client to improve and expand their sentiment analysis services.

Virtual Assistant Development

For an ongoing project with one of the world's largest technology corporations, our team edits and enhances the voice grammar framework of a virtual assistant which serves over 150 million users a month.

Annotation support for any workflow


Work with our annotators


Expert project management

Guideline and taxonomy development

Access to 1 million annotators

Customized quality assurance

Delivery in any file format


Equip your annotation team


Licensed annotation platform

Subscription-based seating plan

24/7 customer support

Free trial