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May 3, 2022

Ultimate list of free and paid best image annotation tools

May 3, 2022

What are annotation tools and where are they used? 

Judging by the current rate of data creation, data annotation is no easy task, and the ability of the algorithms we use today to perform effectively depends on data annotation. Computers can't interprete situations or provide context the way humans can so data annotation was birthed to make those connections. It is the human-in-the-loop approach of labeling content like text and audiovisuals (images and video) so they can be correctly recognized by ML models and used to make accurate predictions. 

What is image annotation 

Image annotation in machine learning and deep learning can be defined as the process of annotating an image with labels, usually involving a human-in-the-loop approach and the occasional computer assisted help. It involves classifying an image using annotation tools, to show the data features you want your model to recognize on its own and it is mainly done so the system will be able to recognize objects with greater precision. This is usually done with datasets that are used to train ML algorithms. 

Difference between image annotation and labelling 

Image labeling and image annotation are phrases used interchangeably when trying to describe the art of classifying or identifying images for training machine learning algorithms. Both processes need to be executed with great precision and clarity with their major difference being that annotation helps the system recognize relevant data through computer vision whereas labeling is used for training advanced algorithms to recognize patterns in future so it'll be able to make decisions on its own.

3 free image annotation tools

1. Isahit lab:
This is an image annotation tools that is extremely easy to use which allows you to annotate an unlimited number of images for free. It also allows you to invite teams and users to assist you on your annotation projects. Isahit spent years developing this intuitive annotation tool and were able to draw from their experience in handling labeling projects through their outsourcing platform.

2. CVAT:
CVAT is an acronym which stands for Computer Vision Annotation Tool and it is a free open source annotation tool which is developed by Intel and it also supports video annotation. It also has a user-friendly interface which makes annotating easier. To start using CVAT,  you'll need to create an account first on after which you'll be given access to the tool and you can start annotating your data.

3. Labelme:
Labelme is an open source annotation tool that you could use to process image datasets. A key feature to be noted on the tool is the “File List” option on the bottom right. This could come in handy when you have a lot of images to annotate, because it reduces the chances of you missing any images. The only disadvantage of labelme is that your file can only be saved in JSON format. 

3 paid image annotation tools

1. V7:
V7 is an automated annotation tool that combines dataset management, image and video annotation, and auto machine learning model training to complete annotation tasks. The platform enables teams to store, manage, annotate, and automate their data annotation workflows in videos, images, medical data and other formats. Price options start from $150.

2. Labelbox:
Labelbox offers AI-powered labeling tools, labeling automation, human workforce, data management, among other services along with a powerful API for integration. The platform offers a superpixel coloring option for semantic segmentation and a friendly user interface.

3. Data loop:
This is an all-in-one cloud-based annotation platform with embedded tools and automation capable of producing high-quality datasets. The platform makes provision for the entire AI lifecycle including annotation, model evaluation, and model improvement by using a human in the loop approach. It also offers tools for basic recognition tasks like detection, classification, key points, and segmentation while also supporting both image and video data. It also has advanced team workflows with streamlined data indexing and video support.

Key criteria for reviewing image annotation tools

When doing image annotation, it is very important that you choose a very good tool as it will directly affect the quality of your processed work. There are certain criteria you should take into consideration such as functionality, efficiency, formatting, application and price to be able to find a tool that adequately fits your needs. There are many image annotation tools out there and you have to do your research carefully to make sure you choose a tool that works best for you and your project. 

Outsourcing image labeling - The solution for large-scale annotation projects

If you have a large volume of images that need to be labeled, outsourcing can be a smart solution. Companies like isahit offer image labeling services that not only provide you with the annotation tool, but also a trained and qualified workforce to annotate your data accurately and efficiently.

With isahit, you can trust that your annotation project is in good hands. Their diverse and qualified workforce is committed to providing you with high-quality labeled data, ensuring that your project is completed on time and to your satisfaction. By outsourcing your image labeling needs, you can save time and resources, and focus on other important aspects of your project.

Each unique project has a specific need when it comes to annotation tools. One might need either an image annotation tool, a text annotation tool, a video annotation tool or some combination of the above. With so many tools to choose from, finding the right fit can be a frustrating process. Not to worry though- we’ve rounded up a master list of the best open source annotation tools in 2022. Keep reading to find the best annotation tool for your unique needs!

Best Image and Video Annotators


The Computer Vision Annotation Tool is a powerful and efficient image and video annotator. It is open source and web based, and though its user interface is not very intuitive, amateurs and professionals will be able to take advantage of it after getting over the learning curvet.

Key Features:

  • Web based
  • Maintained by Intel
  • Annotation is semi-automatic


  • Web based 
  • Third Party Integrations
  • Easy to deploy on local networks
  • Tutorials available online
  • Supports a variety of file types


  • No customer support
  • CVAT has to be maintained as it scales
  • No pdf file support
  • Learning curve; the UI may take several days to master

Source code-


Labelimg has been around for over 5 years, and is one of the popular, dependable tools for graphic image labelling on the web. It has a simple interface which is also pretty intuitive, making it pretty easy to work with.

Key Features

  • Written in Python
  • Graphical Interface is in QT
  • Annotations are saved and exported as XML files
  • Needs to be installed locally


  • Can be used offline for added security
  • Simple, intuitive interface, even for beginners


  • Default version offers only one annotation type (bounding box)
  • Needs to be installed locally

Does not offer video annotation

Source code-


LabelMe is an open source dataset of digital images with annotations. Free to use, it was created by the MIT Computer Science and Artificial Intelligence Laboratory in 2008, and users are allowed to contribute to the library. It has a voluminous library, described by some as canonical.

Key Features

  • Made by MIT Computer Science and Artificial Intelligence Laboratory


  • Six different types of annotations offered
  • Customizable UI
  • Can be used both online and offline


  • Files can only be exported and saved in JSON format
  • No program management capabilities
  • Low level of precision

Source code-


OpenLabeling is a sturdy tool for both image and video annotation in computer vision applications Created by João Cartucho, this tool was licensed in 2018.

Key Features

  • Runs in Python
  • Features a pre-trained model 


  • Multiple annotation formats are available, for example PascalVOC and YOLODarknet
  • Deep Learning feature available


  • Both Python and OpenCV have to be downloaded to use this tool

Source code-

Best Text Annotation Tools


Developed to annotate chunks of text, YEDDA is able to work in many languages including English and Chinese. Text, symbols and even emojis can be accurately annotated by this super tool.

Yedda also supports shortcut annotation which increases efficiency in annotating text by hand.

Key Features

  • Runs in Python, requires Python preinstallation
  • Supports shortcut annotation


  • Collaborative capability
  • User Interfaces both for administrators and annotators


  • Users complain of a few bugs while using this tool
  • Not available offline

Source code


Another popular open source text annotator, ML-Annotate is one of the first choices for many when it comes to text annotation. Developed by 

Key Features

  • Runs on Python


  • Administrative users can be added
  • UI is completely customizable, with instructions for making modifications provided
  • Supports multi-class,multi-label and binary labelling
  • Can be used offline


  • Data library not included.

Source code

We hope this was helpful! If you’re still undecided, you can check out our table below for the summarised version of all the info above.

Image and video annotation comparative table

Your AI project's success or failure will be determined by the data annotation tools you employ to enrich your data for training and deploying machine learning models. 

What is data annotation?

The process of labeling data to show the results you want your machine learning model to forecast is called data annotation in machine learning. You're marking up a dataset with the qualities you want your machine learning system to learn to recognize by labeling, tagging, transcribing, or processing it. 

What is a data annotation tool?

A data annotation tool is a solution that can be used to annotate industrial-grade training data for machine learning. It can be cloud-based, on-premise, or containerized. The following are essential features of data annotation software: Text, image, video, audio, time-series, and sensor data are all examples of data types that can be annotated with them. They support 2-D, 3-D, video, audio, transcription, and text annotation.

Important features of a data annotation tool.

1. Dataset management:

Annotation begins and ends with a thorough understanding of how to manage the dataset you're going to annotate. You must confirm that the tool you are contemplating will really import and support the large volume of data and file formats you need to label as a crucial element of your process. Datasets can be searched, filtered, sorted, cloned, and merged using this method.

2. Data quality control:

The quality of your data will determine the performance of your machine learning and AI models. Quality control (QC) and verification processes can be made easier with data annotation tools. Ideally, the tool will include quality control as part of the annotation process.

3. Data security:

Whether you're annotating sensitive protected personal information or your own valuable intellectual property, you'll want to keep your data secure. Tools should restrict data downloads and limit an annotator's viewing rights to data not assigned to them.

Tips for selecting a data annotation tool

1. Figure out what you're going to use it for: First and foremost, the type of data you wish to annotate as well as your work procedures will influence your tool selection. Text, image, and video can all be labeled with tools. Video labeling is possible with some image labeling software. As a result, select a tool based on your objectives.

2. What are the requirements for quality control?

Your data annotation tool should also take into account how you wish to measure and control quality. Quality control (QC) elements are included into many commercially accessible tools, and they can review, provide feedback, and correct activities.

3. Workforce training: Whether your data is annotated by employees or contractors, crowdsourcing, or an outsourcing provider, your workforce will need access to and training to use your data annotation tool, with specific instructions particular to your use case.

3 free data annotation tools

1. Computer Vision Annotation Tool (CVAT):

CVAT is a web-based, free, open-source annotation tool that can be used to annotate image and video data for computer vision algorithms.

It has a dashboard with a list of annotation projects and tasks, as well as interpolation of shapes between keyframes, shortcuts for the most important activities, and a dashboard with a list of annotation projects and tasks. The primary tasks of supervised machine learning are supported by CVAT. Object identification, image classification, and image segmentation are all things that can be done with images.

2. Kili Technology :

Kili Technology is a labeling platform for training data. Kili Technology offers one tool to label, find and fix issues, simplify DataOps, and dramatically accelerate the build of reliable AI.

Kili Technology offers 3 plans for these customers, a free offer limited to 5 users and 1000 annotations per month and two paid plans from 20 000 to 500 000 annotations included as well as the addition of an external work force. Kili Technology and isahit are main partners, Kili is isahit's main technological partner, and conversely, isahit provides Kili with a diversified, competent and committed workforce.

3. Labelstudio :

Labelsudio is a flexible data labeling tool for all data types. Prepare training data for computer vision, natural language processing, speech, voice, and video models.

3 paid data annotation tools

1. Labelbox

Labelbox's training data platform is designed to assist you in improving your training data iteration loop. It's built around three main pillars: the ability to annotate data, diagnose model performance, and prioritize tasks based on your findings. By using the latest in labeling automation, you can reduce annotation costs by 50-80%, iterate 3 times quicker on your AI data to construct more performant models, and work more efficiently with data scientists, labelers, and domain experts with Labelbox.

2. Scale

Scale is a data platform to annotate enormous amounts of 3D sensor, picture, and video data. This data annotation tool supports several data formats and can be used for a range of computer vision applications, such as object detection, classification, and text recognition. Its advanced LiDAR, image, video and NLP annotation APIs allow machine learning teams at companiesto focus on building differentiated models vs. labeling data.

3. V7

V7 is an automated annotation platform that combines dataset management, image and video annotation, and autoML model training to perform labeling tasks automatically. V7 allows teams to store, manage, annotate, and automate data annotation operations in pictures, video, medical data, microscopy images, PDF and document processing, and other formats.

Want to explore more tools? We share with you this curated list of data labeling tools !

Scale your digital annotation projects with a highly trained workforce

In-house annotation can limit you in terms of volume and create some bias in annotation.

Today, data labeling companies can make all the difference in the training of your algorithms: by training and coaching a diverse, competent and committed workforce supported and challenged by a project team that follows the quality of the annotations and monitors your projects daily.

Moreover, outsourcing your annotations can also be an opportunity for the company to generate a positive social impact among the annotators! Isahit is the first and only player in the industry to offer an agile, socially responsible data labeling service powered by human intelligence.

They build, train and deploy a customized and diverse workforce on their clients' digital projects: data labeling, algorithm training, etc. while generating a real positive impact with their workforce: an additional income 5x higher than the average in their country, free trainings and a caring community to lean on. BCorp certified since 2021, isahit is revolutionizing the world of data tagging and outsourcing by making it ethical.


Your data annotation tool's sophistication and features have an impact on how you and your data team plan workflow, quality control, and many other areas of your data work. A tool that does not address your workforce and processes will cost you time and efficiency in the form of workarounds for features you wish were inherent to the product. Before choosing your tool, be sure to check the tool's functionality and define your needs! And if you want to scale up your annotation projects, use an external, competent and committed workforce (with ethics)!

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