The Text Annotation Tool to Train AI

Turn text into intelligence. Easy.

START NOW PDF logo; PDF Web-Based EditorDiscover our PDF annotation tool!
Web-Based Annotation Tool - tagtog


Get relevant insights from text, automatically

Discover patterns, identify challenges, realize solutions


  • > Analyze user feedback and design specific actions for improvement
  • > Enrich your unstructured text with metadata and make it searchable
  • > Find out bid opportunities in your industry
NLP Text Annotation Tool

Train your own AI

Generate training data for your own ML methods

tagtog is as its core a NLP text annotation tool. Create labeled datasets:

  • > Manage your team to annotate text manually (import pre-annotated data too)
  • > Leverage machine-learning models to work at scale and semi-supervised
  • > Find out biases in your data, and the quality of your annotations



  1. Import text

    Upload your own files (PDFs, plain text, CSVs, source code files, ...) or point to external resources like web URLs.

  2. Annotate manually or automatically

    Intuitively enrich text: annotate entities and disambiguate (e.g. company products, intents, etc.), classify documents and entities, draw relationships (e.g. diseases caused by mutations).

    tagtog learns from your annotations to annotate relevant information automatically. If you prefer, you can plug your own ML model in and use the feedback to train it.

    We have trained models ready to extract named entities automatically (e.g. vehicle parts, genetic mutations, etc.).

  3. Results

    Export the annotations in various formats using the API or the web interface. Use our search engine to discover actionable insights and make smarter decisions. That’s it!


  • Democratize Text Analytics
    No Coding or Data Engineering skills required

    Democratize Text Analytics. You don’t need to code or juggle with data to use tagtog. Use the intuitive web interface to create high-quality training data by just annotating.

  • Team Collaboration
    Team Collaboration and Quality management

    Invite other users to annotate text and create an annotated corpus. Define guidelines and roles at any moment. Track annotation progress and quality. You can distribute tasks automatically among users based on your quality requirements. More information

    Track quality and compare the performance of the different annotators using the inter-annotator agreement (IAA).

  • AI Web Editor Tool
    The best Text Annotation Tool

    Classify documents and entities manually or automatically. Annotate and disambiguate entities (e.g. company products, intents, etc. ), draw relations (e.g. diseases caused by mutations). More information

    Do you want to train your own algorithms? Import your predictions, correct them in the annotation tool, and feed them back.

  • Machine Learning Tool - Artificial Brain / Artificial Neural Network
    Machine Learning with people in the loop

    Plug your ML model and let your team of subject-matter experts provides feedback on the predictions for a continuous training. Improve quickly the quality of your training data and the accuracy of your machines. More information

  • Cloud and On-Premises symbol
    On our secure Cloud or OnPremises

    On the Cloud, there is nothing to install, no servers to worry about: start right now. On-premises, run tagtog as a docker image in your own infrastructure, SSO integration, Internet access is not required. In both cases, just use your favorite browser. More information

  • PDF Annotation Tool
    Multiple formats

    Work directly with your documents, not only plain text. Annotate natively over PDF or import the text from TXT files, HTML, CSV, PDF files, source code files, Markdown, etc.

  • Concept Search Tool; Finding Retrieval
    Multilingual support

    English, Spanish, Hindi, Bengali, French, Chinese, Japanese, Arabic, Swedish, Dutch, etc. Any language. Unicode support. Left to Right and Right to Left.

  • Quick generation of training data
    ML and dictionary annotations

    tagtog uses ML to learn from your annotations and generate similar annotations automatically. In addition, you can upload already-annotated documents or term dictionaries. Build high-quality training data in hours.

API Services API

Integrate tagtog within your existing workflow. Use the API to upload text, retrieve the results or manage folders. You can also use it to search across your text collection. More information

Folder organization Folders

Organize your text and documents in different folders and levels for a better organization. For example, separate test and production data.

Mergers and Acquisitions Overlapped annotations Overlapping entities

Make the most of your data, quick. Annotate overlapping entities or contained within others. Don't miss important information. More information

Concept Search Tool; Finding Retrieval Concept Search

Search in text collections not by keyword, but by concept (e.g. find all vehicle technical reports that are related to engine failures). More information

Entity Normalization Entity Normalization

Manage disambiguation. tagtog determines the identity of the annotations assigning unique ids from standard databases such as UniProt or Wikipedia.

You can also upload your own dictionaries to map the annotations to your unique internal references (e.g. product ref). More information

Big Text Annotation Big Text

Work with external text sources (e.g. PubMed) or your own files. Process millions of text items with ease.

Happy customers


We were looking for a way, not only of annotating aspects of the historical documents we work with in order to later extract information from these, but also to do so in an expedite manner and with people that is no expert in NLP or ML. We found tagtog online and it was love at first sight. It was the platform we were looking for.

Patricia Murrieta Flores
Co-Director of the Digital Humanities Hub, UK Lancaster University
Lancaster University

tagtog has been instrumental in our labeling efforts. We have a complex dataset and several sets of class labels. tagtog allowed our non-technical users to annotate large documents with ease, and allowed our data team to process their work using a sophisticated API. We are extremely satisfied with our investment.

Rachel Lomasky
Chief Data Officer, Wevo Inc.

tagtog allows us to have a fine-tuned control over tagging in a collaborative environment. AND the tagtog team is very responsive to our questions and new feature requests.

Beatrix Arendt
SCORE Program Manager, The Center for Open Science
Center for Open Science
PDF icon


PDF annotation example
  • Colorful annotations
    Annotate over the PDF

    Annotate directly over the native PDF layout, annotators love it! 💖

  • Loop symbol
    Train your models easily

    Import/Export annotations using text offsets or coordinates, tagtog gives you also the text contained in the PDF to facilitate the processing and generation of annotations.

  • Loop symbol
    Complete PDF viewer

    Navigate the document just by scrolling, zoom, pan (hand tool) or search across the document.

  • Colorful graph bars
    Annotate any text in the PDF

    Annotate text in figures, tables, pictures, etc.

It allowed us very easily to break down the different entities into selectable categories from the document, directly on PDF. Getting back both the text as well as its relative text positions, this was greatly helpful for us to create an NLP model with Machine Learning.

Eloi Pérez
Project Manager Innovation, KLB Group
Metrics and diagrams


Inter-Annotator Agremeent

Measure the quality of your labels

More information

Inter-annotator agreement matrix
Your datasets, under control

Track progress. Find and fix biases. Spot undersampled or oversampled data.

Entity distribution across the dataset
Label distribution across your dataset


Efficient text annotation tool to save time and costs Save time and costs

Creating training data is expensive; you want the right tool.

Flexible text annotation tool Flexible

Easily integrate it with your current workflow, software, and team.

Accessible text annotation tool Accessible

Engage subject-matter experts. Manage NLP projects efficiently.