doccano is a web-based annotation tool for creating labeled text data. Machine learning practitioners use it to prepare datasets for text classification, sequence labeling and sequence-to-sequence tasks such as sentiment analysis, named entity recognition and summarization.

Features

• Collaborative annotation for teams
• Multi-language support, emoji support and a dark theme
• Mobile-friendly interface
• A RESTful API for automating projects

The workflow is simple: create a project, upload your data and start labeling. According to the authors, a dataset can be built in hours.