List of Open-Source Annotation Tools for Machine Learning Research

There are quite many annotation tools out there, however it seems like each and every tool comes with their unique disadvantages. Anyhow, here is a list of tools I came across. And yes, I only post tools which are open-source. I highly recommend to write your own project-specific annotation tool that automate away as much as possible. This may take a week or two (or three ;)) but is much more efficient.

last update of this list: 2023-01-20


  • aubio
    • simple annotation tool to label waveforms. contains some processing capabilities as well
  • audino
    • transcription and labelling for audio data
  • audio-annotator
    • web interface for audio annotation
  • audio-labeler
    • web-based annotation tools for waveforms
  • EchoML
    • web-based annotation tool for audio files
  • Labeltool
    • annotation for sets of audio
  • Praat
    • Praat: doing phonetics by computer. Larger framework for phonetics that has some annotation capabilities

Computer Vision

General Purpose

  • label-studio
    • general purpose annotation tool that supports labeling for audio, computer vision and NLP applications with an integrated ML backend for active learning

Point Clouds

Source code



Scroll to Top