What is Chordify?

Chordify is a free online music service – made for and by music enthusiasts – that transforms music from YouTube, Deezer, SoundCloud or your private collection, into chords. Our service automatically recognises chords from the audio signal, and aligns them to the music in a simple and intuitive player. Chordify is a cutting edge service that helps both novice and trained musicians to play the music they want to play, making state-of-the-art music technology available to the public at large.

Technology behind Chordify

We’ve done our best to make our website simple and easy to use, even though there is some complex technology behind Chordify. Our website is built using up to the minute web development techniques, like HTML5 audio etc.

Behind the scenes, we use the sonic annotator for extraction of audio features. More specifically, we extract the NNLS chroma features developed by Matthias Mauch using the Chordino VAMP plugin. These features describe the tonal content of a piece of music. Next, a Haskell program HarmTrace then takes these features and computes the chords. For this to happen, HarmTrace uses a model of Western tonal harmony to aid in the chord selection. At beat positions where the audio matches a particular chord well, this chord is used in the final transcription. However, where there is uncertainty about the sounding chords at a specific position in the song, the HarmTrace harmony model will select the correct chords based on the rules of tonal harmony.

Chordify fosters open-source software. Not only do we use open-source software packages like GHCPHPSoXsonic annotator and MongoDB, but we also give back a large share of the in-house developed technology to the music information retrieval research community via open-source software projects like HarmTrace and scientific publications.

Chordify could not have been realised without the support of Utrecht University.

The Chordify team

Bas de Haas  CEO \\ Founder
After Bas finished his PhD in computer science at Utrecht University in 2011, he brought together this team of music enthusiasts to create Chordify. Bas’ research focuses on music information retrieval, digital signal processing, and machine learning. Bas is passionate about music, playing guitar, new technologies, and entrepreneurship.

Dion ten Heggeler  CBDO \\ Founder
Dion is responsible for Chordify’s design and business development. Dion is an experienced communication designer with over a decade of business experience and a passion for discovering emerging music and musicians.

Gijs Bekenkamp  CMO \\ Founder
Gijs is the second half of the Chordify design team. He spent ten years of his life playing in a band with Bas. Alongside Dion, Gijs is responsible for Chordify’s design and communication.

Tijmen Ruizendaal  CTO \\ Founder
Tijmen plays drums in the band Niek Pronk and DJ HAGY. He’s responsible for the frontend of Chordify and works closely with both the backend guys and the designers.

Jeroen Bransen  Lead Backend Developer
Jeroen is responsible for the backend of Chordify, and programs mostly in Haskell. Before working at Chordify he obtained his PhD degree in the area of functional programming. Jeroen plays guitar and is a fan of the Dutch band Golden Earring.

Ilse Niessen  Online Marketeer

Robert Nabbe 
Customer Support

Ilse Bekkema 
Office Manager

Hendrik Vincent Koops 
Music Information Retrieval Researcher

Jonathan Driedger 
Music Information Researcher

Bart Laan
  Front-end Developer

Jorine Witte 
Head of Content

Teo Lazarov 
Copywriting & Public Relations

Pierre van de Velde 
Front-end Development

Pieter Nomden  Finance

Rob Wegter 
Copy Editing & Translations


We would be happy to hear from you. For our most frequently asked questions or suggestions, head over to our UserVoice page.

Chordify offices

Chordify B.V.
Boterdiep 63
9712 LK Groningen
The Netherlands

Utrecht Office
Boothstraat 2A
3512 BW Utrecht
The Netherlands

Policies and Terms

Diversity and anti-harassment policy
Terms and Conditions

By Chordify, latest update: