Fabrice Le Fessant

Voir ma Page Personnelle


  • CEO at Origin-Labs (2019-)
  • CTO at OCamlPro (2018-2019)
  • Scientific Advisor at OCamlPro (2011-2018)
  • Senior Researcher at INRIA (2003-2018)
  • Teaching Positions at Ecole Polytechnique (1996-2012)
  • Junior Researcher at Microsoft Research (2002-2003)


I have cofounded several companies:
  • Origin Labs (2019) is a company focused on the blockchain technology. It develops industrial and finance blockchain applications using cutting-edge technologies, with a focus on security and correctness. Origin Labs develops the Dune Network blockchain, a fork of the Tezos blockchain with multiple extensions for companies.
  • OCamlPro (2011) is a company focused on the OCaml programming language, and the use of formal methods for software verification. It develops applications, prototypes for startup, with a focus on security and correctness. For example, OCamlPro developed the prototype of the Tezos blockchain, the TzScan block explorer, the Optal language, the OPAM package manager, and many other open-source softwares (see the Timeline).
  • Peerple/MoveNPlay (2005) was my first startup, co-founded with Anh-Tuan Gai and Laurent Viennot. It started as a social network in peer-to-peer with privacy at heart. It was one of the first companies to create applications on jail-broken iPhones, before the creation of Apple Store.

Research and Publications

As a researcher, I had two domains of research:
  • Programming Languages, and especially the OCaml Programming Language.
  • Programming of Massively Distributed Systems , and especially Peer-to-Peer Systems.
Funnily, Blockchains put these two domains together.

Have a look at my complete List of Publications or on HAL (only the most recent ones).

Open-Source Software

I have developed quite a few open-source software projects.

  • Blockchain software: I am one the main developers of the Dune Network blockchain, of the Liquidity smart contract language, of the TzScan block explorer, and of the Dune app for Ledger hardwallets.
  • OCaml tooling I was one of the main developers of OCaml Memprof at OCamlPro, one of the best memory profilers for OCaml, I wrote ocp-build, a composable build system for OCaml with many features that were later provided by the Dune build system. I contributed many patches and proposition to the OCaml compiler, for example variables in or-patterns.
  • Mobile software: I wrote MNPlight in 2007, one of the first applications for jailbroken iPhones. MNPlight could synchronize many files with a computer, including emails, music and agenda.
  • Biology software: I wrote DNApack in 2005 with Behshad Behzadi, a compressor in OCaml for DNA sequences based on approximate duplicates and clever encoding.
  • Peer-to-peer software: I wrote MLDonkey in 2002, a multi-network peer-to-peer client. MLdonkey had about 50,000 users downloading files from Edonkey, Overnet, Gnutella, Direct-Connect or Soulseek.
  • Video software: I wrote LAMP (Linux Animation and Movie Player) in C++ in 2000. LAMP was a able to read multiple movie formats, and was one of the first DIVX players on Linux, before mplayer and vlc.
  • Unix software: I wrote GwML (a Generic Window Manager) in 1999, and Efuns (Emacs for Functions) in 1998, both in OCaml. GwML was a window manager configurable in OCaml, that was able to emulate the best features of Twm, TvTwm, Fvwm and Fvwm2. Efuns was an Emacs clone, configurable in OCaml. It included a full rewritting of the X11 library in OCaml, and modes for OCaml, C, TeX and Makefile. With lexers/parsers written with OCaml tools, it was very powerful to indent and colorize buffers.
  • Language software: I wrote JoCaml in 1997, an extension of OCaml with primitives from the Join-Calculus to easily program distributed applications.

Since 2010, I am part of the Steering Committee of the Open-Source Hub at Systematic.

In the past, I also got involved in some ICFP Programming Contest Teams: 2010, 2004 , 2001 , 2000 .


I got involved in the fight against anti-P2P laws in France in 2009. I wrote a document against HADOPI law that was cited by Mme Martine Billard in the French Assemblée Nationale. I was also interviewed by Mme Marland-Militello, for which I wrote a report.

I wrote a book on peer-to-peer for Eyrolles:

Le Peer-to-Peer

Pour essayer d'en finir avec la mauvaise réputation du peer-to-peer, j'ai publié un petit livre chez Eyrolles, dans la collection Connectez-moi (au prix très abordable de 5,90 euros), appelé "Le peer-to-peer: comprendre et utiliser". Dans cet ouvrage, j'essaie, à partir de mon expérience de créateur du projet MLdonkey, client peer-to-peer multi-réseau, d'expliquer un peu les fondements de cette techno, son utilisation actuelle à travers les logiciels d'échange de fichiers, mais aussi de messagerie et de téléphonie, ainsi que d'applications futures telles que la sauvegarde croisée de données. Le livre met en avant les logiciels libres sur les trois grands systèmes du moment (Linux, Mac OS X et Windows), en les distinguant bien des autres freewares avec lesquels ils sont bien trop souvent confondus, y compris par nos parlementaires.

Contact Information

Fabrice Le Fessant
OCamlPro, 21 rue de Chatillon
F-75014, Paris

GPG Public Key (E940 4D20 3914 769A 9664 7192 6524 676E BACD 7D55)
SSH DSA Public Key
Villa Fakarava à Trégastel