England
- Acunu
  Acunu is writing, from the ground-up, a Storage and Analytics Platform for Massive Data.
- Citrix
- Flying Frog Consultancy
  Flying Frog Consultancy Ltd. consult and write books and software on the use of OCaml in the context of scientific computing. OCaml excels in the niche of intrinsically complicated programs between large-scale, array-based programs written in languages such as HPF and small-scale, graphical programs written in languages such as Mathematica.
- Merjis
  Merjis Ltd. work on improving website return on investment by having a mix of good marketing and excellent understanding of the technology. We use OCaml because it represents the best of breed technology to use when building websites.
France
- Dassault Systèmes
- Esterel Technologies
- LexiFi
  LexiFi is an innovative provider of software applications and infrastructure technology for the capital markets industry. LexiFi Apropos is powered by an original formalism for describing financial contracts, the result of a long-term research and development effort.
- MEDIT
  MEDIT develops SuMo, an advanced bioinformatic system for the analysis of protein 3D structures and the identification of drug-design targets. SuMo is written entirely in OCaml and provides interfaces to several commercial molecular-modelling packages.
- Motion-Twin
  Motion-Twin is building web-based Flash video games for several web sites such as Frutiparc and Prizee and KadoKado. Because controlling the technology is critical for us, we're developing a lot of in-house tools using OCaml to gain development time and stability advandages over competitors. Using OCaml enables us to quickly develop robust software that we need to build our games.
- MLstate
  MLstate is the creator of Opa: an open-source web development platform. It consists of a new programming language, a new web server, a new database and a new distributed execution engine, all of them tightly integrated to provide a great experience for web developers. Opa is concise, simple, concurrent, dynamically secure and secure out of the box. It is written mainly in OCaml and uses OCaml as an intermediate language for compilation.
- OCamlPro
  OCamlPro develops and maintains a development environment for the OCaml language. They provide services for companies deciding to use OCaml. Among these services: trainings, necessary expertises, tools and libraries long-term support, and specific developments to their applicative domains.
- RunOrg
Japan
- IT Planning
  We use Ocaml for some kind of enterprise systems (i.e. production control, portfolio risk management and web services).
Poland
- Narrow Gate Logic
  Narrow Gate Logic is a company using Ocaml language in business and non-business applications.
Sweden
- Framtidsforum I&M
  Framtidsforum I&M sells ExcelEverywhere, which creates web pages that look and function the same as your MS Excel spreadsheet. JavaScript is used for calculation. Supports 140 Excel-functions. Typically used for expense report, survey, order forms, reservation forms, employment application, financial advisor, ROI. There are also versions that generate ASP, ASP.NET and JSP/Java code. The compiler is written using Ocaml.
Uganda
- Digital Solutions
  General programming, with wide base and experience in Mobile Telephony programming and web application development.
United States
- Galois
  Galois has developed a domain specific declarative language for cryptographic algorithms. One of our research compilers is written in OCaml and makes very extensive use of camlp4.
- JaneStreet
  Jane Street is a quantitative proprietary trading firm that operates around the clock and around the globe. They bring a deep understanding of markets, a scientific approach, and innovative technology to bear on the problem of trading profitably in the world's highly competitive financial markets.
  Jane Street is perhaps the largest commercial user of OCaml, and has attracted a very strong team of functional programmers. They use OCaml for everything, from research infrastructure to trading systems to operations and accounting systems. Jane Street has over 50 OCaml programmers and over a million lines of OCaml, powering a technology platform that trades billions of dollars every day.
- MrNumber (formerly Skydeck)
- MyLife (formerly Wink)
  MyLife has developped a powerful people search tool that will empower those in need to find anyone, regardless of years past and the life that was built in between.
- Psellos
- PRUDENT Technologies and Consulting, Inc.