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Companies using OCaml

“OCaml helps us to quickly adapt to changing market conditions, and go from prototypes to production systems with less effort ... Billions of dollars of transactions flow through our systems every day, so getting it right matters.” — Jane Street

Aesthetic Integration

Aesthetic Integration, United Kingdom

Aesthetic Integration (AI) is a financial technology startup based in the City of London. AI's patent-pending formal verification technology is revolutionising the safety, stability and transparency of global financial markets.


Ahrefs, Singapore, United States

Ahrefs develops custom distributed petabyte-scale storage and runs an internet-wide crawler to collect the index of the whole Web. On top of that the company is building various analytical services for end-users. OCaml is the main language of the Ahrefs backend, which is currently processing up to 6 billion pages a day. Ahrefs is a multinational team with roots from Ukraine and offices in Singapore and San Francisco.


American Museum of Natural History, United States

The Computational Sciences Department at the AMNH has been using OCaml for almost a decade in their software package POY for phylogenetic inference. See AMNH's GitHub page for more projects.


ANSSI, France

The ANSSI core missions are: to detect and react to cyber attacks, to prevent threats, to provide advice and support to governmental entities and operators of critical infrastructure, and to keep companies and the general public informed about information security threats. See ANSII's GitHub page for some of its OCaml software.


Arena, United States

Arena helps organizations hire the right people. We do that by applying big data and predictive analytics to the hiring process. This results in less turnover for our clients and less discrimination for individuals. We use OCaml for all of our backend development.

Be Sport

Be Sport, France

Be Sport's mission is to enhance the value that sport brings to our lives with appropriate use of digital and social media innovations. Be Sport is a 100% OCaml and OCsigen project, leveraged as the only building blocks to develop the platform.

Bloomberg L.P.

Bloomberg L.P., United States

Bloomberg, the global business and financial information and news leader, gives influential decision makers a critical edge by connecting them to a dynamic network of information, people and ideas. Bloomberg employs OCaml in an advanced financial derivatives risk management application delivered through its Bloomberg Professional service.


CACAOWEB, United Kingdom and Hong Kong

Cacaoweb is developing an application platform of a new kind. It runs on top of our peer-to-peer network, which happens to be one of the largest in the world. The capabilities of the platform are diverse and range from multimedia streaming to social communication, offline storage or data synchronisation. We design and implement massively distributed data stores, programming languages, runtime systems and parallel computation frameworks.


CEA, France

CEA is a French state company, member of the OCaml Consortium. It uses OCaml mainly to develop a platform dedicated to source-code analysis of C software, called Frama-C.


Citrix, United Kingdom

Citrix uses OCaml in XenServer, a world-class server virtualization system. Most components of XenServer are released as open source. The open-source XenServer toolstack components implemented in OCaml are bundled in the XS-Opam repository on GitHub.

As of summer 2018, Citrix in Cambridge UK is hiring software engineers passionate about functional programming and OCaml in particular.

Coherent Graphics

Coherent Graphics Ltd, United Kindgom

Coherent Graphics is a developer of both server tools and desktop software for the processing of PDF documents. We use OCaml as a general-purpose high level language, chosen for its expressiveness and speed.


Cryptosense, France

Based in Paris, France, Cryptosense creates security analysis software with a particular focus on cryptographic systems. A spin-off of the institute for computer science research (Inria), Cryptosense’s founders combine more than 40 years experience in research and industry. Cryptosense provides its solutions to an international clientèle in particular in the financial, industrial and government sectors.


Dassault Systèmes, France

Dassault Systèmes, the 3DEXPERIENCE Company, provides businesses and people with virtual universes to imagine sustainable innovations.

Dernier Cri

Dernier Cri, France

Dernier Cri is a French company based in Lille and Paris using functional programming to develop web and mobile applications. OCaml is principally used to develop internal tools.

Digirati dba Hostnet

Digirati dba Hostnet, Brazil

Digirati dba Hostnet is a web hosting company. We use OCaml mostly for internal systems programming and infrastructure services. We have also contributed to the community by releasing a few open source OCaml libraries.

Docker, Inc.

Docker, United States

Docker provides an integrated technology suite that enables development and IT operations teams to build, ship, and run distributed applications anywhere. Their native applications for Mac and Windows, use OCaml code taken from the MirageOS library operating system project.

Esterel Technologies

Esterel Technologies, France

Esterel Technologies is a leading provider of critical systems and software development solutions for the aerospace, defense, rail transportation, nuclear, and industrial and automotive domains.


Facebook, United States

Facebook has built a number of major development tools using OCaml. Hack is a compiler for a variant of PHP that aims to reconcile the fast development cycle of PHP with the discipline provided by static typing. Flow is a similar project that provides static type checking for Javascript. Both systems are highly responsive, parallel programs that can incorporate source code changes in real time. Pfff is a set of tools for code analysis, visualizations, and style-preserving source transformations, written in OCaml, but supporting many languages.


Fasoo, Korea

Fasoo uses OCaml to develop a static analysis tool.

Flying Frog

Flying Frog Consultancy, United Kindgom

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.


ForAllSecure, United States

ForAllSecure's mission is to test the world's software and provide actionable information to our customers. We have started with Linux. Our mission with Linux is to test all programs in current distributions, such as Debian, Ubuntu, and Red Hat. With time, we will cover other platforms, such as Mac, Windows, and mobile. In the meantime, we promise to do one thing well.


Framtidsforum I&M, Sweden

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.


Functori, France

Functori is a R&D company created by experienced engineers in programming languages (particularly OCaml), formal verification (automated reasoning, model checking, ...), and blockchain technology (core, smart contracts and applications development). In addition to contributing tools and libraries in OCaml and for the OCaml community, we are participating in the development of the Tezos blockchain in various ways: (1) core development, (2) building open-source tooling and libraries for the community (like indexers/crawlers, libraries to interact with the Tezos blockchain, etc.), (3) participating in the development of innovative projects for our clients, (4) auditing code for our clients, (5) consulting and training. Functori was founded in 2021 and is based in Paris (France), with people working remotely all around the world.


Galois, United States

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.


Incubaid, Belgium

Incubaid has developed Arakoon, a distributed key-value store that guarantees consistency above anything else. We created Arakoon due to a lack of existing solutions fitting our requirements, and is available as Open Source software.


Issuu, Denmark

Issuu is a digital publishing platform delivering exceptional reading experiences of magazines, catalogues, and newspapers. Each month Issuu serves over 6 billion page views and 60 million users through their worldwide network. OCaml is used as part of the server-side systems, platforms, and web applications. The backend team is relatively small and the simplicity and scalability of both systems and processes are of vital importance.

Jane Street

Jane Street, United States, United Kingdom, Hong Kong

Jane Street is a quantitative 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. They're the largest commercial user of OCaml, using it for everything from research tools to trading systems to systems infrastructure to accounting systems. Jane Street has over 400 OCaml programmers and over 15 million lines of OCaml, powering a technology platform that trades billions of dollars every day. Half a million lines of their code are released open source, and they've created key parts of the open-source OCaml ecosystem, like Dune. You can learn more by checking out their tech blog.


LexiFi, France

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.


Kong, USA

Kong makes it easy to distribute, monetize, manage and consume cloud APIs. Mashape is building a world-class marketplace for cloud APIs driven by a passionate community of developers from all over the world as well as enterprise API management and analytics products. We use OCaml in our APIAnalytics product — as part of a mission-critical, lightweight HTTP proxy.

Wolfram MathCore

Wolfram MathCore, Sweden

Wolfram MathCore uses OCaml to implement its SystemModeler kernel. The kernel's main function is to translate models defined in the Modelica language into executable simulation code. This involves parsing and transforming Modelica code, mathematical processing of equations, code generation of C/C++ simulation code, and numerical runtime computations.

Matrix Lead

Matrix Lead, France and China

Matrix Lead provides professionals and companies with leading technologies and solutions for spreadsheets. We create a range of software to help users better build, verify, optimize and manage their spreadsheets. Our flagship product 10 Studio is a Microsoft Excel add-in that combines our several advanced tools, such as formula editor and spreadsheet verificator. The kernel of our tools is an analyzer that analyzes different properties of spreadsheets (including formulas and VBA macros) especially by abstract interpretation-based static analysis. It was initially developed in the Antiques team of Inria and written in OCaml. Then, we wrap web or .NET languages around the analyzer to make ready-to-use tools.


MEDIT, France

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-modeling packages.

Mount Sinai

Mount Sinai, United States

The Hammer Lab at Mount Sinai develops and uses Ketrew for managing complex bioinformatics workflows. Ketrew includes an embedded domain-specific language to simplify the specification of workflows and an engine for the execution of workflows. Ketrew can be run as a command-line application or as a service.

Mr. Number

Mr. Number, United States

Mr. Number started as a Silicon Valley startup and developed the Mr. Number app for call blocking, later acquired by WhitePages. OCaml is used on the server-side as the glue between the various third-party components and services.


MyLife, United States

MyLife has developed 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.

Narrow Gate Logic

Narrow Gate Logic, Poland

Narrow Gate Logic is a company using the OCaml language in business and non-business applications.

Nomadic Labs

Nomadic Labs, Paris, France

Nomadic Labs houses a team focused on Research and Development. Our core competencies are in programming language theory and practice, distributed systems, and formal verification. Nomadic Labs focuses on contributing to the development of the Tezos core software, including the smart-contract language, Michelson. Tezos infrastructure is entirely implemented in OCaml. It strongly relies on OCaml efficiency and expressivity. For instance, Michelson smart contracts are represented using OCaml GADTs to prevent many runtime errors from happening. Safety and correctness are critical for a blockchain and we are glad that the OCaml type system allows for a form of a lightweight formal method that can be used on a daily basis.


OCamlPro, France

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 expertise, tools and libraries long-term support, and specific developments to their applicative domains.

PRUDENT Technologies

PRUDENT Technologies and Consulting, Inc., United States

Prudent Consulting offers IT solutions to large and mid-sized organizations by combining industry experience and technology expertise to help our customers achieve business goals with speed, agility, and great impact.


Psellos, United States

Psellos is a small group of computer scientists who became intrigued by the idea of coding iOS apps in OCaml. It has worked out better than we expected (you can buy our apps in the iTunes App Store), and at least one other company sells apps built with our tools. Our most recent iOS cross compiler is derived from OCaml 4.00.0.


r2c, California, United States

r2c is a VC-funded security company headquartered in San Francisco and distributed worldwide. The main product as of 2021 is Semgrep, an open-source, syntax-aware grep that supports many languages. OCaml is used extensively for parsing and analyzing source code.

Semgrep was originally open-sourced at Facebook and its roots lie in the Linux refactoring tool, Coccinelle. r2c continues Semgrep’s development and is hiring software engineers who specialize in program analysis.


Sakhalin, United States

Sakhalin develops marine charting apps for Apple iPads and iPhones. The full-featured apps display marine charts, GPS and onboard sensor data, Automatic Identification System, weather data, anchor monitoring, etc. The apps have a wide range of users, from occasional recreational boaters to professional river/harbor pilots that board large freighters. They are free to download and try (with a paid upgrade to enable all features). They are written almost entirely in Ocaml with a minor amount of glue to interface with IOS APIs. Ocaml was chosen because it (1) enables the rapid development of extremely reliable and high-performance software, (2) is a mature stable platform, and (3) has a wide range of libraries. It was made possible by the great work done by Psellos in porting OCaml to the Apple iOS platform. Feel free to contact Sakhalin if you have any questions about using OCaml on iOS.

Shiro Games

Shiro Games, France

Shiro Games is developing games using Haxe, a language built with a compiler written in OCaml.


Sleekersoft P/L, Australia

Specialises in functional programming software development, consultation, and training.


Solvuu, United States

Solvuu's software allows users to store big and small data sets, share the data with collaborators, execute computationally intensive algorithms and workflows, and visualize results. Its initial focus is on genomics data, which has important implications for healthcare, agriculture, and fundamental research. Virtually all of Solvuu's software stack is implemented in OCaml.

Studio Associato 4Sigma

Studio Associato 4Sigma, Italy

4Sigma is a small firm making websites and some interesting web applications. OCaml is not the main language used but it is used here and there, particularly in a small server that is a key component of a service we offer our customers.


Tarides, France

We are building and maintaining open-source infrastructure tools in OCaml: (1) MirageOS, the most advanced unikernel project, where we build sandboxes, network and storage protocol implementations as libraries, so we can link them to our applications to run them without the need of an underlying operating system; (2) Irmin, a Git-like datastore, which allows us to create fully auditable distributed systems which can work offline and be synced when needed; and (3) OCaml development tools (build system, code linters, documentation generators, etc), to make us more efficient. Tarides was founded in early 2018 and is mainly based in Paris, France (remote work is possible).


TrustInSoft, France

TrustInSoft is a company that changes the rules in cybersecurity. TrustInSoft is the software publisher of the software analysis Frama-C platform. Our motto is simple: make the formal methods accessible to the majority of software developers.

Zeo Agency

Zeo Agency, London

Zeo is a digital marketing company focused on helping companies to do better in SEO. Due to the nature of our business, we manage billions of lines in our database & create insights by using this data. To utilize our needs effectively, we use OCaml in our data crawling & processing part.


The appearance of a company's name here does not necessarily imply endorsement by that company of OCaml or of the descriptions provided here. Company representatives should contact us to have information about their company removed, modified, or added.