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OPAM is a source-based package manager for OCaml. It supports multiple simultaneous compiler installations, flexible package constraints, and a Git-friendly development workflow.
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Latest commit ecc8e2d @AltGr AltGr Merge pull request #2363 from OCamlPro/format-preserving-printer
Implement a printer that preserves (some) formatting
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OPAM - A package manager for OCaml

OPAM is a source-based package manager for OCaml. It supports multiple simultaneous compiler installations, flexible package constraints, and a Git-friendly development workflow.

OPAM was created and is maintained by OCamlPro.

To get started, checkout the Install and Usage guides.

Compiling this repo

  • Make sure you have OCaml and GNU make installed. If you don't have a recent enough version of OCaml (>= 3.12.1) at hand, see the next section.
  • Run ./configure
  • Run make lib-ext as advertised by ./configure if you don't have the dependencies installed. This will locally take care of all OCaml dependencies for you (downloading them, unless you used the inclusive archive we provide for each release).
  • Run make
  • Run make install

This is all you need for installing and using opam, but if you want to use the opam-lib (to work on opam-related tools), you need to link it to installed libraries, rather than use make lib-ext which would cause conflicts. It's easier to already have a working opam installation in this case, so you can do it as a second step.

  • Make sure to have ocamlfind, ocamlgraph, cmdliner, jsonm, cudf, dose 3.2.2+opam and re >= 1.2.0 installed. Or run opam install opam-lib --deps-only if you already have a working instance. Re-run ./configure once done
  • Run make libinstall at the end

Compiling without OCaml

make cold is provided as a facility to compile OCaml, then bootstrap OPAM. You don't need need to run ./configure in that case, but you may specify CONFIGURE_ARGS if needed, e.g.:

make cold CONFIGURE_ARGS="--prefix ~/local"

NOTE: You'll still need GNU make.

Bug tracker

Have a bug or a feature request ? Please open an issue on our bug-tracker. Please search for existing issues before posting, and include the output of opam config report and any details that may help track down the issue.


User Manual

The main documentation entry point to OPAM is the user manual, available using opam --help. To get help for a specific command, use opam <command> --help.

Guides and Tutorials

A collection of guides and tutorials is available online. They are generated from the files in doc/pages.

API, Code Documentation and Developer Manual

A more thorough technical document describing OPAM and specifying the package description format is available in the developer manual. make doc will otherwise make the API documentation available under doc/.


Keep track of development and community news.

  • Have a question that's not a feature request or bug report? Ask on the mailing list.

  • Chat with fellow OPAMers on IRC. On the server, in the #ocaml or the #opam channel.


We welcome contributions ! Please use Github's pull-request mechanism against the master branch of the OPAM repository. If that's not an option for you, you can use git format-patch and email TODO.


The release cycle respects Semantic Versioning.

Related repositories

  • ocaml/opam-repository is the official repository for OPAM packages and compilers. A number of non-official repositories are also available on the interwebs, for instance on Github.
  • opam2web generates a collection of browsable HTML files for a given repository. It is used to generate
  • opam-rt is the regression framework for OPAM.
  • opam-publish is a tool to facilitate the creation, update and publication of OPAM packages.

Copyright and license

The version comparison function in src/core/ is part of the Dose library and Copyright 2011 Ralf Treinen.

All other code is:

Copyright 2012-2015 OCamlPro Copyright 2012 INRIA

All rights reserved. OPAM is distributed under the terms of the GNU Lesser General Public License version 3.0.

OPAM is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

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