# Standalone Ocaml Runtime Package / Source code **URL:** \ **Category:** Ecosystem\ **Tags:** runtime, opam\ **Created:** [April 11, 2025, 5:03pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480 "2025-04-11T17:03:04Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![ferdv](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/ferdv/32/5902_2.png) [@ferdv](https://discuss.ocaml.org/u/ferdv)\ **Post date:** [April 11, 2025, 5:03pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/1 "2025-04-11T17:03:04Z")
TL;DR Is there a (preferably straightforward way) of installing the OCaml runtime, separately from the compilers and other tools in the base OCaml distribution? Hi all, I’m coming back to OCaml after almost a decade away and I’m thinking about porting some of my utilities from various “lowest common denominator languages” (i.e., mostly Bash and Python) to OCaml. I’m wondering about the best way to distribute these to colleagues who are not OCaml users. I’ve seen discussions about the obvious portability of the bytecode combined with how `ocamlrun` is easily compilable with a standard C compiler. However, in practice, I haven’t found anything on distributing or installing just the interpreter and runtime, separately from the rest of the tooling in the OCaml repository. I also haven’t found any Opam package (so far) that would appear to only include the runtime and standard library for running OCaml programs. How are people distributing their programs, at least to the various POSIX-conforming platforms, other than targeting them directly with native code? If there isn’t currently anything in place, would there be interest in extracting the bytecode runtime into a separate Opam (potentially, Homebrew/apt/Nix/_whatever_) package? Thanks, Ferd ---
**Author:** ![Frederic\_Loyer](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/frederic_loyer/32/3472_2.png) [@Frederic\_Loyer](https://discuss.ocaml.org/u/Frederic_Loyer)\ **Post date:** [April 17, 2025, 5:08pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/2 "2025-04-17T17:08:06Z")
Just compile your program with ocamlopt… it makes a native executable which doesn’t need ocamlrun or whatever else. That’s remind me a Python program I wasn’t able to share with someone… I have translated it in OCaml… then no issue. ---
**Author:** ![cvine](https://avatars.discourse-cdn.com/v4/letter/c/90db22/32.png) [@cvine](https://discuss.ocaml.org/u/cvine)\ **Post date:** [April 17, 2025, 6:04pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/3 "2025-04-17T18:04:25Z")
If you want to distribute bytecode executables rather than native executables (why?), the `ocamlc` `'-custom'` option may do what you want. It will link the runtime into the executable to allow separate distribution. The manual says this: > -custom: > Link in “custom runtime” mode. In the default linking mode, the linker produces bytecode that is intended to be executed with the shared runtime system, ocamlrun. In the custom runtime mode, the linker produces an output file that contains both the runtime system and the bytecode for the program. The resulting file is larger, but it can be executed directly, even if the ocamlrun command is not installed. Moreover, the “custom runtime” mode enables static linking of OCaml code with user-defined C functions, as described in chapter 22. When compiling a bytecode executable, I believe dune uses custom mode by default. Obviously this won’t help if you want to distribute your programs to colleagues in source code form as a script. Your colleagues would I think then need a compiler. ---
**Author:** ![mobileink](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mobileink/32/3295_2.png) [@mobileink](https://discuss.ocaml.org/u/mobileink)\ **Post date:** [April 18, 2025, 12:51am UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/4 "2025-04-18T00:51:56Z")
> [@ferdv](#): > > How are people distributing their programs, at least to the various POSIX-conforming platforms, _other than targeting them directly with native code_ Obviously, recommending ocamopt, -custom etc. is not responsive. Some kind of “ocamlrun only” package might be useful, but you might run into versioning issues - I’m not sure how portable bytecode is across complier versions. Plus the only diff is that bytecode stuff does not need a c compiler - but you’d need a c compiler anyway to build ocamlrun.My guess is that the easiest thing to do ATM would be to recommend installation of the SDK without opam. That would give your colleagues the ocamlrun they need to run your stuff. Other stuff too but they can ignore that. The alternative would be to distribute ocamlrun binaries. That seems reasonable to me. ---
**Author:** ![cvine](https://avatars.discourse-cdn.com/v4/letter/c/90db22/32.png) [@cvine](https://discuss.ocaml.org/u/cvine)\ **Post date:** [April 18, 2025, 8:36am UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/5 "2025-04-18T08:36:08Z")
> [@mobileink](#): > > The alternative would be to distribute ocamlrun binaries. That seems reasonable to me. That is of course in effect what the (not responsive) `-custom` option does, except that linking with `-custom` builds the runtime system into the bytecode executable. The advantage of that is that it avoids versioning issues. ---
**Author:** ![mobileink](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mobileink/32/3295_2.png) [@mobileink](https://discuss.ocaml.org/u/mobileink)\ **Post date:** [April 18, 2025, 12:12pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/6 "2025-04-18T12:12:33Z")
> [@cvine](#): > > That is of course in effect what the (not responsive) `-custom` option does, ocamlrun can run any bytecode executable. A -custom executable can only run itself (I think). This really gets back to the question of why one would compile to bytecode. One reason would be to make OCaml Java-like - distribute bytecode to people who have the OCaml VM (ocamlrun) installed. I’m under the impression that the more common reason is to speed development. Compiling to bytecode is noticeably faster than compiling to native code. If I’m not mistaken, at least part of the reason dune favors -custom is because it statically links C/C++ libraries. If you link bytecode that depends on such a library and you do not use -custom then you have to deal with linking shared libs, which is more error-prone. And there is also `-output-complete-exe`. But if you’re going to go to the trouble of that or -custom you might as well use a`ocamlopt` since either way you won’t be distributing a bytecode-only executable. ---
**Author:** ![dinosaure](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dinosaure/32/16_2.png) [@dinosaure](https://discuss.ocaml.org/u/dinosaure)\ **Post date:** [April 18, 2025, 1:45pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/7 "2025-04-18T13:45:52Z")
> [@ferdv](#): > > However, in practice, I haven’t found anything on distributing or installing just the interpreter and runtime, separately from the rest of the tooling in the OCaml repository. I also haven’t found any Opam package (so far) that would appear to only include the runtime and standard library for running OCaml programs. How are people distributing their programs, at least to the various POSIX-conforming platforms, other than targeting them directly with native code? Currently, if portability is your primary concern, I have developed an OCaml to [Cosmopolitan](https://github.com/jart/cosmopolitan)/[APE](https://justine.lol/ape.html) port that provides [a new OCaml toolchain](https://github.com/dinosaure/esperanto) capable of producing _actually portable_ executables. An example in the [README.md](https://github.com/dinosaure/esperanto?tab=readme-ov-file#getting-started) file shows how to use such this _toolchain_. The support is only for OCaml 4.14, but I have OCaml 5 on my to-do list. ---
**Author:** ![dra27](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/dra27/32/5294_2.png) [@dra27](https://discuss.ocaml.org/u/dra27)\ **Post date:** [April 18, 2025, 7:24pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/8 "2025-04-18T19:24:39Z")
> [@mobileink](#): > > ocamlrun can run any bytecode executable. A -custom executable can only run itself (I think). Actually, it can run other things, although I think that’s unintentional (and bad) and one of the many bits of spin-off work from Relocatable OCaml is stopping that from being the case. ---
**Author:** ![mobileink](https://sea2.discourse-cdn.com/flex020/user_avatar/discuss.ocaml.org/mobileink/32/3295_2.png) [@mobileink](https://discuss.ocaml.org/u/mobileink)\ **Post date:** [April 18, 2025, 7:57pm UTC](https://discuss.ocaml.org/t/standalone-ocaml-runtime-package-source-code/16480/9 "2025-04-18T19:57:02Z")
I don’t think this is complicated enough. Let’s add that you can do `-make-runtime` if you want to distribute a customized ocamlrun.