Ocsigen: summary of recent releases

We do not announce very often our releases on this forum. Here is a roundup of recent releases to make amends.

Many releases of Js_of_ocaml last year, with important features like the support of OCaml 5 effects, global dead-code elimination, support for modern JavaScript and a huge list of improvements and fixes.
There is now also a new backend for js_of_ocaml, Wasm_of_ocaml written by @vouillon, to compile to WebAssembly. It can be used as a replacement for js_of_ocaml with very few changes.

Eliom, the OCaml Web framework, has now reached version 10.2. Amongst the most recent changes:

  • The Dune-based build system is now the default one for client-server apps
  • compatibility with OCaml 5
  • Reactive programming: Update to recent versions of js_of_ocaml, which support weak pointers
  • Documentation improvements

An experimental version is also available to build WASM applications with wasm_of_ocaml

Ocsigen-Start version 6.1

  • removes a dependency on Ocamlnet to make it compatible with OCaml 5. No default email function is now provided. Warning: this might be a regression if you use the default email-sending function.
  • updates the dune-based build system

Tyxml 4.6 was released with fixes on some tags and options.

Lwt reached version 5.7

Several maintenance releases of Ocsigen-Toolkit

The Ocsigen team wishes you a happy new year!


The dev experience improved dramatically via the move towards dune builds! Very nice :clap:

Not having type info bubble up via the lsp felt a bit of a hindrance so I’m glad this looks like a solved problem, even on Eliom files!

Looking forward to play more with this tech

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Indeed, it would be great to have better editor support.
It is currently possible to get the info bubble with the right configuration, but you must choose whether it is for the client or server side API.

Be Sport has a repository with the configuration files used by some developers that could be a starting point for improving the editors’ configuration: GitHub - besport/dotfiles

Thanks for the update, @Vincent_Balat.

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Ocsigen Start 6.2.0 was released a few days ago.
It simplifies the code of the demo application by removing first-class modules and making the code more standard.


Eliom 10.3.1 released:


Thank you very much for your work on Ocsigen. I’m just starting out with it, but I’m already very impressed. What a unique project.

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Eliom 10.4:

  • Basic client-server distillery template: sqlite is now the default backend
  • Basic template now has license unlicense
  • Basic template fixes
  • Compatibility with Tyxml >= 4.6.0 (by Vincent Laporte)
  • Compatibility with OCaml 5.2 (Eliom 10.4.1)

Ocsigen Start 6.3

  • Adding license Unlicense to the template
  • Dependecy to Tyxml >= 4.6