Deprecation status

[radon-at-beeper]

It's a little perplexing that fwcd/kotlin-language-server is marked deprecated, because the suggested replacement Kotlin/kotlin-lsp:

• is not open source,
• does not have a stable release,
• does not accept contributions,
• goes months between versions that can be run,
• is marked as "experimental, pre-alpha, exploratory",
• and seemingly is never planned for open source (unless I misunderstand what the plan to have an "explicit dependency on IntelliJ" means).

Maybe there is a reason for fwcd/kotlin-language-server or a successor to continue to exist?

[DonnieWest]

https://github.com/Kotlin/kotlin-lsp/blob/main/LICENSE.txt

Seems pretty clear that it's APACHE licensed, so on the OSS front it seems like a valid alternative

but I think the real answer is fwcd is just busy and no one else really took over the project. So an alternative popped up and the burden of supporting this was simply passed over. It makes way more sense to just allow the actual kotlin project to support their own lsp

Nothing stopping you from forking this and maintaining it though 😉

[radon-at-beeper]

The component in the Github repo is open-source, but it doesn't function without additional extra proprietary components. This is mentioned in the README as well as in Github issues.

[DonnieWest]

That's what I get for drive-by responding rather than checking in depth 🤦 . The point still stands though

[walker84837]

Since there seems to be interest in keeping this project usable, I've started maintaining a fork that continues development.

I'm working on merging several outstanding PRs, applying stability fixes, modernizing the toolchain (requires at least Java 21), and addressing a few long-standing issues that affected my own usage. The goal is to keep the server functional and incrementally improve it rather than let it stagnate.

If anyone is interested in contributing or testing, the fork is here: https://codeberg.org/winlogon/ktlsp

Happy to collaborate with anyone who would like to help continue maintaining it.

[walker84837]

Just a small update for anyone following this thread: I've just published ktlsp 1.4.0-RC1.

This release includes (non-exhaustively):

• numerous bug fixes
• performance improvements (reduced RAM usage, virtual threads, and other optimizations)
• updated Kotlin compatibility (from 2.1.0 to 2.2.21), allowing support for Kotlin 2.3.x projects
• additional LSP features, including Go to Type Definition, Go to Declaration, Call Hierarchy, and completions for synthesized Kotlin accessors (and more)
• Java 21 as the minimum supported version. Compiles on Java 21 and runs on Java 25.
• hover now displays Javadoc from JDK sources
• Gradle Tooling API as the primary classpath resolution mechanism
• continued maintenance, documentation, and quality-of-life improvements

The project is still under active development, so I'd really appreciate feedback and bug reports from anyone interested in trying it.

The goal is to provide a maintained Kotlin language server while longer-term work (i.e., the eventual migration to Kotlin's K2/FIR frontend) is planned.