The End of Kotlin Notebook: What It Means for Developers and
Key takeaways
- JetBrains is discontinuing Kotlin Notebook to focus on core IDE and language improvements.
- Existing notebooks will remain readable but will not receive updates; exporting them is recommended.
- The Kotlin Jupyter kernel is the most direct replacement for interactive notebook workflows.
- IntelliJ IDEA scratch files, REPL, and online playgrounds provide lightweight alternatives for experimentation.
- The sunset creates an opportunity to strengthen Kotlin’s core tooling, foster community solutions, and adopt more robust documentation practices.
JetBrains recently announced that Kotlin Notebook will be sunsetted, marking the end of an ambitious experiment to bring an interactive, notebook‑style workflow directly into the IntelliJ ecosystem. While the news may feel like a setback for developers who embraced the notebook paradigm for data‑science, teaching, or rapid prototyping, the decision also opens a conversation about where Kotlin is headed and how the community can adapt.
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Why Kotlin Notebook Was Born
Kotlin Notebook was introduced as a response to the growing popularity of Jupyter notebooks in the Python world. Data scientists, educators, and hobbyists love the ability to mix executable code, rich visualizations, and narrative text in a single document. JetBrains aimed to give Kotlin the same expressive power, leveraging its strong type system, coroutine support, and seamless interoperability with Java libraries.
Key motivations included:
- Lowering the barrier for Kotlin developers to experiment with data‑science libraries (e.g., Kotlin‑DL, Kotlin‑Plot). - Providing a unified experience for teams that already use IntelliJ IDEA for production code. - Showcasing Kotlin’s versatility beyond Android and backend development.
The Decision to Sunset
In a concise blog post, JetBrains explained that the notebook experience would be discontinued in favor of focusing resources on core IDE features and the broader Kotlin ecosystem. Several factors contributed to this shift:
1. Limited Adoption – Despite a passionate niche, overall usage numbers lagged behind expectations, making it difficult to justify continued investment. 2. Maintenance Overhead – Keeping the notebook engine compatible with rapid releases of Kotlin, IntelliJ, and third‑party libraries required substantial engineering effort. 3. Strategic Focus – JetBrains wants to prioritize features that benefit the majority of Kotlin users, such as improved debugging, refactoring, and multiplatform support.
The announcement also emphasized that existing notebooks will remain readable, but no further updates or bug fixes will be released.
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Immediate Impact on Developers
1. Existing Projects
If you have active Kotlin Notebook files (*.knot), they will continue to open in IntelliJ IDEA. However, you should export any critical notebooks to static formats (Markdown, HTML, or PDF) to preserve the content. The lack of future updates means that compatibility with newer Kotlin versions may degrade over time.
2. Learning and Teaching
Educators who built curricula around Kotlin Notebook will need to pivot. Options include:
- Converting notebooks to standard Kotlin scripts (.kts) and pairing them with explanatory Markdown files.
- Adopting Jupyter with the Kotlin kernel – an officially supported kernel that runs Kotlin code inside classic Jupyter notebooks.
- Using online platforms like GitHub Codespaces or Replit that support Kotlin REPLs.
3. Data‑Science Workflows
Data‑science practitioners lose a tightly integrated environment, but the Kotlin community has been nurturing alternatives:
- Kotlin‑DL and Kotlin‑Plot continue to evolve, and they can be used in regular Kotlin projects with a REPL or script. - Ktor for building lightweight APIs that serve model predictions. - Kotlin Multiplatform to share data‑processing logic across JVM, JS, and native targets.
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Viable Alternatives
Jupyter Notebook with Kotlin Kernel
The most direct replacement is the Kotlin Jupyter kernel, maintained by JetBrains and the community. It offers:
- Full notebook UI with rich media output. - Compatibility with existing Jupyter extensions (e.g., widgets, nbconvert). - Ability to run on remote servers, enabling collaborative work.
IntelliJ IDEA’s Scratch Files and REPL
IntelliJ’s scratch files provide a lightweight way to experiment with Kotlin snippets without creating a full project. Combined with the built‑in REPL, developers can quickly test ideas, albeit without the rich markdown‑code interleaving of a notebook.
Online Kotlin Playgrounds
Web‑based playgrounds such as Kotlin Playground (play.kotlinlang.org) now support multi‑cell execution and can embed code snippets in documentation, offering a low‑friction way to share runnable examples.
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Turning the Sunset into an Opportunity
The discontinuation of Kotlin Notebook should not be viewed solely as a loss. It can serve as a catalyst for several positive developments:
1. Strengthening Core Tooling – By reallocating resources, JetBrains can accelerate improvements in debugging, profiling, and refactoring for Kotlin, benefiting all developers. 2. Fostering Community‑Driven Solutions – Open‑source contributors can step in to create plugins or extensions that fill the notebook gap, ensuring the ecosystem remains vibrant. 3. Encouraging Multiplatform Adoption – Teams may explore Kotlin Multiplatform projects that combine backend processing, web UI (via Kotlin/JS), and native execution, moving beyond the notebook paradigm. 4. Improving Documentation Practices – With notebooks no longer the default, developers might adopt more robust documentation pipelines (e.g., Dokka, MkDocs, GitBook) that integrate code snippets, tests, and generated API docs.
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What to Do Next
If you’re a Kotlin developer impacted by this change, consider the following roadmap:
- Audit your existing notebooks and decide which ones need to be preserved. - Export valuable notebooks to Markdown or HTML for archival. - Migrate active notebooks to the Kotlin Jupyter kernel or to regular Kotlin scripts. - Explore IntelliJ scratch files and the REPL for quick experimentation. - Stay informed about upcoming JetBrains releases—features like Live Preview and Enhanced Multiplatform Support may offset the loss of notebook functionality.
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Looking Ahead
Kotlin’s momentum shows no sign of slowing. The language continues to expand into data‑science, web development, and native domains. While Kotlin Notebook’s sunset is a reminder that not every experimental feature will survive, it also underscores JetBrains’ commitment to focusing on the tools that deliver the greatest impact.
By embracing the alternatives and leveraging the strengths of the broader Kotlin ecosystem, developers can continue to innovate, prototype, and share knowledge—just perhaps in a slightly different format.
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Bottom line: The end of Kotlin Notebook is a strategic pivot, not a death knell. With thoughtful migration and an eye toward emerging tools, Kotlin developers can maintain productivity and keep pushing the language forward.