--- title: Kotlin Toolchain 0.12: Multiplatform Library Publishing,... description: Kotlin Toolchain 0.12.0 adds preview support for publishing multiplatform libraries (not just JVM), a preview of building Wasm web applications, and Compose... canonical: https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Kotlin Toolchain 0.12: Multiplatform Library Publishing, Wasm Apps, and More | daily.dev og:description: Kotlin Toolchain 0.12.0 adds preview support for publishing multiplatform libraries (not just JVM), a preview of building Wasm web applications, and Compose... og:url: https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl og:image: https://api.daily.dev/og/posts/6rrJLWcJL.png og:image:alt: Kotlin Toolchain 0.12: Multiplatform Library Publishing, Wasm Apps, and More og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Kotlin Toolchain 0.12: Multiplatform Library Publishing, Wasm Apps, and More **[JetBrains](https://daily.dev/sources/jetbrains)** · 7 min read · 5 upvotes · 0 comments ## Summary Kotlin Toolchain 0.12.0 adds preview support for publishing multiplatform libraries (not just JVM), a preview of building Wasm web applications, and Compose Hot Reload usable from the command line, including a new MCP server letting AI agents interact with hot-reloading apps. It also tightens Maven Central publication compliance, improves terminal UI diagnostics and test status, adds IDE improvements for Compose preview, Android tooling, and iOS run configurations, introduces a new '//' prefixed local dependency path format, raises the minimum supported JDK to 17 and minimum Kotlin compiler to 2.2.20, and bumps default versions for Kotlin, JDK, JUnit, KSP, Ktor, Spring Boot, DataFrame, and kotlinx.rpc. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### Does Kotlin Toolchain 0.12 support publishing multiplatform libraries, not just JVM libraries? Yes, starting with Kotlin Toolchain 0.12.0, multiplatform library publishing is supported using the same configuration as JVM-only publishing introduced in 0.11. It publishes the common API, one artifact per platform, sources, and module publication metadata, including commonized and per-platform cinterop bindings, making the result consumable from Gradle projects like any other multiplatform library. _Teams weighing Kotlin Multiplatform for shared libraries can track toolchain updates like this on daily.dev._ ### What is the minimum JDK version required by Kotlin Toolchain 0.12? JDK 17 or higher is required to compile code with Kotlin Toolchain 0.12, with a clear diagnostic now shown if an older JDK is used. Developers can still target lower JREs at runtime using settings.jvm.release. The minimum supported Kotlin compiler version was also raised, from 2.1.10 to 2.2.20, aligning with the Kotlin standard library's security support policy. _Developers planning a Kotlin toolchain upgrade can check version requirements like these on daily.dev before migrating._ ### Why did Kotlin Toolchain reduce the number of checksum files published to Maven Central? Kotlin Toolchain 0.12 reduces published files to comply with new Maven Central publishing quotas that Sonatype will soon enforce. The .asc.sha1 signature checksum is no longer published, and only .md5 and .sha1 checksums are published by default; .sha256 and .sha512 can still be enabled via the settings.publishing.checksums configuration option. _Library maintainers adjusting to new Maven Central quotas can follow ecosystem changes like this on daily.dev._ ## Similar posts on daily.dev - [Kotlin Toolchain 0.11: The Next Step for Amper](https://daily.dev/posts/kotlin-toolchain-0-11-the-next-step-for-amper-ndtqq6px9) · JetBrains · 3 upvotes · 0 comments - [Kotlin Weekly \#526](https://daily.dev/posts/kotlin-weekly-526-catkarbd9) · Kotlin Weekly · 2 upvotes · 0 comments - [JetBrains Amper build tool adds Compose Hot Reload](https://daily.dev/posts/jetbrains-amper-build-tool-adds-compose-hot-reload-7zhbfvjxt) · InfoWorld · 0 upvotes · 0 comments - [Kotlin 2.4.0 Released](https://daily.dev/posts/kotlin-2-4-0-released-mwoy7ksjv) · JetBrains · 9 upvotes · 0 comments --- Tags: [#kotlin](https://daily.dev/tags/kotlin), [#webassembly](https://daily.dev/tags/webassembly), [#gradle](https://daily.dev/tags/gradle), [#compose-multiplatform](https://daily.dev/tags/compose-multiplatform) [View this post on daily.dev](https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Kotlin Toolchain 0.12: Multiplatform Library Publishing, Wasm Apps, and More","url":"https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl"},"datePublished":"2026-09-03T11:41:18.363Z","dateModified":"2026-09-14T09:23:24.624Z","description":"Kotlin Toolchain 0.12.0 adds preview support for publishing multiplatform libraries (not just JVM), a preview of building Wasm web applications, and Compose...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3bc9fa1a706ef56535f54aa9e1e140cb?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/3bc9fa1a706ef56535f54aa9e1e140cb?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"JetBrains","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"JetBrains","logo":"https://media.daily.dev/image/upload/t_logo,f_auto/v1/logos/53ecf0c676f34b3896ee109609d91efa","url":"https://daily.dev/sources/jetbrains"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":5},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"kotlin,webassembly,gradle,compose-multiplatform","timeRequired":"PT7M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"JetBrains","item":"https://daily.dev/sources/jetbrains"},{"@type":"ListItem","position":3,"name":"Kotlin Toolchain 0.12: Multiplatform Library Publishing, Wasm Apps, and More"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/kotlin-toolchain-0-12-multiplatform-library-publishing-wasm-apps-and-more-6rrjlwcjl#faq","mainEntity":[{"@type":"Question","name":"Does Kotlin Toolchain 0.12 support publishing multiplatform libraries, not just JVM libraries?","acceptedAnswer":{"@type":"Answer","text":"Yes, starting with Kotlin Toolchain 0.12.0, multiplatform library publishing is supported using the same configuration as JVM-only publishing introduced in 0.11. 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