# Swift 6.4 Released

DevFeed: [Swift 6.4 Released](<https://devfeed.tech/articles/swift-6-4-released-26971.md>)

Original publisher: [Read original article](<https://swift.org/blog/swift-6.4-released/>)

Author: Holly Borla

Published: 2026-09-15T07:30:00Z

Content type: release

Language: en

Sources: [Swift.org](<https://devfeed.tech/sources/swift-org.md>)

Topics: [Swift](<https://devfeed.tech/topics/swift.md>), [cross-platform](<https://devfeed.tech/topics/cross-platform.md>), [Programming](<https://devfeed.tech/topics/programming.md>), [Memory Safety](<https://devfeed.tech/topics/memory-safety.md>), [WebAssembly](<https://devfeed.tech/topics/web-assembly.md>), [browser](<https://devfeed.tech/topics/browser.md>), [Microcontroller](<https://devfeed.tech/topics/microcontroller.md>)

Tags: [cross-platform](<https://devfeed.tech/tags/cross-platform.md>), [errors](<https://devfeed.tech/tags/errors.md>), [libraries](<https://devfeed.tech/tags/libraries.md>), [linux](<https://devfeed.tech/tags/linux.md>), [macos](<https://devfeed.tech/tags/macos.md>), [memory-safety](<https://devfeed.tech/tags/memory-safety.md>), [programming](<https://devfeed.tech/tags/programming.md>), [swift](<https://devfeed.tech/tags/swift.md>), [webassembly](<https://devfeed.tech/tags/webassembly.md>)

## AI overview

Swift 6.4 is now available with Swift Build as the default in Swift Package Manager, a stable cross-platform Subprocess API, expanded C++20 and Java interoperability, faster WebAssembly support, broader embedded Swift capabilities, and performance improvements that maintain memory safety.

## Source excerpt

Swift 6.4 is now available. Swift aims to be a great choice across the stack, from apps and servers to systems code, embedded devices, and the browser. This release deepens that support, and makes everyday code easier to write. Highlights include: Swift Build is now the default in Swift Package Manager, so your projects build the same way on Linux, macOS, and Windows. Subprocess reaches 1.0, a stable, cross-platform way to run and interact with other programs from Swift, from command-line tools to streaming processes. Interoperability reaches further, with Swift's Span now bridging directly with C++20's std::span, and Swift/Java interop extending its async and callback support. Swift runs faster in the browser, with WebAssembly bridging through JavaScriptKit up to 40 times faster, and the Wasm SDK available directly from Swift.org. Embedded Swift grows more capable, with support for existential types and richer error handling for microcontroller-class targets. Performance improves while maintaining memory safety, with new array types that hold non-copyable elements without copy-on-write overhead, and the new Iterable protocol for iterating without copies. There's so much more. Read on for a detailed guide to the new changes, or see the Swift Evolution dashboard for the full list of proposals in Swift 6.4. Simpler and clearer code Swift 6.4 streamlines your day-to-day programming to make your code simpler and clearer. More natural optional some and any types. When writing an optional some or any type, you no longer have to wrap the type in parentheses. Instead of (some Rocket)?, you can simply write some Rocket? (SE-0521). Source-level control over compiler warnings. When you need to control the behavior of warnings in your project, such as suppressing warnings or promoting them to errors, you can now define the warning behavior directly in your code using the new @diagnose attribute (SE-0522). Clarify which API to use when multiple libraries conflict. When multiple