winget install --id BytecodeAlliance.Wasmtime.PortableAbout Wasmtime
Wasmtime is a Bytecode Alliance project that is a standalone wasm-only optimizing runtime for WebAssembly and WASI. It runs WebAssembly code outside of the Web, and can be used both as a command-line utility or as a library embedded in a larger application.
What's new in 47.0.3
47.0.0 Released 2026-07-20. Added • Wasmtime now has the WebAssembly GC proposal enabled by default. #13594 • Wasmtime now has the WebAssembly exception-handling proposal enabled by default. #13603 • Cranelift now supports the compact unwind format on Mach-O platforms. #13586 • Wasmtime now supports bounds-checked unsafe intrinsics which take spectre mitigations into account. #13597 • The wasmtime::Engine type now supports reflection to determine the value of most Config options that were selected during creation. #13671 • Support for fibers on unsupported architectures is now supported through an opt-in compile time Cargo feature defining a C API embedders can implement. #13620 • Embedders can now create an ArrayRef with a memcpy-style constructor. #13716 • A new Accessor::poll_ready_for_concurrent_call API can be used to detect when backpressure indicates that a function is ready to be invoked. #13683 Changed • Support for wasi-threads and Wasmtime's wasi-common crate have been removed. For more information see the associated RFC in Wasmtime. #13558 • The call_indirect instruction of final super types has been optimized when the GC proposal is enabled. #13572 • Cranelift's *_imm builder helpers have been deprecated in favor of *_imm_{s,u} helpers. #13583 • The wasmtime CLI's syntax supported for --invoke with components now supports fully qualified WIT interface names. #13564 • Cranelift's stack_{load,store} instructions have been removed. #13580 • Cranelift's {band,bor,bxor}_not instructions have been removed. #13590 • Cranelift's global_value instruction has been remove...
Version history
| Version | Updated | Notes |
|---|---|---|
| 47.0.3 | Unknown | 47.0.0 Released 2026-07-20. Added • Wasmtime now has the WebAssembly GC proposal enabled by default. #13594 • Wasmtime now has the WebAssembly exception-handling proposal enabled by default. #13603 • Cranelift now suppor... |
| 47.0.0 | Unknown | 47.0.0 Released 2026-07-20. Added - Wasmtime now has the WebAssembly GC proposal enabled by default. #13594 - Wasmtime now has the WebAssembly exception-handling proposal enabled by default. #13603 - Cranelift now suppor... |
| 46.0.1 | Unknown | 46.0.1 Released 2026-06-24. Fixed - WASI hard links and renames check wasmtime-wasi's FilePerms for destination GHSA-4ch3-9j33-3pmj - Explicit hint for generic call in wasmtime wit-bindgen. #13719 |
| 46.0.0 | Unknown | 46.0.0 Released 2026-06-22. Added - Added opt-in support for the WebAssembly branch-hinting proposal: the metadata.code.branch_hint custom section is parsed and used to mark cold blocks during Cranelift compilation, behi... |
| 45.0.2 | Unknown | 45.0.2 Released 2026-06-15. Fixed - Leak in WASIp1 fd_renumber implementation. GHSA-3p27-qvp9-27qf |
| 45.0.1 | Unknown | 45.0.1 Released 2026-06-05. Fixed - Fixed regression with WASIp2 zero-delay clocks/timers: allow repeat calls to .ready() to make progress. #13511 |
| 45.0.0 | Unknown | 45.0.0 Released 2026-05-21. Added - Winch now respects the enable_nan_canonicalization setting. #12939 - Initial support for invoking component functions asynchronously has been added to the C API. #12973 - Cranelift's s... |
| 44.0.1 | Unknown | 44.0.1 Released 2026-04-30. Fixed - Panic when allocating a table exceeding the size of the host's address space. GHSA-p8xm-42r7-89xg |
| 44.0.0 | Unknown | 44.0.0 Released 2026-04-20. Added - The wasmtime CLI now supports a -g flag which runs a built-in wasm program to host a gdbstub-compatible server (can be connected to with LLDB) to debug guest programs. #12756 #12771 #1... |
| 43.0.1 | Unknown | 43.0.1 Released 2026-04-09. Fixed - Miscompiled guest heap access enables sandbox escape on aarch64 Cranelift. GHSA-jhxm-h53p-jm7w - Wasmtime with Winch compiler backend may allow a sandbox-escaping memory access. GHSA-x... |
| 43.0.0 | Unknown | 43.0.0 Released 2026-03-20. Added - Wasmtime now supports the WASIp3 snapshot 0.3.0-rc-2026-03-15. #12557 - The number of frames captured in backtrace collection can now be configured. #12542 - Wasmtime now supports fine... |
| 42.0.1 | Unknown | 42.0.1 Released 2026-02-25. Fixed - Fix some minor bindgen! issues with anyhow: true #12658 |
| 42.0.0 | Unknown | 42.0.0 Released 2026-02-20. Added - Cranelift now supports bitwise operations on floats on aarch64. #12326 - Cranelift now supports NaN canonicalization of f16 and f128. #12337 - Wasmtime has gained minimal support to im... |
| 41.0.3 | Unknown | 41.0.3 Released 2026-02-04. Fixed - Fix an incorrect mid-end optimization rule that could cause a compiler panic due to mismatched types. #12504 |
| 41.0.2 | Unknown | 41.0.2 Released 2026-02-03. Fixed - Reduce the dependencies of the wasmtime-internal-jit-icache-coherence crate. #12446 |
| 41.0.1 | Unknown | 41.0.1 Released 2026-01-26. Fixed - Fixed a bug in lowering of f64.copysign on x86-64 whereby when combined with an f64.load, the resulting machine code could read 16 bytes rather than 8 bytes. This could result in a seg... |
| 41.0.0 | Unknown | 41.0.0 Released 2026-01-20. Added - Support for {Future,Stream}Any in the component model has improved. #12142 - Wasmtime has initial support for breakpoints and single-stepping with the debug feature for guest programs.... |
| 40.0.2 | Unknown | 40.0.2 Released 2026-01-14. Fixed - A possible stack overflow in the x64 backend with cmp emission has been fixed. #12333 - Some ISLE optimization rules which created erroneous IR for vector inputs have been fixed. #1217... |
| 40.0.1 | Unknown | 40.0.1 Released 2026-01-07. Changed - This release is a test of Wasmtime's CI-based crate publishing infrastructure. Wasmtime is switching to crates.io-based trusted publishing for this release and is testing that everyt... |
| 40.0.0 | Unknown | 40.0.0 Released 2025-12-20. Added - WASIp3 support for wasi:http now implements Response::from_http to convert from standard Rust types to WASI types. #12063 - Cranelift now supports a "patchable" ABI which has a maximum... |