Roadmap

In November 2017, WebAssembly CG members representing four browsers, Chrome, Edge, Firefox, and WebKit, reached consensus that the design of the initial (MVP) WebAssembly API and binary format is complete to the extent that no further design work is possible without implementation experience and significant usage.

After the initial release, WebAssembly has been gaining new features through the standardization process. For the complete list of current proposals and their respective stages, check out the WebAssembly/proposals repo.

The table below aims to track implemented features in popular engines:

	Chrome	Firefox	Safari	Wasmtime	Wasmer	Node.js	Deno	wasm2c
Standardized features
JS BigInt to Wasm i64 integration	85	78	14.1^[d]	N/A	N/A	15.0	1.1.2	N/A
Bulk memory operations	75	79	15	0.20	1.0	12.5	0.4	1.0.30
Extended constant expressions	114	^[c]				^[g]	^[l]
Multi-value	85	78		0.17	1.0	15.0	1.3.2	1.0.24
Mutable globals	74	61			0.7	12.0	0.1	1.0.1
Reference types	96	79	15	0.20	2.0	17.2	1.16	1.0.31
Non-trapping float-to-int conversions	75	64	15			12.5	0.4	1.0.24
Sign-extension operations	74	62	14.1^[d]			12.0	0.1	1.0.24
Fixed-width SIMD	91	89	16.4	0.33	2.0	16.4	1.9
Tail calls	112					^[j]	^[o]
In-progress proposals
Exception handling	95	100	15.2			17.0	1.16	^[q]
Garbage collection	^[a]
Memory64	^[b]	^[c]		^[e]		^[h]	^[m]	^[r]
Multiple memories				^[f]				^[s]
Relaxed SIMD	^[b]	^[c]				^[i]	^[n]
Threads and atomics	74	79	14.1^[d]	N/A	N/A	16.4	1.9
Type reflection	^[b]	^[c]			2.0	^[k]	^[p]

Requires flag chrome://flags/#enable-webassembly-garbage-collection
Requires flag chrome://flags/#enable-experimental-webassembly-features
Enabled in Nightly, unavailable in Beta/Release
Supported in desktop Safari since 14.1 and iOS Safari since 14.5
Requires flag --wasm-features=memory64
Requires flag --wasm-features=multi-memory
Requires flag --experimental-wasm-extended-const
Requires flag --experimental-wasm-memory64
Requires flag --experimental-wasm-relaxed-simd
Requires flag --experimental-wasm-return-call
Requires flag --experimental-wasm-type-reflection
Requires flag --v8-flags=--experimental-wasm-extended-const
Requires flag --v8-flags=--experimental-wasm-memory64
Requires flag --v8-flags=--experimental-wasm-relaxed-simd
Requires flag --v8-flags=--experimental-wasm-return-call
Requires corresponding v8 flag (--v8-flags="...")
Requires flag --enable-exceptions
Requires flag --enable-memory64
Requires flag --enable-multi-memory

To detect supported features at runtime from JavaScript, check out the wasm-feature-detect library, which powers the “Your browser” column above.