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WebAssembly proposals

Active proposals

Proposals follow this process document.

Phase 5 - The Feature is Standardized (WG)

These proposals have not yet been merged to the spec. Merged proposals are listed in Finished Proposals.

ProposalChampion
Tail callAndreas Rossberg
Extended Constant ExpressionsSam Clegg
Typed Function ReferencesAndreas Rossberg
Garbage collectionAndreas Rossberg
Multiple memoriesAndreas Rossberg
Relaxed SIMDMarat Dukhan & Zhi An Ng
Custom Annotation Syntax in the Text FormatAndreas Rossberg
Branch HintingYuri Iozzelli

Phase 4 - Standardize the Feature (WG)

ProposalChampion
ThreadsConrad Watt
Exception handlingHeejin Ahn & Ben Titzer
JS String BuiltinsRyan Hunt

Phase 3 - Implementation Phase (CG + WG)

ProposalChampion
Memory64Sam Clegg
Web Content Security PolicyFrancis McCabe
JS Promise IntegrationRoss Tate and Francis McCabe
Type Reflection for WebAssembly JavaScript APIIlya Rezvov
ESM IntegrationAsumu Takikawa, Ms2ger & Guy Bedford

Phase 2 - Proposed Spec Text Available (CG + WG)

ProposalChampion
Relaxed dead code validationConrad Watt and Ross Tate
Numeric Values in WAT Data SegmentsEzzat Chamudi
Instrument and Tracing TechnologyRichard Winterton
Extended Name SectionAshley Nelson
Custom Page SizesNick Fitzgerald
Stack SwitchingFrancis McCabe & Sam Lindley

Phase 1 - Feature Proposal (CG)

ProposalChampion
Type ImportsAndreas Rossberg
Component ModelLuke Wagner
WebAssembly C and C++ APIAndreas Rossberg
Flexible VectorsPetr Penzin & Tal Garfinkel
Call TagsRoss Tate
Constant TimeSunjay Cauligi, Garrett Gu, John Renner, Hovav Shacham, Deian Stefan, Conrad Watt
JS Customization for GC ObjectsAsumu Takikawa
Memory controlDeepti Gandluri & Ben Visness
Reference-Typed StringsAndy Wingo
ProfilesAndreas Rossberg
Rounding VariantsKloud Koder
Shared-Everything ThreadsAndrew Brown, Conrad Watt, and Thomas Lively
Frozen ValuesLéo Andrès and Pierre Chambart
Compilation HintsEmanuel Ziegler
Half PrecisionIlya Rezvov
Compact Import SectionRyan Hunt
128-Bit ArithmeticAlex Crichton and Jamey Sharp

Phase 0 - Pre-Proposal (CG)

ProposalChampion

Implementation status

Implementation status of most proposals in various wasm engines is available on https://webassembly.org/features/

Contributing new proposals

Please see Contributing to WebAssembly for the most up-to-date information on contributing proposals to standard.