WebAssembly/spec

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WebAssembly specification, reference interpreter, and test suite.

Stars: 3.5k
Forks: 539
Open beginner issues: 0
Indexed issues: 73
Avg merge: 2d 1h
Merged PRs (30d): 13

Dominant language: WebAssembly
License: No license data
Last GitHub push: Sep 11, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: No beginner labels indexed

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73 open issues indexed

[spectec] Wasm 1.0: `$instantiate` missing premises Open

Difficulty 3/5 1-2 days Newbie friendliness 68/100

WebAssembly/spec#2245 · Opened Sep 4, 2026
Incorrect implementations of unreachable `ref.as_non_null` validation Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

WebAssembly/spec#2235 · 9 comments · Opened Aug 28, 2026
[spectec] Missing and wrong side conditions in the middle-end Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#2196 · Opened Jun 23, 2026
Structured cloning of WebAssembly.Memory is not defined Open

Difficulty 4/5 3-5 days Newbie friendliness 48/100

WebAssembly/spec#2155 · 2 comments · Opened May 4, 2026
Double rounding fix is (still) wrong in Windows Open

Difficulty 4/5 3-5 days Newbie friendliness 45/100

WebAssembly/spec#2150 · 1 comment · Opened Apr 23, 2026
Simplify JS-API test syncing Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

WebAssembly/spec#2130 · 5 comments · Opened Mar 31, 2026
[js-api] Ambiguity in WebAssembly.instance() importObject requirement with JS builtins imports Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#2102 · 1 comment · 1 reaction · Opened Mar 9, 2026
Should importing or exporting a function count as declaring it for ref.func? Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

WebAssembly/spec#2072 · 17 comments · Opened Feb 4, 2026
Some links in the archived version of the W3C/bikeshed version of the Wasm spec are broken Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#2051 · 1 comment · Opened Jan 12, 2026
Minor errors in 3.0 binary format Open

Difficulty 2/5 1-3 hours Newbie friendliness 42/100

WebAssembly/spec#2041 · 1 comment · Opened Dec 8, 2025
[js-api] Is the exception propagation model used consistently? Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#2040 · Opened Dec 4, 2025
[spec] Missing hyperlink for `.refs` in `table.set` reduction rule prose Open

WebAssembly/spec#2039 · 1 assignee · Opened Dec 3, 2025
[js-api] Ambiguity in `WebAssembly.instantiate(bytes)` if `WebAssembly.Module` is a thenable Open

Difficulty 5/5 Over a week Newbie friendliness 42/100

WebAssembly/spec#2034 · 3 comments · Opened Nov 26, 2025
[js-api] Possible alignment of abstract closure conventions with ECMA-262 Open

Difficulty 4/5 3-5 days Newbie friendliness 38/100

WebAssembly/spec#2027 · 2 comments · Opened Nov 6, 2025
Inconsistencies across multiple pages of instruction lists Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#2020 · 3 comments · Opened Oct 25, 2025
Update bib references/citation for WASM 3.0 Open

Difficulty 1/5 Under an hour Newbie friendliness 58/100

WebAssembly/spec#2018 · 1 comment · 1 reaction · Opened Oct 22, 2025
gc-exotic-objects `[[PreventExtensions]]` should return `true`. Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#2008 · 10 comments · Opened Oct 9, 2025
[js-api] Unclear spec for `-0` in `ToWebAssemblyValue`? Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1984 · 9 comments · Opened Sep 23, 2025
[js-api] Are Wasm-gc abstract heap types included in the JS API of e.g. WebAssembly.Global? Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

WebAssembly/spec#1980 · 10 comments · Opened Sep 22, 2025
The reference interpreter became up to 20 times slower after a87fffc Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

WebAssembly/spec#1979 · 1 comment · Opened Sep 20, 2025
[js-api] Informal description about "the index of the host function" Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1959 · 4 comments · Opened Aug 18, 2025
[js-api] Exposing Wasm-specific internal structure Open

Difficulty 5/5 Over a week Newbie friendliness 28/100

WebAssembly/spec#1958 · 2 comments · Opened Aug 18, 2025
[js-api] Monitoring the execution of Wasm Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1957 · 6 comments · Opened Aug 18, 2025
New testsuite organization Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1950 · 17 comments · Opened Jul 23, 2025
Semi-implicit dropping of initialization should be explicited Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

WebAssembly/spec#1965 · 1 comment · Opened Jul 2, 2025
[spec] Disagreement between the tests and the spec on the import of tags Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#1931 · Opened Jun 19, 2025
Table in PDF runs off page Open

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

WebAssembly/spec#1923 · 4 comments · Opened Jun 17, 2025
wasm64: support memory larger than 16 GB Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1892 · 15 comments · 13 reactions · Opened Apr 17, 2025
[js-api] Ambiguous and inconsistent handling of implementation limits Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

WebAssembly/spec#1863 · 5 comments · Opened Jan 13, 2025
Clean up JS/HTML-wrapped core test export for WPT Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1860 · 1 comment · 1 reaction · Opened Dec 20, 2024
Inconsistencies with memory and table max limits in core spec, js-api spec and tests Open

Difficulty 4/5 3-5 days Newbie friendliness 28/100

WebAssembly/spec#1864 · 3 comments · 1 reaction · Opened Nov 13, 2024
Self-review of security and privacy questionnaire for 2.0 CR transition Open

privacy-tracker security-tracker

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1830 · Opened Oct 7, 2024
Bikeshed is stripping backslashes from some latex newline commands Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1823 · 5 comments · Opened Oct 4, 2024
Don't emit `module definition` or `module instance` unless present in input when generating `.bin.wast` Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#1811 · 2 comments · Opened Sep 23, 2024
Markup inside the PDF's validation section in the table of content Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#1810 · 5 comments · Opened Sep 23, 2024
UINT32_MAX as various index values Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1807 · 1 comment · Opened Sep 20, 2024
Check against i18n checklist for CR transition for wasm 2.0 Open

i18n-tracker

Difficulty 4/5 3-5 days Newbie friendliness 25/100

WebAssembly/spec#1806 · 2 comments · Opened Sep 18, 2024
Check against a11y checklist for CR transition Open

a11y-tracker

Difficulty 4/5 3-5 days Newbie friendliness 30/100

WebAssembly/spec#1805 · Opened Sep 18, 2024
Spec tests that conflict with mature proposals Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

WebAssembly/spec#1788 · 13 comments · 3 reactions · Opened Aug 21, 2024
Change direction in wording around stack unwinding Open

Difficulty 1/5 Under an hour Newbie friendliness 50/100

WebAssembly/spec#1781 · 2 comments · Opened Aug 15, 2024
Time to delete the old `master` branches? Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

WebAssembly/spec#1755 · 5 comments · 4 reactions · Opened Jun 17, 2024
[JS API] 'run a host function' and 'create a host function' don't consistently handle completion records Open

Difficulty 4/5 3-5 days Newbie friendliness 42/100

WebAssembly/spec#1743 · 1 comment · Opened Apr 9, 2024
Missing ability to access built older versions of the WebAssembly specification in archivable form Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1736 · 2 comments · Opened Mar 1, 2024
SIMD test optimization? Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

WebAssembly/spec#1724 · 3 comments · Opened Feb 8, 2024
Improve SIMD test diversity Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#1703 · 1 comment · Opened Nov 5, 2023
[JS Generator] Add scope for each wasm instance Open

Difficulty 3/5 1-2 days Newbie friendliness 38/100

WebAssembly/spec#1698 · 1 comment · Opened Oct 27, 2023
stack size mismatch error messages are unclear Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

WebAssembly/spec#1675 · Opened Aug 2, 2023
[Spec] Please do not use MathML for non-mathematical items Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1672 · 6 comments · 3 reactions · Opened Jul 19, 2023
Clarification regarding value parameter for WebAssembly.Global etc. Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

WebAssembly/spec#1660 · 3 comments · Opened Jun 2, 2023
assert_invalid and assert_malformed produce inconsistent JS tests Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

WebAssembly/spec#1647 · 6 comments · Opened May 4, 2023

WebAssembly/spec

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