WebAssembly/binaryen

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Optimizer and compiler/toolchain library for WebAssembly

Stars: 8.6k
Forks: 885
Open beginner issues: 0
Indexed issues: 332
Avg merge: 1d 19h
Merged PRs (30d): 69

Dominant language: WebAssembly
License: Apache-2.0
Last GitHub push: Sep 19, 2026
Latest indexed: Sep 20, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted

Beginner friendly Everything

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332 open issues indexed

Missed optimization: failure to remove unnecessary locals usage with multi-value Open

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

WebAssembly/binaryen#8009 · Opened Oct 30, 2025
Branch hints fuzz bug Open

WebAssembly/binaryen#7920 · 3 comments · 1 assignee · Opened Sep 25, 2025
[wasm-opt] Global variables are not shared between threads, so using wasm-opt `--multi-memory-lowering` will cause memory corruption. Open

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

WebAssembly/binaryen#7916 · 1 comment · Opened Sep 23, 2025
Segfault with >120 versions on Linux Open

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

WebAssembly/binaryen#7911 · 8 comments · Opened Sep 22, 2025
Error when installing Open

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

WebAssembly/binaryen#7909 · 3 comments · Opened Sep 19, 2025
The wasm-reduce tool encountered an abnormal timeout under the condition of "--command=./wasmer run test.wasm" Open

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

WebAssembly/binaryen#7864 · 5 comments · Opened Aug 27, 2025
`--print-function-map` performs strange escaping on symbol name Open

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

WebAssembly/binaryen#7861 · 4 comments · Opened Aug 26, 2025
Dart deferred loading meta issue Open

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

WebAssembly/binaryen#7726 · 5 comments · Opened Jul 15, 2025
wasm-opt for WASIp2 Open

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

WebAssembly/binaryen#7712 · 10 comments · 1 reaction · Opened Jul 11, 2025
Name section: Support label names (id 3) Open

Difficulty 4/5 3-5 days Newbie friendliness 32/100

WebAssembly/binaryen#7707 · 5 comments · Opened Jul 10, 2025
wasm-opt is 35x slower on windows compared to linux Open

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

WebAssembly/binaryen#7705 · 5 comments · Opened Jul 9, 2025
Fails to compile with g++ 15 Open

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

WebAssembly/binaryen#7683 · 1 comment · Opened Jun 26, 2025
SimplifyLocals causes ineffective code Open

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

WebAssembly/binaryen#7672 · Opened Jun 21, 2025
RemoveUnusedBrs causes ineffective code Open

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

WebAssembly/binaryen#7661 · 1 comment · Opened Jun 17, 2025
[wasm-opt] `--minify-imports-and-exports-and-modules` does not report module renames. Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

WebAssembly/binaryen#7657 · 3 comments · Opened Jun 14, 2025
RemoveUnusedBrs fails to optimize control flow based dead code Open

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

WebAssembly/binaryen#7652 · 2 comments · Opened Jun 12, 2025
Tail-Call optimization Open

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

WebAssembly/binaryen#7647 · 1 comment · Opened Jun 10, 2025
wasm2js: function table undefined after calling async function Open

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

WebAssembly/binaryen#7645 · Opened Jun 7, 2025
Massive memory growth for -O3, -O4, -Os and -Oz, in ssa-nomerge Open

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

WebAssembly/binaryen#7644 · 7 comments · Opened Jun 7, 2025
Non-UTF string builtins constants? Open

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

WebAssembly/binaryen#7626 · 9 comments · Opened May 27, 2025
Create lowering pass for llvm usage of extended-const Open

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

WebAssembly/binaryen#7583 · Opened May 12, 2025
PossibleContents is not a lattice Open

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

WebAssembly/binaryen#7581 · 3 comments · Opened May 9, 2025
Pure calls / future of call.without.effects Open

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

WebAssembly/binaryen#7574 · 44 comments · Opened May 7, 2025
wasm-opt crashes with segmentation fault on big project Open

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

WebAssembly/binaryen#7570 · 8 comments · Opened May 5, 2025
Way of using binaryen without optimization passes Open

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

WebAssembly/binaryen#7566 · 4 comments · Opened May 2, 2025
Cannot optimize complex ge_u 0 out Open

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

WebAssembly/binaryen#7556 · Opened Apr 26, 2025
wasm-opt version on crates.io Open

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

WebAssembly/binaryen#7552 · 3 comments · 1 reaction · Opened Apr 25, 2025
`binaryen.js` seems to not longer be maintained Open

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

WebAssembly/binaryen#7526 · 9 comments · Opened Apr 18, 2025
Generate webassemby binary with DWARF information Open

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

WebAssembly/binaryen#7503 · 4 comments · Opened Apr 15, 2025
[Emitting Zero] [Local Tracking] General rule might not handle unary ne emitting zero bits well Open

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

WebAssembly/binaryen#7493 · 3 comments · Opened Apr 14, 2025
local-cse in O3 introduces side-effecting across structurally isolated sub-trees thus prevent const prop & DCE Open

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

WebAssembly/binaryen#7470 · 2 comments · Opened Apr 9, 2025
O2 regression in optimize-instructions due to coalesceLocals Open

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

WebAssembly/binaryen#7458 · 2 comments · Opened Apr 7, 2025
Provide some way for C & JS to visit and transform module code Open

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

WebAssembly/binaryen#7457 · 3 comments · Opened Apr 6, 2025
Cache locality and speed Open

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

WebAssembly/binaryen#7453 · 1 comment · 1 reaction · Opened Apr 4, 2025
local-cse introduces side effects via local.tee, blocking DCE in O3 Open

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

WebAssembly/binaryen#7440 · 4 comments · Opened Apr 3, 2025
wrong documentation when using `scripts/fuzz_opt.py --help` Open

Difficulty 1/5 Under an hour Newbie friendliness 55/100

WebAssembly/binaryen#7419 · 1 comment · Opened Mar 30, 2025
`scripts/fuzz_opt.py` can not be invoked from `scripts/` Open

Difficulty 2/5 1-3 hours Newbie friendliness 52/100

WebAssembly/binaryen#7417 · 1 comment · Opened Mar 28, 2025
Commandline tools and missing -o Open

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

WebAssembly/binaryen#7408 · Opened Mar 26, 2025
Difficulties with internally using refined types Open

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

WebAssembly/binaryen#7403 · 18 comments · Opened Mar 26, 2025
[wasm-merge] Does not print to stdout if `-o` is not specified Open

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

WebAssembly/binaryen#7397 · 4 comments · Opened Mar 25, 2025
StringLifting? Open

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

WebAssembly/binaryen#7370 · 4 comments · Opened Mar 13, 2025
wasm2js: support multiple tables Open

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

WebAssembly/binaryen#7358 · 3 comments · 2 reactions · Opened Mar 8, 2025
`wasm-opt -Oz` takes an inordinate amount of time Open

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

WebAssembly/binaryen#7319 · 11 comments · Opened Feb 24, 2025
undefined asyncify_get_state Open

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

WebAssembly/binaryen#7317 · 3 comments · Opened Feb 24, 2025
Avoid hosting allocations (especially array allocations) out of conditional paths Open

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

WebAssembly/binaryen#7304 · 2 comments · Opened Feb 20, 2025
[C API] Some BinaryenString* functions declared in binaryen-c.h without implementation Open

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

WebAssembly/binaryen#7301 · 3 comments · Opened Feb 19, 2025
NaN flip a sign bit on ARM(el) Open

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

WebAssembly/binaryen#7291 · 2 comments · Opened Feb 12, 2025
BinaryenAddFunctionImport lost internalName on export, is this intentional? Open

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

WebAssembly/binaryen#7272 · Opened Feb 3, 2025
How to get a call stack when wasm-ctor-eval stops? Open

interpreter

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

WebAssembly/binaryen#7255 · 6 comments · Opened Jan 30, 2025
Silence some error output in the presence of multi-step commands Open

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

WebAssembly/binaryen#7215 · 2 comments · Opened Jan 15, 2025

WebAssembly/binaryen

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