jart/cosmopolitan

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build-once run-anywhere c library

Stars: 21.3k
Forks: 777
Open beginner issues: 0
Indexed issues: 179

Dominant language: C
License: ISC
Last GitHub push: Jul 20, 2026
Latest indexed: Sep 18, 2026
Contributing guide: Contributing guide
Code of conduct: No code of conduct
Beginner labels: No beginner labels indexed
PR merge metrics: No merged PRs in 30d

Beginner friendly Everything

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179 open issues indexed

Bug: Crash after forked child exits Open

high severity

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

jart/cosmopolitan#1524 · 3 comments · Opened Sep 12, 2026
Windows: cosmocc cc1 blocks indefinitely (~0% CPU) on large C translation units, intermittently, at -O0 Open

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

jart/cosmopolitan#1522 · 1 reaction · Opened Sep 9, 2026
Windows: APE exit status is shifted left by 8 (exit code does not round-trip; failures read as success in POSIX shells) Open

Difficulty 4/5 3-5 days Newbie friendliness 68/100

jart/cosmopolitan#1521 · 1 comment · 1 reaction · Opened Sep 9, 2026
__program_executable_name is not always mapped when argc == 0 Open

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

jart/cosmopolitan#1520 · Opened Aug 28, 2026
Bug: redbean.dev is unaccessible due to Expired Cert Open

high severity

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

jart/cosmopolitan#1517 · 1 comment · 6 reactions · Opened Aug 26, 2026
Global macros naming conflicts Open

Difficulty 3/5 1-2 days Newbie friendliness 55/100

jart/cosmopolitan#1516 · 1 comment · Opened Aug 23, 2026
Graft native-compiler output into a pinned APE header template Open

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

jart/cosmopolitan#1512 · Opened Aug 18, 2026
Bug: HTTPS cert broken on website. Open

medium severity

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

jart/cosmopolitan#1504 · 6 comments · 16 reactions · Opened Jun 9, 2026
ReadMe still claims compatibility with Windows 8.x Open

Difficulty 1/5 Under an hour Newbie friendliness 88/100

jart/cosmopolitan#1503 · Opened May 28, 2026
Bug: pledge doesn't unveil nsswitch.conf Open

medium severity

Difficulty 3/5 1-2 days Newbie friendliness 55/100

jart/cosmopolitan#1499 · Opened May 22, 2026
Bug: a440 example is not compilable with cosmocc Open

low severity

Difficulty 1/5 Under an hour Newbie friendliness 78/100

jart/cosmopolitan#1495 · 5 comments · 1 reaction · Opened Apr 25, 2026
error: this ape binary only supports x86_64 Open

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

jart/cosmopolitan#1493 · 2 comments · Opened Mar 30, 2026
Bug: redbean crash on some files Open

critical severity

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

jart/cosmopolitan#1481 · Opened Feb 23, 2026
Feature Request: GetZipPaths to take in account overlay Open

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

jart/cosmopolitan#1479 · Opened Feb 17, 2026
Regression: Segfault on Linux x86_64 with `cosmo_dlopen` when calling foreign function Open

critical severity

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

jart/cosmopolitan#1478 · 1 comment · 1 reaction · Opened Feb 11, 2026
Bug: wait with no timeout with XNU times out after 72 minutes Open

medium severity

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

jart/cosmopolitan#1475 · Opened Feb 6, 2026
Bug: Cosmopolitan Python's `sys.platform` always returns 'linux' Open

low severity

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

jart/cosmopolitan#1462 · Opened Dec 30, 2025
Bug (with patch): redbean SIGSEGV when https certificates given on CLI (-C, -K) Open

medium severity

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

jart/cosmopolitan#1458 · 1 reaction · Opened Dec 19, 2025
Redbean: string multiply operator considered harmful Open

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

jart/cosmopolitan#1456 · 3 reactions · Opened Dec 15, 2025
Bug: ioctl for terminal settings not working as expected on Windows Open

medium severity

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

jart/cosmopolitan#1453 · Opened Nov 19, 2025
Feature Request: `redbean` auto-search for an available port if no port is provided. Open

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

jart/cosmopolitan#1450 · Opened Nov 15, 2025
Potential undefined behavior in `udiv128by64to64default()` due to `__builtin_clzll(0)` (related to GCC Bug 101175) Open

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

jart/cosmopolitan#1448 · Opened Nov 11, 2025
Feature Request: armv8l support Open

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

jart/cosmopolitan#1447 · 5 comments · Opened Nov 10, 2025
Bug: third_party/nsync/mu_semaphore_futex.c:72: unassert(futex_result == 0 Open

medium severity

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

jart/cosmopolitan#1446 · Opened Oct 23, 2025
Bug: -pg not working Open

medium severity

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

jart/cosmopolitan#1445 · 1 reaction · Opened Oct 5, 2025
Bug: cosmocc resulting binary can't boot Open

low severity

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

jart/cosmopolitan#1435 · 2 reactions · Opened Aug 11, 2025
Bug: Redbean's EncodeJSON escapes too much Open

medium severity

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

jart/cosmopolitan#1427 · Opened Jun 27, 2025
Bug: getcpu syscall error triggered on ARM when using unix.pledge() in Redbean Open

critical severity

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

jart/cosmopolitan#1418 · Opened May 15, 2025
Feature Request: Do not reuse different architecture version of temporary APE Loader on Darwin Open

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

jart/cosmopolitan#1409 · Opened May 1, 2025
Bug on Windows 10 bash: /C/cosmocc/bin/cosmocc: cannot execute: required file not found Open

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

jart/cosmopolitan#1406 · 1 comment · Opened Apr 23, 2025
Support for powerpc, riscv etc. Open

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

jart/cosmopolitan#1405 · 11 comments · Opened Apr 23, 2025
Bug: Redbean may send 2 contradicting Content-Encoding headers Open

high severity

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

jart/cosmopolitan#1403 · Opened Apr 21, 2025
Bug (redbean docs): documentation link to lsqlite3 docs incorrect. Open

Difficulty 1/5 Under an hour Newbie friendliness 65/100

jart/cosmopolitan#1402 · 1 comment · Opened Apr 18, 2025
Idea: uvfile (`uv` + embedded Python script, similar to llamafile) Open

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

jart/cosmopolitan#1396 · 2 comments · 2 reactions · Opened Apr 12, 2025
Feature Request: allow to seed Lemur64 in redbean Open

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

jart/cosmopolitan#1393 · Opened Apr 4, 2025
Bug: redbean.dev mentions removed ASAN support Open

low severity

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

jart/cosmopolitan#1391 · Opened Mar 28, 2025
Bug: cosmocc Segmentation fault with 64k PAGESIZE Open

medium severity

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

jart/cosmopolitan#1385 · Opened Mar 14, 2025
Bug: Cannot include `windowsesque` header into a cpp file Open

medium severity

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

jart/cosmopolitan#1380 · Opened Mar 6, 2025
Bug: doesn't play well with `sudo` (infinite forking?) Open

medium severity

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

jart/cosmopolitan#1379 · Opened Mar 3, 2025
Bug: unzip does not recognize `--` "option" Open

medium severity

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

jart/cosmopolitan#1378 · 1 comment · Opened Mar 3, 2025
Bug: Redbean demo crashes on startup on MacOS Open

medium severity

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

jart/cosmopolitan#1377 · 1 comment · Opened Mar 2, 2025
Feature Request: Implement named pipes Open

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

jart/cosmopolitan#1376 · 1 reaction · Opened Mar 2, 2025
why `cosmocc: fatal error: -march=native can't be used when building fat binaries` Open

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

jart/cosmopolitan#1374 · Opened Feb 27, 2025
Bug: Empty C file leads to a `tr` binary Open

medium severity

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

jart/cosmopolitan#1362 · 1 comment · 1 reaction · Opened Feb 6, 2025
Add a checksum file to `cosmo.zip` Open

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

jart/cosmopolitan#1360 · 1 reaction · Opened Jan 31, 2025
Bug: clang unsupported flag '-fschedule-insns2' added when `-fomit-frame-pointer` is passed Open

low severity

Difficulty 1/5 Under an hour Newbie friendliness 45/100

jart/cosmopolitan#1359 · Opened Jan 25, 2025
Bug: `df` cannot read table of mounted file systems on macos Open

contributions welcome medium severity

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

jart/cosmopolitan#1356 · 5 comments · Opened Jan 21, 2025
arc4random Open

accepted

jart/cosmopolitan#1343 · 5 comments · 1 assignee · Opened Dec 27, 2024
Bug: redbean: iterating unix.opendir can lead to random crashes with SIGSEGV SIGV_ACCERR Open

medium severity

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

jart/cosmopolitan#1337 · 3 comments · Opened Dec 14, 2024
Bug: unsupported -v option by cosmocc Open

low severity

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

jart/cosmopolitan#1316 · 3 comments · Opened Oct 15, 2024

jart/cosmopolitan

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