Ranked by how they treat first pull requests
The most beginner-friendly C open source projects
Projects that merge pull requests from outside contributors and answer them quickly: the two things a newcomer cannot see before sending one.
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1. freebsd/atf C
Libraries to write tests in C, C++ and shell
100% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 148 stars
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Self-contained Shadowsocks implementation in C with libuv, asynchronous DNS, and portable static builds for Linux, macOS, Windows, and FreeBSD.
100% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 16,175 stars
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3. pkgxdev/pantry C
pkg manifests
94% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 198 stars
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4. dolthub/doltlite C
DoltLite - Version Controlled SQLite
100% of outside PRs merged Maintainers usually reply within 1 day
6 open beginner issues 280 stars
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5. arkime/arkime C
Arkime is an open source, large scale, full packet capturing, indexing, and database system.
100% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 7,495 stars
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6. nanomsg/nng C
nanomsg-next-generation -- light-weight brokerless messaging
93% of outside PRs merged Maintainers usually reply within 1 day
2 open beginner issues 4,674 stars
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ImageMagick is a free, open-source software suite for creating, editing, converting, and displaying images. It supports 200+ formats and offers powerful command-line tools and APIs for automation, ...
92% of outside PRs merged Maintainers usually reply within 1 day
3 open beginner issues 17,529 stars
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Arm System Architecture: Architecture Compliance Suite
84% of outside PRs merged Maintainers usually reply within 1 day
2 open beginner issues 23 stars
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8-bit systems to ESP32 WiFi Multifunction Firmware
79% of outside PRs merged Maintainers usually reply within 1 day
6 open beginner issues 291 stars
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10. spacetelescope/hstcal C
Calibration for HST/WFC3, HST/ACS, and HST/STIS
76% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 12 stars
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11. SynoCommunity/spksrc C
Cross compilation framework to create native packages for the Synology's NAS
83% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 3,215 stars
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12. FreeRDP/FreeRDP C
FreeRDP is a free remote desktop protocol library and clients
65% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 13,739 stars
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13. OpenXiangShan/NEMU C
Super fast RISC-V ISA emulator for XiangShan processor
76% of outside PRs merged Maintainers usually reply within 1 day
6 open beginner issues 351 stars
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Spike, a RISC-V ISA Simulator
84% of outside PRs merged Maintainers usually reply within 1 day
3 open beginner issues 3,233 stars
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15. tuya/TuyaOpen C
Next-gen AI+IoT framework for T2/T3/T5AI/ESP32/and more – Fast IoT and AI Agent hardware integration
70% of outside PRs merged Maintainers usually reply within 1 day
2 open beginner issues 1,858 stars
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16. raysan5/raylib C
A simple and easy-to-use library to enjoy videogames programming
75% of outside PRs merged Maintainers usually reply within 1 day
2 open beginner issues 34,895 stars
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Driver and tools for controlling Lenovo Legion laptops in Linux including fan control and power mode.
98% of outside PRs merged Maintainers usually reply within 1 day
1 open beginner issue 3,390 stars
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18. JustVugg/colibri C
Run frontier MoE models on hardware you already own — pure C, zero deps, experts streamed from disk. Tiny engine, immense model. 🐦
73% of outside PRs merged Maintainers usually reply within 1 day
2 open beginner issues 36,626 stars
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19. libsdl-org/SDL C
Simple DirectMedia Layer
64% of outside PRs merged Maintainers usually reply within 1 day
5 open beginner issues 16,687 stars
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20. apache/nuttx C
Apache NuttX is a mature, real-time embedded operating system (RTOS)
85% of outside PRs merged Maintainers usually reply within 1 day
7 open beginner issues 4,039 stars
How this ranking works
Score = merge rate × reply speed. The merge rate is the share of pull requests from outside contributors (anyone who is not an owner, member or collaborator of the project, bots excluded) merged in the last 30 days, smoothed as (merged + 1) ÷ (sent + 2) so a few lucky merges do not outrank a long record. The reply speed is 1 ÷ (1 + the median number of days before a pull request gets its first reply from someone other than its author, or is merged). Bot comments do not count as replies.
Listed: projects with at least 10 outside pull requests in that window, at least one open beginner issue, at least 10 stars, a push in the last 180 days, not archived, and measured in the last 30 days.