By the numbers

Data collected on 2026-04-30 from a clone of curl/curl at commit ddb30354f6 on master.

Size

xychart-beta horizontal
    title "Source lines (approx.) by area"
    x-axis "Lines (k)"
    y-axis ["lib/", "lib/vtls/", "lib/vquic/", "lib/vauth/", "lib/vssh/", "lib/curlx/", "src/", "include/curl/", "tests/", "docs/"]
    bar [110, 25, 16, 8, 23, 6, 35, 7, 200, 80]

(Line counts are rough; exclude headers from each subdirectory's bar where the area mostly grows from .c files.)

Area	.c/.h files
lib/ (excluding subdirs)	184 / 178
lib/vtls/	17 / 14
lib/vquic/	4 / 5
lib/vauth/	13 / 2
lib/vssh/	4 / 2
lib/curlx/	19 / 19
src/	43 / 45
include/curl/	0 / 12 + curl.h
docs/cmdline-opts/	~280 markdown files (one per option)
docs/libcurl/opts/	~340 markdown files (one per CURLOPT/CURLINFO/CURLMOPT/CURLSHOPT)
docs/examples/	129 example C programs
tests/data/	1968 numbered tests
.github/workflows/	17 workflow files

Aggregate: ~196k lines of C across lib/, src/, and include/. The total source tree (with docs and tests) is much larger; the tests/data/ directory alone has nearly 2k single-file tests.

The largest individual files:

File	Size
lib/vtls/openssl.c	171 KB
configure.ac	162 KB
lib/http.c	157 KB
lib/ftp.c	141 KB
lib/multi.c	128 KB
lib/vssh/libssh2.c	126 KB
lib/url.c	113 KB
src/tool_getparam.c	103 KB
lib/vtls/schannel.c	99 KB
lib/http2.c	97 KB
lib/vquic/curl_ngtcp2.c	96 KB
CMakeLists.txt	92 KB
lib/vssh/libssh.c	93 KB
lib/setopt.c	84 KB

Activity

Total commits in the repository: 38,547 (first commit imported in December 1999 from CVS history dating back to 1996; SVN/CVS-era history is preserved).

Commits in the last 90 days: 823. Recent monthly activity:

Month	Commits
2025-04	11
2025-05	199
2025-06	226
2025-07	286
2025-08	243
2025-09	276
2025-10	438
2025-11	410
2025-12	333
2026-01	288
2026-02	222
2026-03	357
2026-04	232 (partial)

(The pre-May-2025 activity in the table reflects the way this snapshot's git log was filtered, not historical truth — the project has been continuously active since 1996.)

Churn hot-spots (last 90 days)

File / Path	Touched commits
.github/workflows/linux.yml	54
tests/data/Makefile.am	49
lib/url.c	48
CMakeLists.txt	48
.github/workflows/http3-linux.yml	45
lib/http.c	44
.github/workflows/windows.yml	38
lib/vtls/openssl.c	36
lib/ftp.c	34
lib/multi.c	32
lib/curl_setup.h	32
src/tool_operate.c	29
lib/urldata.h	29
RELEASE-NOTES	28
configure.ac	27

Churn hot-spots by directory

Directory	Commits touching it (90d)
lib/	1312
docs/libcurl/opts/	297
docs/examples/	278
tests/data/	276
src/	237
.github/workflows/	234
lib/vtls/	230
tests/unit/	172
tests/libtest/	162

Bot-attributed commits

Commits in the last two years that include a Co-authored-by: <something>[bot] line: 0 out of 6,407.

curl is essentially un-touched by automated commit bots (no Dependabot, no GitHub Actions auto-PRs in the merge history). This is a lower bound: AI assistants used inline by contributors leave no trace. Treat this number as evidence that bot-authored commits are not part of the project's day-to-day flow, not a claim about AI tooling overall.

Test coverage by count

Test kind	Count
Functional tests	1968 (tests/data/test*)
Unit tests	~250 (tests/unit/unit*.c)
libtest programs	~600 (tests/libtest/lib*.c)
Type-check tests	a few dozen (tests/tunit/)
Fuzz harnesses	several (tests/fuzz/)

Tests are run on every PR across an extensive matrix in .github/workflows/linux.yml, macos.yml, windows.yml, and non-native.yml.

Public API surface

Surface	Approximate count
CURLOPT_* options	308
CURLINFO_* getinfo properties	~80
CURLMOPT_* multi options	~15
CURLSHOPT_* share options	~5
Public functions	~100
CURLcode error codes	~100
Supported URL schemes	28+

Per-subsystem snapshot

Subsystem	Files in lib/*	Largest file
Transfer engine	4	multi.c 128 KB
Connection management	7	url.c 113 KB
Connection filters	13 (cf-*.c)	cf-socket.c 69 KB
HTTP	11	http.c 157 KB
HTTP/2	1	http2.c 97 KB
HTTP/3 + QUIC	5	curl_ngtcp2.c 96 KB
TLS backends	8 backends + abstraction	openssl.c 171 KB
FTP	4	ftp.c 141 KB
SMTP/IMAP/POP3	3 + pingpong	smtp.c 61 KB / imap.c 68 KB
SSH (vssh)	2 backends	libssh2.c 126 KB
Authentication (vauth)	13	digest.c 33 KB
URL API	1	urlapi.c 56 KB
Cookies/HSTS/Alt-Svc	3	cookie.c 48 KB
MIME/forms	2	mime.c 62 KB
WebSocket	1	ws.c 62 KB

For "what does this subsystem do?", see the corresponding Systems and Features pages.