keel-http (`keel::http`)

keel-http is a lightweight, zero-STL-header C++20 HTTP/HTTPS and WebSocket client library built on top of keel and licensed under 0BSD.

Features

Featherweight Public Header (keel/http.h): Transitively includes only <cstddef>, <cstdint>, and <new> (verified by test_header_purity), keeping compile times minimal.
Native OS Backends (Zero Heavy Dependencies on Windows & WebAssembly):
- Windows: Native WinHTTP (winhttp.dll) with TLS 1.2/1.3, HTTP/2, and WinHttpWebSocket*.
- Linux / macOS: libcurl (CURL::libcurl) with connection pooling.
- WebAssembly (Emscripten): Browser emscripten_fetch and emscripten_websocket.
First-Class keel Types: Uses keel::String, keel::StringRef, keel::FixedString, keel::Array<u8>, and keel::SmallArray<HttpHeader, 8> (zero heap allocations for typical header lists), while interoperating seamlessly with std::string_view and std::span at API boundaries.
RFC 3986 URL Parser: Supports http, https, ws, and wss schemes, IPv4, IPv6 ([::1]), ports, and query strings.
Testable Interfaces: Provides IHttpClient and IWebSocketClient interfaces for deterministic mocking in unit tests.

cmake -B build
cmake --build build
ctest --test-dir build -C Debug --output-on-failure

Zero-Clause BSD (0BSD).