wsServer - a very tiny WebSocket server library written in C


wsServer is a tiny, lightweight WebSocket server library written in C that intends to be easy to use, fast, hackable, and almost compliant to the RFC 6455.

The main features are:

  • Send/Receive Text and Binary messages
  • PING/PONG frames
  • Opening/Closing handshakes

See Autobahn report and the docs for an 'in-depth' analysis.


wsServer only requires a C99-compatible compiler, and optionally Doxygen to build the docs. The build process comes in two flavors: pure makefile or CMake.


The preferred way to build wsServer on Linux environments. This also automatically builds an example file or a ready-to-use fuzzy version (see here for details):

git clone
cd wsServer/

# Optionally, a user can also install wsServer into the system,
# either on default paths or by providing PATH or DESTDIR env
# vars to the makefile.

make install # Or make install DESTDIR=/my/folder/


CMake enables the user to easily build wsServer in others environments other than Linux and also allows the use of an IDE to build the project automatically. If that's your case:

git clone
cd wsServer/
mkdir build && cd build/
cmake ..
./send_receive # Waiting for incoming connections...

in both cases, a statically lib (libws.a) will be generated.

Why to complicate if things can be simple?

wsServer abstracts the idea of sockets and you only need to deal with three types of events defined:

/* New client. */
void onopen(int fd);

/* Client disconnected. */
void onclose(int fd);

/* Client sent a text message. */
void onmessage(int fd, const unsigned char *msg, size_t size, int type);

/* fd is the File Descriptor returned by accepted connection. */

this is all you need to worry about, nothing to think about return values in socket, accepting connections, and so on.

As a gift, each client is handled in a separate thread, so you will not have to worry about it.

A complete example (file.c)

A more complete example, including the html file, can be found in example/ folder, ;-).

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <ws.h>

void onopen(int fd)
    char *cli;
    cli = ws_getaddress(fd);
    printf("Connection opened, client: %d | addr: %s\n", fd, cli);

void onclose(int fd)
    char *cli;
    cli = ws_getaddress(fd);
    printf("Connection closed, client: %d | addr: %s\n", fd, cli);

void onmessage(int fd, const unsigned char *msg, size_t size, int type)
    char *cli;
    cli = ws_getaddress(fd);
    printf("I receive a message: %s (%zu), from: %s/%d\n", msg,
        size, cli, fd);

    ws_sendframe_txt(fd, "hello", false);
    ws_sendframe_txt(fd, "world", false);


int main()
    /* Register events. */
    struct ws_events evs;
    evs.onopen    = &onopen;
    evs.onclose   = &onclose;
    evs.onmessage = &onmessage;

    /* Main loop, this function never returns. */
    ws_socket(&evs, 8080);

    return (0);

to build the example above, just invoke: make examples.

SSL/TLS Support

wsServer does not currently support encryption. However, it is possible to use it in conjunction with Stunnel, a proxy that adds TLS support to existing projects. Just follow these four easy steps to get TLS support on wsServer.


wsServer is always open to the community and willing to accept contributions, whether with issues, documentation, testing, new features, bugfixes, typos... welcome aboard. Make sure to read the coding-style guidelines before sending a PR.

License and Authors

wsServer is licensed under GPLv3 License. Written by Davidson Francis and others contributors.