A Fast and Easy to use microframework for the web.

Description

Crow is a C++ microframework for running web services. It uses routing similar to Python's Flask which makes it easy to use. It is also extremely fast, beating multiple existing C++ frameworks as well as non C++ frameworks.

Features

• Easy Routing (similar to flask).
• Type-safe Handlers.
• Blazingly fast (see this benchmark and this benchmark).
• Built in JSON support.
• Mustache based templating library (crow::mustache).
• Header only library (single header file available).
• Middleware support for extensions.
• HTTP/1.1 and Websocket support.
• Multi-part request and response support.
• Uses modern C++ (11/14)

Still in development

• HTTP/2 support

Documentation

Available here.

Examples

Hello World

#include "crow.h"

int main()
{
    crow::SimpleApp app;

    CROW_ROUTE(app, "/")([](){
        return "Hello world";
    });

    app.port(18080).multithreaded().run();
}

JSON Response

CROW_ROUTE(app, "/json")
([]{
    crow::json::wvalue x;
    x["message"] = "Hello, World!";
    return x;
});

Arguments

CROW_ROUTE(app,"/hello/<int>")
([](int count){
    if (count > 100)
        return crow::response(400);
    std::ostringstream os;
    os << count << " bottles of beer!";
    return crow::response(os.str());
});

Handler arguments type check at compile time

// Compile error with message "Handler type is mismatched with URL paramters"
CROW_ROUTE(app,"/another/<int>")
([](int a, int b){
    return crow::response(500);
});

Handling JSON Requests

CROW_ROUTE(app, "/add_json")
.methods("POST"_method)
([](const crow::request& req){
    auto x = crow::json::load(req.body);
    if (!x)
        return crow::response(400);
    int sum = x["a"].i()+x["b"].i();
    std::ostringstream os;
    os << sum;
    return crow::response{os.str()};
});

More examples can be found here.

Setting Up / Building

Available here.

Attributions

Crow uses the following libraries.

http-parser (used for converting http strings to crow::request objects)

https://github.com/nodejs/http-parser

http_parser.c is based on src/http/ngx_http_parse.c from NGINX copyright
Igor Sysoev.

Additional changes are licensed under the same terms as NGINX and
copyright Joyent, Inc. and other Node contributors. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to
deal in the Software without restriction, including without limitation the
rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
IN THE SOFTWARE. 


qs_parse (used for reading query string parameters)

https://github.com/bartgrantham/qs_parse

Copyright (c) 2010 Bart Grantham
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.


TinySHA1 (used during the websocket handshake, not for security)

https://github.com/mohaps/TinySHA1

TinySHA1 - a header only implementation of the SHA1 algorithm. Based on the
implementation in boost::uuid::details

Copyright (c) 2012-22 SAURAV MOHAPATRA mohaps@gmail.com
Permission to use, copy, modify, and distribute this software for any purpose
with or without fee is hereby granted, provided that the above copyright 
notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, 
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 
LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.