Files
cpp-httplib/docs-src/pages/en/tour/04-static-file-server.md
yhirose bef278e0d2 Fix docs pages that no longer match the code
Samples that did not compile or run as shown:
- res.user_data.get<T>() inside a generic lambda needs the `template`
  keyword; use explicit parameter types (tour 09, cookbook s15).
- listen() on a Unix domain socket fails with port 0 (tour 09, s22).
- "*.dev.local" is not a NO_PROXY pattern (c16).
- ssl_backend_error() holds a verify result, not an ERR_get_error()
  value, after a verification failure; decode each with the matching
  OpenSSL function (c18).
- The content provider's `length` is everything that remains, so the
  sample read the whole file in one call (s05).

Statements corrected:
- Client keep-alive is off by default; c14 is rewritten around
  set_keep_alive(true).
- Mounted files are looked up before GET handlers (tour 04, s04).
- Params keep insertion order, and to_string(Error::Connection) reads
  "Could not establish connection" (tour 02).
- A chunked provider ends with sink.done(), and post_routing_handler
  runs before the response is sent (tour 09).
- Timeouts surface as Error::Read; Error::Timeout comes from the stream
  API (c17). The max timeout cuts off the wait for the response only
  (c13). The progress callback needs Content-Length (c11).
- Encoding selection follows q-values, then Brotli, gzip, Zstd (s08),
  and the client compresses with the first of those it was built with
  (c15).
- stop() cuts a provider-driven response short (s19); a rejected
  content_reader already gets 400 or 413 (s07); user_data values must be
  copyable (s12); Client accepts a client certificate too (t04);
  on_message() is the fallback for every unhandled event and 204/403/404
  end reconnection (e04); the pong timeout takes two to three intervals
  and ends a waiting read() (w02).

In the LLM app tutorial, an uncaught exception does not crash the
server, so say what it does instead. Drop the server and client timeout
settings whose stated purpose, covering inference and download time,
they do not serve: those timeouts bound a single socket wait. Update
the llama.cpp server layout in chapter 7.
2026-10-08 20:39:13 -04:00

3.9 KiB

title, order
title order
Static File Server 4

cpp-httplib can serve static files too — HTML, CSS, images, you name it. No complicated configuration required. One call to set_mount_point() is all it takes.

The basics of set_mount_point

Let's jump right in. set_mount_point() maps a URL path to a local directory.

#include "httplib.h"
#include <iostream>

int main() {
    httplib::Server svr;

    svr.set_mount_point("/", "./html");

    std::cout << "Listening on port 8080..." << std::endl;
    svr.listen("0.0.0.0", 8080);
}

The first argument is the URL mount point. The second is the local directory path. In this example, requests to / are served from the ./html directory.

Let's try it out. First, create an html directory and add an index.html file.

mkdir html
<!DOCTYPE html>
<html>
<head><title>My Page</title></head>
<body>
    <h1>Hello from cpp-httplib!</h1>
    <p>This is a static file.</p>
</body>
</html>

Compile and start the server.

g++ -std=c++17 -o server server.cpp -pthread
./server

Open http://localhost:8080 in your browser. You should see the contents of html/index.html. Visiting http://localhost:8080/index.html returns the same page.

You can also access it with the client code from the previous chapter, or with curl.

httplib::Client cli("http://localhost:8080");
auto res = cli.Get("/");
if (res) {
    std::cout << res->body << std::endl;  // HTML is displayed
}
curl http://localhost:8080

Multiple mount points

You can call set_mount_point() as many times as you like. Each URL path gets its own directory.

svr.set_mount_point("/", "./public");
svr.set_mount_point("/assets", "./static/assets");
svr.set_mount_point("/docs", "./documentation");

A request to /assets/style.css serves ./static/assets/style.css. A request to /docs/guide.html serves ./documentation/guide.html.

Combining with handlers

Static file serving and routing handlers — the kind you learned about in the previous chapter — work side by side.

httplib::Server svr;

// API endpoint
svr.Get("/api/hello", [](const auto &, auto &res) {
    res.set_content(R"({"message":"Hello!"})", "application/json");
});

// Static file serving
svr.set_mount_point("/", "./public");

svr.listen("0.0.0.0", 8080);

The server looks for a file in ./public first and calls the handler when there is none. So the handler responds to /api/hello unless you put a file at ./public/api/hello.

Adding response headers

Pass headers as the third argument to set_mount_point() and they get attached to every static file response. This is great for cache control.

svr.set_mount_point("/", "./public", {
    {"Cache-Control", "max-age=3600"}
});

With this in place, the browser caches served files for one hour.

A Dockerfile for your static file server

The cpp-httplib repository includes a Dockerfile built for static file serving. We also publish a pre-built image on Docker Hub, so you can get up and running with a single command.

> docker run -p 8080:80 -v ./my-site:/html yhirose4dockerhub/cpp-httplib-server
Serving HTTP on 0.0.0.0:80
Mount point: / -> ./html
Press Ctrl+C to shutdown gracefully...
192.168.65.1 - - [22/Feb/2026:12:00:00 +0000] "GET / HTTP/1.1" 200 256 "-" "Mozilla/5.0 ..."
192.168.65.1 - - [22/Feb/2026:12:00:00 +0000] "GET /style.css HTTP/1.1" 200 1024 "-" "Mozilla/5.0 ..."
192.168.65.1 - - [22/Feb/2026:12:00:01 +0000] "GET /favicon.ico HTTP/1.1" 404 152 "-" "Mozilla/5.0 ..."

Everything in your ./my-site directory gets served on port 8080. The access log follows the same format as NGINX, so you can see exactly what's happening.

What's next

You can now serve static files. A web server that delivers HTML, CSS, and JavaScript — built with this little code.

Next, let's encrypt your connections with HTTPS. We'll start by setting up a TLS library.

Next: TLS Setup