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Go – HTTP ServeContent Function in Go

In this article, we will explore the http ServeContent function in Go net/http package in detail, along with examples.


The http.ServeContent function is a powerful feature in the Go programming language (also known as Golang) for serving files or content over HTTP. It simplifies the process of serving static files, handling caching, and managing partial content requests, such as when streaming large files or resuming downloads. In this article, we will discuss the http.ServeContent function in Go, provide examples, and delve into its usage and details.

Understanding the http.Serve Function

The http.ServeContent function is part of the net/http package in the Go standard library. Its primary purpose is to serve content over HTTP by generating appropriate responses, including handling conditional requests, setting headers, and managing partial content. The function signature is:

func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker)
  • w (ResponseWriter): The ResponseWriter interface that enables you to write the HTTP response.
  • req (*Request): A pointer to the current HTTP request being processed.
  • name (string): The name of the file being served, used to set the Content-Type and Content-Disposition headers.
  • modtime (time.Time): The modification time of the content. If non-zero, it is used to set the Last-Modified header and handle If-Modified-Since and If-Unmodified-Since conditional requests.
  • content (io.ReadSeeker): An interface that represents the content to be served. It must implement both io.Reader and io.Seeker interfaces.

Using http.ServeContent in Go

Here’s an example of using http.ServeContent to create a simple HTTP server that listens on port 8080 and serves a text file:

package main

import (

func main() {
	http.HandleFunc("/", serveContentHandler)
	http.ListenAndServe(":8080", nil)

func serveContentHandler(w http.ResponseWriter, r *http.Request) {
	file, err := os.Open("example.txt")
	if err != nil {
		http.Error(w, "File not found", http.StatusNotFound)
	defer file.Close()

	fileInfo, err := file.Stat()
	if err != nil {
		http.Error(w, "Internal server error", http.StatusInternalServerError)

	http.ServeContent(w, r, fileInfo.Name(), fileInfo.ModTime(), file)

In this example, we define a serveContentHandler function that will be called whenever a request is made to the root path (“/”). The handler opens the “example.txt” file using the os.Open function, retrieves its FileInfo using the Stat method, and then serves the content using the http.ServeContent function.

The http.ServeContent function automatically takes care of setting the appropriate response headers, handling conditional requests, and managing partial content based on the provided parameters.

Handling Partial Content Requests

One of the key features of http.ServeContent is its ability to handle partial content requests (HTTP Range requests). If a client sends a request with the “Range” header, the function will automatically serve the requested byte range and set the appropriate “Content-Range” and “Accept-Ranges” headers.

This feature is particularly useful for serving large files, as it allows clients (such as web browsers) to resume interrupted downloads or stream multimedia content more efficiently.


The http.ServeContent function in Go is a powerful feature for serving static files or content over HTTP. By managing various HTTP headers and efficiently handling partial content requests, it helps you create robust and performant web applications. Don’t hesitate to explore the Go standard library further and experiment with the various features it provides to enhance your web applications’ capabilities.

To check more Go related articles. Pls click given below link:

Posted in golang, net, packages

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