A local server for saving HTML elements as PNG files.
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httpng - A local server for snapshotting HTML elements


Httpng is a local server that you can run if you want to use HTML5 & CSS3 to design but you want to export the page elements as PNGs. The server uses the html2canvas library to render the elements on the screen. Please see the limitations section of this README for more information about what can and cannot be rendered.

Httpng follows the rules of Semantic Versioning.


You can install httpng with RubyGems:

$ gem install httpng


To run httpng, simply change directories to where your HTML file resides and run the following command:

$ httpng

This will run a web server at localhost:7020. You can change the port by setting the --port or -p option on the command line. When opening the web page in your browser, be sure to add the file name after the host and port. For example, if your file name is my_page.html then open up http://localhost:7020/my_page.html and not just http://localhost:7020/.


The server automatically inserts the JavaScript tags required for httpng to work so just make sure your file includes <HTML> or <HEAD> and the file extension is html.

When you load your page then you should see a bar at the top that gives you a button to export your images.

To mark HTML elements for export, simply add a data-export="<name>" tag to the element like this:

<div style="border:1px solid black;" data-export="my_file">
  <!-- More code here... -->

When you export your images, this DIV will be exported as my_file.png in your output directory.

Output Directory

By default, httpng will export your files to the httpng-output/ directory relative to when you started the command from. To change the output directory, simply use the --output or -o arguments on the command line:

$ httpng -o /path/to/my_output_dir


There are a few limitations with HTTPNG:

  1. Text directly in the exported element will not render. For example, placing text in a DIV (<div>foo</div>) will not render but putting the text in a span or p will work: <div><span>foo</span></div>

  2. Any limitation of the html2canvas library: http://html2canvas.hertzen.com/.