December 04, 2017

Add mapping to your application with Leaflet.js

Hey, before you start reading! I am in the market, looking for new freelance employment opportunities. If you need assistance on any of your ASP.NET Core projects, I am available for hire for freelance work.

When adding mapping to your application, the most common mapping libraries developers seem to use is either Mapbox or Google Maps. Both of these are great options, but both have limited free tier usage. Once you go past the free tier usage limit or you place the map behind a login, you start paying.

And the costs can mount up quickly.

There is however a free alternative available in OpenStreetMap. You can use their maps for free as long as you comply with their license. This basically amounts to give credit to the OpenStreetMap contributors in the corner of the map.

osm attribution example

One of the best JavaScript libraries for OpenStreetMap I have come across so far is Leaflet. The folks at Mapbox even use Leaflet as the basis for their own Mapbox.js library.

Get started with Leaflet

To get started with Leaflet, include the CSS file in the <head> section of your web page:

<link rel="stylesheet" href=""

And include the JavaScript file after the CSS (best somewhere near the bottom of the document before closing the body tag):

<!-- place near the bottom of the document body -->
<script src=""

Now add a div element to your document and give it an id, e.g. map:

 <div id="map"></div>

You will also need to give the div a height, so add the following CSS to your page:

#map { 
    height: 300px; 

or if you want to make the map full-screen, you can add the following CSS:

body { margin:0; padding:0; }
#map { position:absolute; top:0; bottom:0; width:100%; }

Finally you can create an instance of the map, setting the initial latitude to 13.7542, longitude to 100.493 and zoom level to 12. Then, add the OpenStreetMap tile layer to the map, with the proper attribution as per the OpenStreetMap license:

    var map ='map')
        .setView([13.7542, 100.493], 12);

    L.tileLayer('http://{s}{z}/{x}/{y}.png', {
        attribution: '&copy; <a href="">OpenStreetMap</a> contributors'

With that you will have a proper map being displayed:

leaflet map

Other tile sources

You can also use other tile sources to give your map a different style. You can for example go for a more elegant black-and-white map:

var map ='map')
  .setView([13.7542, 100.493], 12);

L.tileLayer('http://{s}{z}/{x}/{y}.png', {
	attribution: '&copy; <a href="">OpenStreetMap</a>'

leaflet map bw

Or how about a water color one:

var map ='map')
  .setView([13.7542, 100.493], 12);

L.tileLayer('https://stamen-tiles-{s}{z}/{x}/{y}.{ext}', {
	attribution: 'Map tiles by <a href="">Stamen Design</a>, <a href="">CC BY 3.0</a> &mdash; Map data &copy; <a href="">OpenStreetMap</a>',
	subdomains: 'abcd',
	minZoom: 1,
	maxZoom: 16,
	ext: 'png'

leaflet map watercolor

For more information on the available tile providers and samples, you can have a look at the Leaflet Providers GitHub page.

Learn more

To learn more, you can go through their Tutorials and Documentation. There is also a wide range of plugins available to add functionaly such as Marker Clustering, Heatmaps, etc.

Leaflet, along with OpenStreetMaps, is definitely a very good, free alternative which you can use instead of the more expensive commercial options like Mapbox, Google Maps and others.

Source Code

Not much in terms of external source code to include for this blog post, but here is the Pen I used for the screenshots in this blog post.

Follow me on Twitter @jerriepelser for tweets about coding and building a Saas.