How to develop over HTTPS on localhost

There are a number of reasons you may wish to use HTTPS as part of your web application development workflow:

Keep reading to find out how to set up SSL for local development.

Step 1: Generate a self-signed SSL certificate

Unless you are developing on a remote development environment with a static IP address, you won’t have a unique domain name that points to your development environment (and even if you are, you may not want or need one). Without a unique domain name, our only option for and SSL certificate is a self-signed one for local use only. Use this command to generate one:


Use the command below to generate your self-signed certificate and private key.

openssl req -x509 -out localhost.crt -keyout localhost.key -newkey rsa:2048 -nodes -subj '/CN=localhost' -extensions EXT -config <(printf "[req]\ndistinguished_name = dn\n[dn]\nCN=localhost\n[EXT]\nsubjectAltName=DNS:localhost\nkeyUsage=digitalSignature\nextendedKeyUsage=serverAuth")

Let’s pick that command apart. Feel free to skip to step 2 if you don’t care about the details.

The contents of the configuration are shown more readably below:

distinguished_name = dn

Step 2: Install and trust the certificate

Now your local operating system needs to know that the certificate is trustworthy. (Otherwise you’ll see a warning when you access https://localhost that the certificate is not trusted. This warning can be bypassed but trusting the certificate at the OS level gives a smoother development experience.)

For macOS, this can be achieved by following these steps:

  1. Open the Keychain Access app.
  2. Drag and drop your localhost.crt file onto the app.
  3. Right click on the new certificate entry and choose “Get Info”.
  4. Expand the “Trust” section of the Get Info dialog.
  5. For “Secure Sockets Layer (SSL)”, choose “Always Trust”.
  6. Close the dialog and input your password (or TouchID) to save the changes.

There should be a similar process for trusting the certificate in Windows and Linux.

If you’re working on a team, write some documentation for your teammates on how to do this (or point them to this article) so that new engineers can get up and running quickly.

Step 3: Configure your development server to use the certificate and private key

Lastly, your development server applications need to be updated to use the certificate and private key. This will be different for each language and framework. Here are some examples:

For Netlify, the netlify dev server can be configured to use your SSL certificate in development by adding the following to your netlify.toml file:

  certFile = "localhost.crt"
  keyFile = "localhost.key"

For Node.js servers, pass the key and cert options to https.createServer.

Once configured, you should be able to access your development server via HTTPS on localhost!

Additional reading