Using self-signed SSL certificates with Postman

This post is applicable to the Postman Chrome app only. If you're using the Mac app, head to our documentation for details on ignoring SSL errors.

Self-signed certificates are often used in testing and development environments to provide a layer of security for an API. As they are not verified by a trusted authority, accessing  an API endpoint with something like https://<ip> through the Postman Chrome App, would throw up an error like this:

Screen Shot 2016-06-30 at 16.24.19

With the legacy app, you could go to the root URL in Chrome and allow the browser to access URLs with self-signed certificates. But this doesn't work with the new packaged app. If you try to hit a URL with a self-signed SSL certificate, you would get a 500 error as Chrome would decline the certificate:

ssl_error

Turns out that there is a better solution to solve this a problem, and it also avoids adding an exception to Chrome every time you start the browser. This is how you do it:

  1. Go to the root URL in your browser. For ex. https://localhost
  2. Click on the lock icon on the top left in the URL bar.
  3. Open the Connection tab in the dropdown that comes up
  4. Click on certificate information

The dialog that comes up now depends on the operating system you are on. Chrome uses the underlying OS layer to handle SSL certificates.

Mac OS X

  1. In the dialog that comes up, click 'View Certificate', and drag the certificate icon to your desktop to create a *.cer file
    Screen Shot 2016-06-30 at 16.24.40
    Screen Shot 2016-06-30 at 16.24.46

  2. Double click on the file to open the OS X Keychain Access tool.

  3. Add the certificate to the System keychain and select "Always trust"
    Screen Shot 2016-06-30 at 16.30.05

  4. Once the certificate is added, double click it to open more details

  5. Expand the Trust item

  6. Select "Always trust"
    Screen Shot 2016-06-30 at 16.26.50
  7. Close Keychain Access and restart Chrome

Windows

  1. In the certificates window, go to the Details tab

ssl_win_2
2. Select Copy to File
3. Save the certificate file on your disk. Close the certificate window.

ssl_win_3
4. Go to Chrome > Settings, search for SSL (chrome://settings/search#ssl) and click on Manage certificates

ssl_win_4
5. Go to the Trusted Root Certification Authorities tab and click on import
6. Select the file you saved on your disk in step 3.

ssl_win_5
7. Close this window and restart Chrome.

Linux

  1. Go to the Details tab

ssl_linux_1
2. Select Export and save the file on your disk

ssl_linux_2
3. Go to Chrome > Settings, search for SSL (chrome://settings/search#ssl) and click on Manage certificates
4. Go into the Authorities tab

ssl_linux_3
5. Import the certificate
6. Restart Chrome

You should be able to fire requests to the endpoints validated by this certificate. The SSL warning will not show up in Chrome even if you restart the browser. Do make sure that you have verified the IP where the certificate comes from. This should only be done for verified IP addresses. This method also works for certificates for localhost. Make sure that the common name of the certificate while generating the certificate is localhost.

Let me know in the comments if you face any problems with this.