Introduction
After listening to Postman’s growth in ten years, did you wonder why it has such growth? Let us know some of the reasons behind that.
Postman allows writing test scripts, automating workflows with the help of a collection runner, capturing HTTPS requests, and forming connections. These have been made possible by using some of its features such as APIs, Requests’ Authorization, and Grouping requests. Grouping Requests require collections, Data Visualization, Analyzing API performance, Monitoring test runs, Defining API, etc. Also, it offers options for Team Collaboration, Development, and API publishing.

In this blog, we will learn about the process of capturing HTTPS Traffic Requests in different operating systems. We will also learn some aspects of enhanced capturing https techniques.
Capturing HTTPS Traffic in Postman
The Postman’s built-in proxy is used for several purposes, such as Capturing Request Data, Capturing HTTPS Traffic, Inspecting HTTPS Communication, etc. This blog will focus mainly on Capturing HTTPS Traffic in Postman.
Firstly, set up the Proxy in Postman. To capture secure HTTP Traffic, you must install the postman-proxy-ca.crt certificate on your device.

Follow the instructions below to proceed further and allow capturing on different Operating Systems.
Windows

Installing OpenSSL Module on Windows
The OpenSSL Module is used to generate certificate-key pairs. Also, for Postman to be able to generate the postman-proxy-ca.crt certificate, the OpenSSL Module must be installed on your device and accessible through the command line.
The OpenSSL v1.1.1 installer must be downloaded and installed for your operating system. The reason we should be specific about this version is that later versions of OpenSSL are not supported at this time.
Before installing, make sure that OpenSSL DLLs files are copied to the OpenSSL binaries (/bin) directory as a part of your pre-preparation.
To install the OpenSSL Module properly, follow these steps.
☘️ In the Start Menu, search for and open the Environment Variables using System Properties Window.
☘️ Select the path under User variables and click on Edit.
☘️ Please browse through the system’s storage, find your directory, and select it. The path for the directory is mentioned below.
This PC > Local Disk (C:) > Program Files > OpenSSL-Win64 > bin
☘️ To add the folder directory, select ok. After that, confirm the changes and close all the remaining windows.
☘️ To confirm the installation, enter the openssl version on the command line. The output similar to OpenSSL 1.1.1l 24 Aug 2021 confirms the successful installation of the OpenSSL Module.
Installing the Security Certificate
As we already learned that OpenSSL Module is mandatory before installing the security certificate, make sure that you have installed it. In case of any doubt, you can refer to a section of this article above discussing the installation of the OpenSSL Module.
To install the security certificate, follow the steps below.
🌱 In Windows File Explorer, open the %APPDATA%\Postman\proxy folder. Usually, the folder will be located at C:\Users\<user>\AppData\Roaming\Postman\proxy.
🌱 Right-click on the postman-proxy-ca.crt file and select Install Certificate.
🌱 Select Local Machine and grant Administrator permissions. Then, select Yes to confirm the actions.
🌱 Select Place all certificates in the following store and click on Browse.
🌱 After that, select Trusted Root Certification Authorities and click on Ok.
🌱 Select Next and click on Finish to complete the process.
🌱 The certificate is imported. Now, Restart the Postman.
MacOS

For MacOS, OpenSSL is already installed, so there is no need to setup again. You are required to follow the steps further to complete the procedure.
🌸 From the macOS Finder, open the ~/Library/Application Support/Postman/proxy folder.
🌸 Open the postman-proxy-ca.crt file by double-clicking on it.
🌸 In the Keychain list, select System and then click on Add. Enter the password for confirming actions.
🌸 From the Keychain Access, open the imported Postman Certificate by double-clicking on it.
🌸 Expand the Trust Section and select Always Trust option. Selecting Always Trust option is necessary to make SSL Layer work. Make sure it is always selected.
🌸 Now, close the Certificate Window. Enter the system password for settings updation.
CentOS and Red Hat Enterprise Linux

OpenSSL is typically installed for Linux, so there is no need to setup again. You are required to follow the steps further to complete the procedure.
🍄 Copy the security certificate file, that is, postman-proxy-ca.crt certificate file from ~/.config/Postman/proxy
to the /etc/pki/ca-trust/source/anchors/ directory.
sudo cp ~/.config/Postman/proxy/postman-proxy-ca.crt /etc/pki/ca-trust/source/anchors/
🍄 To complete the installation, run the command below.
sudo update-ca-trust extract
Ubuntu

🌷 Using the command below, create the directory for the CA Certificate.
sudo mkdir -p /usr/share/ca-certificates/extra
🌷 Copy the security certificate file, postman-proxy-ca.crt, to the new folder using the command below.
sudo cp ~/.config/Postman/proxy/postman-proxy-ca.crt /usr/share/ca-certificates/extra/postman-proxy-ca.crt
🌷 Now, add the certificate to the system using the commands below.
sudo dpkg-reconfigure ca-certificates
sudo update-ca-certificates
iOS

🌱To the iOS device, download the security certificate, that is, the postman-proxy-ca.crt certificate. You can find the certificate file on your computer in the locations given below.
macOS - ~/Library/Application Support/Postman/proxy
Windows - C:\Users\<user>\AppData\Roaming\Postman\proxy
Linux - ~/.config/Postman/proxy
🌱 Open the Profile Downloaded option of the Settings section.
🌱 Select Install and enter the passcode to proceed.
🌱 Read the security warning document and select Install.
🌱 After the Installation, select Done.
🌱 Go to settings, select General, About, and then go to Certificate Trust Settings.
🌱 Enable full trust for the root certificate and click on Continue to complete installation.
Android

☘️ To the Android device, download the security certificate, that is, the postman-proxy-ca.crt certificate. You can find the certificate file on your computer in the locations given below.
macOS - ~/Library/Application Support/Postman/proxy
Windows - C:\Users\<user>\AppData\Roaming\Postman\proxy
Linux - ~/.config/Postman/proxy
☘️ Now, open the Settings app and select the Security section. Under that section, go for Encryption & Credentials option.
☘️ Choose Install a Certificate and select the CA Certificate option.
☘️ Read up on the security warning document and select Install anyway.
☘️ Browse for and select the postman-proxy-ca.crt certificate file. You will receive a message of installation. You can now capture the HTTPS Traffic.
Troubleshooting Certificate Issues
If you are facing issues installing the security certificate or the certificate is not behaving expected, there is an error. To troubleshoot those issues, you need to follow the steps mentioned below.
🥀 Ensure that you are running Postman version 9.1 or later.
🥀 On the computer where you have installed the certificate, delete the folder. You can find the location of the certificate from the given options below.
macOS - ~/Library/Application Support/Postman/proxy
Windows - C:\Users\<user>\AppData\Roaming\Postman\proxy
Linux - ~/.config/Postman/proxy
🥀 Close and restart the Postman to regenerate the certificate.
🥀 Now, reinstall the certificate.