diff --git a/knowledge base/vivaldi.md b/knowledge base/vivaldi.md
new file mode 100644
index 0000000..731bd73
--- /dev/null
+++ b/knowledge base/vivaldi.md	
@@ -0,0 +1,12 @@
+# Vivaldi browser
+
+| URL                 | Ports      | Description                 |
+| ------------------- | ---------- | --------------------------- |
+| bifrost.vivaldi.com | 443, 15674 | Sync settings               |
+| login.vivaldi.com   | 443        | Login to the user's account |
+
+## Further readings
+
+- [Decoding network activity in Vivaldi]
+
+[decoding network activity in vivaldi]: https://vivaldi.com/blog/decoding-network-activity-in-vivaldi/
diff --git a/rules.lsrules b/rules.lsrules
index d644630..fd974b1 100644
--- a/rules.lsrules
+++ b/rules.lsrules
@@ -69,6 +69,22 @@
             "remote-hosts": "icons.bitwarden.net",
             "via": "/Applications/Bitwarden.app/Contents/Frameworks/Bitwarden Helper.app/Contents/MacOS/Bitwarden Helper"
         },
+        {
+            "action": "allow",
+            "notes": "Allow Firefox to gather information about certificates.",
+            "ports": "80",
+            "process": "/Applications/Firefox.app/Contents/MacOS/firefox",
+            "protocol": "tcp",
+            "remote-hosts": "ocsp.sca1b.amazontrust.com"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Firefox to gather information about certificates.",
+            "ports": "80",
+            "process": "/Applications/Firefox.app/Contents/MacOS/firefox",
+            "protocol": "tcp",
+            "remote-hosts": "ocsp.digicert.com"
+        },
         {
             "action": "allow",
             "notes": "Allow Firefox to check for captive portals.",
@@ -278,6 +294,14 @@
             "remote-hosts": "marketplace.visualstudio.com",
             "via": "/Applications/Visual Studio Code.app/Contents/Frameworks/Code Helper.app/Contents/MacOS/Code Helper"
         },
+        {
+            "action": "allow",
+            "notes": "Allow VS Code to sync the user's settings.",
+            "ports": "443",
+            "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
+            "protocol": "tcp",
+            "remote-hosts": "vscode-sync.trafficmanager.net"
+        },
         {
             "action": "allow",
             "notes": "Allow VS Code to look for updates.",
@@ -286,6 +310,14 @@
             "protocol": "tcp",
             "remote-hosts": "update.code.visualstudio.com"
         },
+        {
+            "action": "allow",
+            "notes": "Allow VS Code to download Terraform's extension.",
+            "ports": "443",
+            "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
+            "protocol": "tcp",
+            "remote-hosts": "checkpoint-api.hashicorp.com"
+        },
         {
             "action": "allow",
             "notes": "Allow VS Code to download repositories from Github.",
@@ -294,6 +326,14 @@
             "protocol": "tcp",
             "remote-hosts": "github.com"
         },
+        {
+            "action": "allow",
+            "notes": "Allow VS Code to sync with its servers.",
+            "ports": "443",
+            "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
+            "protocol": "tcp",
+            "remote-hosts": "api.github.com",
+        },
         {
             "action": "allow",
             "notes": "Allow VS Code to download repositories from Gitlab.",
@@ -308,6 +348,78 @@
             "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
             "remote-hosts": "dc.services.visualstudio.com",
             "via": "/Applications/Visual Studio Code.app/Contents/Frameworks/Code Helper.app/Contents/MacOS/Code Helper"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow VS Code to download extensions.",
+            "ports": "443",
+            "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
+            "protocol": "tcp",
+            "remote-domains": "gallery.vsassets.io"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow VS Code to download extensions.",
+            "ports": "443",
+            "process": "/Applications/Visual Studio Code.app/Contents/MacOS/Electron",
+            "protocol": "tcp",
+            "remote-domains": "gallerycdn.vsassets.io"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Vivaldi to securely sync with its servers.",
+            "ports": "443",
+            "process": "/Applications/Vivaldi.app/Contents/MacOS/Vivaldi",
+            "protocol": "tcp",
+            "remote-hosts": "bifrost.vivaldi.com"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Vivaldi to sync with its servers.",
+            "ports": "15674",
+            "process": "/Applications/Vivaldi.app/Contents/MacOS/Vivaldi",
+            "protocol": "tcp",
+            "remote-hosts": "bifrost.vivaldi.com"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Vivaldi to securely login into the user's account.",
+            "ports": "443",
+            "process": "/Applications/Vivaldi.app/Contents/MacOS/Vivaldi",
+            "protocol": "tcp",
+            "remote-hosts": "login.vivaldi.com"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Vivaldi to securely connect to websites.",
+            "ports": "443",
+            "process": "/Applications/Vivaldi.app/Contents/MacOS/Vivaldi",
+            "protocol": "tcp",
+            "remote": "any"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow Vivaldi to securely connect to websites.",
+            "ports": "443",
+            "process": "/Applications/Vivaldi.app/Contents/MacOS/Vivaldi",
+            "protocol": "udp",
+            "remote": "any"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow WhatsApp to authenticate.",
+            "ports": "443",
+            "process": "/Applications/WhatsApp.app/Contents/MacOS/WhatsApp",
+            "protocol": "tcp",
+            "remote-hosts": "web.whatsapp.com"
+        },
+        {
+            "action": "allow",
+            "notes": "Allow WhatsApp to securely download media.",
+            "ports": "443",
+            "process": "/Applications/WhatsApp.app/Contents/MacOS/WhatsApp",
+            "protocol": "tcp",
+            "remote-domains": "cdn.whatsapp.net"
         }
     ]
 }