diff --git a/R/shiny.R b/R/shiny.R
index a7cce4ea0a..50ac94bd2c 100644
--- a/R/shiny.R
+++ b/R/shiny.R
@@ -2126,6 +2126,51 @@ ShinySession <- R6Class(
           }
         })
       }
+    },
+
+    getUrl = function() {
+      req <- self$request
+
+      url <-
+        # Connect
+        req[["HTTP_X_RSC_REQUEST"]] %||%
+        req[["HTTP_RSTUDIO_CONNECT_APP_BASE_URL"]] %||%
+        # ShinyApps.io
+        if (!is.null(req[["HTTP_X_REDX_FRONTEND_NAME"]])) {
+          paste0("https://", req[["HTTP_X_REDX_FRONTEND_NAME"]])
+        }
+
+      if (is.null(url)) {
+        forwarded_host <- req[["HTTP_X_FORWARDED_HOST"]]
+        forwarded_port <- req[["HTTP_X_FORWARDED_PORT"]]
+
+        host <- if (!is.null(forwarded_host) && !is.null(forwarded_port)) {
+          paste0(forwarded_host, ":", forwarded_port)
+        } else {
+          req[["HTTP_HOST"]] %||% paste0(req[["SERVER_NAME"]], ":", req[["SERVER_PORT"]])
+        }
+
+        proto <- req[["HTTP_X_FORWARDED_PROTO"]] %||% req[["rook.url_scheme"]]
+
+        if (tolower(proto) == "http") {
+          host <- sub(":80$", "", host)
+        } else if (tolower(proto) == "https") {
+          host <- sub(":443$", "", host)
+        }
+
+        url <- paste0(
+          proto,
+          "://",
+          host,
+          req[["SCRIPT_NAME"]],
+          req[["PATH_INFO"]]
+        )
+      }
+
+      # Strip existing querystring, if any
+      url <- sub("\\?.*", "", url)
+
+      url
     }
   )
 )
diff --git a/man/runApp.Rd b/man/runApp.Rd
index 9daf245caf..ce4ff37a61 100644
--- a/man/runApp.Rd
+++ b/man/runApp.Rd
@@ -30,7 +30,10 @@ expression that produces a Shiny app object.
 \item{port}{The TCP port that the application should listen on. If the
 \code{port} is not specified, and the \code{shiny.port} option is set (with
 \code{options(shiny.port = XX)}), then that port will be used. Otherwise,
-use a random port.}
+use a random port between 3000:8000, excluding ports that are blocked
+by Google Chrome for being considered unsafe: 3659, 4045, 5060,
+5061, 6000, 6566, 6665:6669 and 6697. Up to twenty random
+ports will be tried.}
 
 \item{launch.browser}{If true, the system's default web browser will be
 launched automatically after the app is started. Defaults to true in
diff --git a/man/runExample.Rd b/man/runExample.Rd
index 89cc9969f9..c17a40ba56 100644
--- a/man/runExample.Rd
+++ b/man/runExample.Rd
@@ -19,7 +19,10 @@ list the available examples.}
 \item{port}{The TCP port that the application should listen on. If the
 \code{port} is not specified, and the \code{shiny.port} option is set (with
 \code{options(shiny.port = XX)}), then that port will be used. Otherwise,
-use a random port.}
+use a random port between 3000:8000, excluding ports that are blocked
+by Google Chrome for being considered unsafe: 3659, 4045, 5060,
+5061, 6000, 6566, 6665:6669 and 6697. Up to twenty random
+ports will be tried.}
 
 \item{launch.browser}{If true, the system's default web browser will be
 launched automatically after the app is started. Defaults to true in