diff --git a/DESCRIPTION b/DESCRIPTION
index adb80a01d..f88471cac 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -49,6 +49,7 @@ Imports:
   withr (>= 2.1.2)
 Suggests:
   aws.s3 (>= 0.3.21),
+  bs4Dash(>= 0.5.0),
   clustermq (>= 0.8.9),
   curl (>= 4.3),
   dplyr (>= 1.0.0),
@@ -60,6 +61,8 @@ Suggests:
   pkgload (>= 1.1.0),
   qs (>= 0.23.2),
   rstudioapi (>= 0.11),
+  shiny (>= 1.5.0),
+  shinycssloaders (>= 1.0.0),
   testthat (>= 3.0.0),
   torch (>= 0.1.0),
   usethis (>= 1.6.3),
diff --git a/NAMESPACE b/NAMESPACE
index b7b7efe71..b8f26ff87 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -255,6 +255,9 @@ export(tar_test)
 export(tar_traceback)
 export(tar_validate)
 export(tar_visnetwork)
+export(tar_watch)
+export(tar_watch_server)
+export(tar_watch_ui)
 export(tar_workspace)
 export(tar_workspaces)
 export(target_run_worker)
diff --git a/R/tar_watch.R b/R/tar_watch.R
new file mode 100644
index 000000000..b19b13323
--- /dev/null
+++ b/R/tar_watch.R
@@ -0,0 +1,238 @@
+# nocov start # Tested in tests/interactive/test-tar_watch.R
+#' @title Shiny app to watch the dependency graph.
+#' @export
+#' @description Calls [tar_visnetwork()] every few seconds.
+#' @details The controls of the app are in the left panel.
+#'   The `seconds` control is the number of seconds between
+#'   refreshes of the graph, and the other settings match
+#'   the arguments of [`tar_visnetwork()`].
+#' @return A Shiny app.
+#' @inheritParams tar_watch_ui
+#' @examples
+#' if (FALSE) { # Only run interactively.
+#' tar_dir({
+#' tar_script({
+#'   sleep_run <- function(...) {
+#'     Sys.sleep(10)
+#'   }
+#'   tar_pipeline(
+#'     tar_target(settings, sleep_run()),
+#'     tar_target(data1, sleep_run(settings)),
+#'     tar_target(data2, sleep_run(settings)),
+#'     tar_target(data3, sleep_run(settings)),
+#'     tar_target(model1, sleep_run(data1)),
+#'     tar_target(model2, sleep_run(data2)),
+#'     tar_target(model3, sleep_run(data3)),
+#'     tar_target(figure1, sleep_run(model1)),
+#'     tar_target(figure2, sleep_run(model2)),
+#'     tar_target(figure3, sleep_run(model3)),
+#'     tar_target(conclusions, sleep_run(c(figure1, figure2, figure3)))
+#'   )
+#' })
+#' px <- tar_make(callr_function = callr::r_bg)
+#' tar_watch(seconds = 10, outdated = FALSE, targets_only = TRUE)
+#' })
+#' }
+tar_watch <- function(
+  seconds = 5,
+  seconds_min = 1,
+  seconds_max = 100,
+  seconds_step = 1,
+  targets_only = FALSE,
+  outdated = TRUE,
+  label = NULL,
+  level_separation = 150,
+  height = "700px"
+) {
+  assert_package("bs4Dash")
+  assert_package("shiny")
+  assert_package("shinycssloaders")
+  assert_package("visNetwork")
+  assert_target_script()
+  assert_dbl(seconds, "seconds must be numeric.")
+  assert_dbl(seconds_min, "seconds_min must be numeric.")
+  assert_dbl(seconds_max, "seconds_max must be numeric.")
+  assert_dbl(seconds_step, "seconds_step must be numeric.")
+  assert_scalar(seconds, "seconds must have length 1.")
+  assert_scalar(seconds_min, "seconds_min must have length 1.")
+  assert_scalar(seconds_max, "seconds_max must have length 1.")
+  assert_scalar(seconds_step, "seconds_step must have length 1.")
+  seconds_min <- min(seconds_min, seconds)
+  seconds_max <- max(seconds_max, seconds)
+  seconds_step <- min(seconds_step, seconds_max)
+  ui <- tar_watch_app_ui(
+    seconds = seconds,
+    seconds_min = seconds_min,
+    seconds_max = seconds_max,
+    seconds_step = seconds_step,
+    targets_only = targets_only,
+    outdated = outdated,
+    label_tar_visnetwork = label,
+    level_separation = level_separation,
+    height = height
+  )
+  server <- function(input, output, session) {
+    tar_watch_server("tar_watch_id", height = height)
+  }
+  shiny::shinyApp(ui = ui, server = server)
+}
+
+tar_watch_app_ui <- function(
+  seconds,
+  seconds_min,
+  seconds_max,
+  seconds_step,
+  targets_only,
+  outdated,
+  label_tar_visnetwork,
+  level_separation,
+  height
+) {
+  body <- bs4Dash::bs4DashBody(
+    tar_watch_ui(
+      id = "tar_watch_id",
+      label = "tar_watch_label",
+      seconds = seconds,
+      seconds_min = seconds_min,
+      seconds_max = seconds_max,
+      seconds_step = seconds_step,
+      targets_only = targets_only,
+      outdated = outdated,
+      label_tar_visnetwork = label_tar_visnetwork,
+      level_separation = level_separation,
+      height = height
+    )
+  )
+  bs4Dash::bs4DashPage(
+    title = "",
+    body = body,
+    navbar = bs4Dash::bs4DashNavbar(controlbarIcon = NULL),
+    sidebar = bs4Dash::bs4DashSidebar(disable = TRUE)
+  )
+}
+
+#' @title Shiny module UI for tar_watch()
+#' @export
+#' @description Use `tar_watch_ui()` and [tar_watch_server()]
+#'   to include [tar_watch()] as a Shiny module in an app.
+#' @examples
+#' str(tar_watch_ui("my_id"))
+#' @return A Shiny module UI.
+#' @inheritParams shiny::moduleServer
+#' @inheritParams tar_watch_server
+#' @inheritParams tar_visnetwork
+#' @param label Label for the module.
+#' @param seconds Numeric of length 1,
+#'   default number of seconds between refreshes of the graph.
+#'   Can be changed in the app controls.
+#' @param seconds_min Numeric of length 1, lower bound of `seconds`
+#'   in the app controls.
+#' @param seconds_max Numeric of length 1, upper bound of `seconds`
+#'   in the app controls.
+#' @param seconds_step Numeric of length 1, step size of `seconds`
+#'   in the app controls.
+#' @param label_tar_visnetwork Character vector, `label` argument to
+#'   [tar_visnetwork()].
+tar_watch_ui <- function(
+  id,
+  label = "tar_watch_label",
+  seconds = 5,
+  seconds_min = 1,
+  seconds_max = 60,
+  seconds_step = 1,
+  targets_only = FALSE,
+  outdated = TRUE,
+  label_tar_visnetwork = NULL,
+  level_separation = 150,
+  height = "700px"
+) {
+  ns <- shiny::NS(id)
+  shiny::fluidRow(
+    shiny::column(
+      width = 4,
+      bs4Dash::bs4Card(
+        inputID = ns("control"),
+        title = "Control",
+        status = "primary",
+        closable = FALSE,
+        width = 12,
+        shiny::sliderInput(
+          ns("seconds"),
+          "seconds",
+          value = seconds,
+          min = seconds_min,
+          max = seconds_max,
+          step = seconds_step
+        ),
+        shiny::selectInput(
+          ns("targets_only"),
+          "targets_only",
+          choices = c("TRUE", "FALSE"),
+          selected = as.character(targets_only)
+        ),
+        shiny::selectInput(
+          ns("outdated"),
+          "outdated",
+          choices = c("TRUE", "FALSE"),
+          selected = as.character(outdated)
+        ),
+        shiny::selectInput(
+          ns("label"),
+          "label",
+          choices = c("time", "size", "branches"),
+          selected = as.character(label_tar_visnetwork),
+          multiple = TRUE
+        ),
+        shiny::sliderInput(
+          ns("level_separation"),
+          "level_separation",
+          value = as.numeric(level_separation),
+          min = 0,
+          max = 1000,
+          step = 10
+        )
+      )
+    ),
+    shiny::column(
+      width = 8,
+      bs4Dash::bs4Card(
+        inputID = ns("graph"),
+        title = "Graph",
+        status = "primary",
+        closable = FALSE,
+        width = 12,
+        shinycssloaders::withSpinner(
+          visNetwork::visNetworkOutput(ns("graph"), height = height)
+        )
+      )
+    )
+  )
+}
+
+#' @title Shiny module server for tar_watch()
+#' @export
+#' @description Use [tar_watch_ui()] and `tar_watch_server()`
+#'   to include [tar_watch()] as a Shiny module in an app.
+#' @return A Shiny module server.
+#' @inheritParams shiny::moduleServer
+#' @param height Character of length 1,
+#'   height of the `visNetwork` widget.
+#' @examples
+#' # tar_watch_server("my_id") # Only call inside an app.
+tar_watch_server <- function(id, height = "700px") {
+  shiny::moduleServer(
+    id,
+    function(input, output, session) {
+      output$graph <- visNetwork::renderVisNetwork({
+        shiny::invalidateLater(millis = 1000 * as.numeric(input$seconds))
+        tar_visnetwork(
+          targets_only = as.logical(input$targets_only),
+          outdated = as.logical(input$outdated),
+          label = as.character(input$label),
+          level_separation = as.numeric(input$level_separation)
+        )
+      })
+    }
+  )
+}
+# nocov end
diff --git a/_pkgdown.yml b/_pkgdown.yml
index 2739414e5..d24389ddc 100644
--- a/_pkgdown.yml
+++ b/_pkgdown.yml
@@ -51,6 +51,9 @@ reference:
   - '`tar_glimpse`'
   - '`tar_network`'
   - '`tar_visnetwork`'
+  - '`tar_watch`'
+  - '`tar_watch_server`'
+  - '`tar_watch_ui`'
 - title: Inspect
   contents:
   - '`tar_deps`'
diff --git a/inst/WORDLIST b/inst/WORDLIST
index 792b8ee68..65d423e46 100644
--- a/inst/WORDLIST
+++ b/inst/WORDLIST
@@ -286,6 +286,7 @@ toolkits
 traceback
 txtq
 UD
+UI
 un
 unexportable
 unhandled
diff --git a/man/tar_watch.Rd b/man/tar_watch.Rd
new file mode 100644
index 000000000..47d25ea9d
--- /dev/null
+++ b/man/tar_watch.Rd
@@ -0,0 +1,93 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tar_watch.R
+\name{tar_watch}
+\alias{tar_watch}
+\title{Shiny app to watch the dependency graph.}
+\usage{
+tar_watch(
+  seconds = 5,
+  seconds_min = 1,
+  seconds_max = 100,
+  seconds_step = 1,
+  targets_only = FALSE,
+  outdated = TRUE,
+  label = NULL,
+  level_separation = 150,
+  height = "700px"
+)
+}
+\arguments{
+\item{seconds}{Numeric of length 1,
+default number of seconds between refreshes of the graph.
+Can be changed in the app controls.}
+
+\item{seconds_min}{Numeric of length 1, lower bound of \code{seconds}
+in the app controls.}
+
+\item{seconds_max}{Numeric of length 1, upper bound of \code{seconds}
+in the app controls.}
+
+\item{seconds_step}{Numeric of length 1, step size of \code{seconds}
+in the app controls.}
+
+\item{targets_only}{Logical, whether to restrict the output to just targets
+(\code{FALSE}) or to also include imported global functions and objects.}
+
+\item{outdated}{Logical, whether to show colors to distinguish outdated
+targets from up-to-date targets. (Global functions and objects
+still show these colors.) Looking for outdated targets
+takes a lot of time for large pipelines with lots of branches,
+and setting \code{outdated} to \code{FALSE} is a nice way to speed up the graph
+if you only want to see dependency relationships and build progress.}
+
+\item{label}{Label for the module.}
+
+\item{level_separation}{Numeric of length 1,
+\code{levelSeparation} argument of \code{visNetwork::visHierarchicalLayout()}.
+Controls the distance between hierarchical levels.
+Consider changing the value if the aspect ratio of the graph
+is far from 1. If \code{level_separation} is \code{NULL},
+the \code{levelSeparation} argument of \code{visHierarchicalLayout()}
+defaults to \code{150}.}
+
+\item{height}{Character of length 1,
+height of the \code{visNetwork} widget.}
+}
+\value{
+A Shiny app.
+}
+\description{
+Calls \code{\link[=tar_visnetwork]{tar_visnetwork()}} every few seconds.
+}
+\details{
+The controls of the app are in the left panel.
+The \code{seconds} control is the number of seconds between
+refreshes of the graph, and the other settings match
+the arguments of \code{\link[=tar_visnetwork]{tar_visnetwork()}}.
+}
+\examples{
+if (FALSE) { # Only run interactively.
+tar_dir({
+tar_script({
+  sleep_run <- function(...) {
+    Sys.sleep(10)
+  }
+  tar_pipeline(
+    tar_target(settings, sleep_run()),
+    tar_target(data1, sleep_run(settings)),
+    tar_target(data2, sleep_run(settings)),
+    tar_target(data3, sleep_run(settings)),
+    tar_target(model1, sleep_run(data1)),
+    tar_target(model2, sleep_run(data2)),
+    tar_target(model3, sleep_run(data3)),
+    tar_target(figure1, sleep_run(model1)),
+    tar_target(figure2, sleep_run(model2)),
+    tar_target(figure3, sleep_run(model3)),
+    tar_target(conclusions, sleep_run(c(figure1, figure2, figure3)))
+  )
+})
+px <- tar_make(callr_function = callr::r_bg)
+tar_watch(seconds = 10, outdated = FALSE, targets_only = TRUE)
+})
+}
+}
diff --git a/man/tar_watch_server.Rd b/man/tar_watch_server.Rd
new file mode 100644
index 000000000..fa34c24fd
--- /dev/null
+++ b/man/tar_watch_server.Rd
@@ -0,0 +1,25 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tar_watch.R
+\name{tar_watch_server}
+\alias{tar_watch_server}
+\title{Shiny module server for tar_watch()}
+\usage{
+tar_watch_server(id, height = "700px")
+}
+\arguments{
+\item{id}{An ID string that corresponds with the ID used to call the module's
+UI function.}
+
+\item{height}{Character of length 1,
+height of the \code{visNetwork} widget.}
+}
+\value{
+A Shiny module server.
+}
+\description{
+Use \code{\link[=tar_watch_ui]{tar_watch_ui()}} and \code{tar_watch_server()}
+to include \code{\link[=tar_watch]{tar_watch()}} as a Shiny module in an app.
+}
+\examples{
+# tar_watch_server("my_id") # Only call inside an app.
+}
diff --git a/man/tar_watch_ui.Rd b/man/tar_watch_ui.Rd
new file mode 100644
index 000000000..d66ae1ac8
--- /dev/null
+++ b/man/tar_watch_ui.Rd
@@ -0,0 +1,73 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/tar_watch.R
+\name{tar_watch_ui}
+\alias{tar_watch_ui}
+\title{Shiny module UI for tar_watch()}
+\usage{
+tar_watch_ui(
+  id,
+  label = "tar_watch_label",
+  seconds = 5,
+  seconds_min = 1,
+  seconds_max = 60,
+  seconds_step = 1,
+  targets_only = FALSE,
+  outdated = TRUE,
+  label_tar_visnetwork = NULL,
+  level_separation = 150,
+  height = "700px"
+)
+}
+\arguments{
+\item{id}{An ID string that corresponds with the ID used to call the module's
+UI function.}
+
+\item{label}{Label for the module.}
+
+\item{seconds}{Numeric of length 1,
+default number of seconds between refreshes of the graph.
+Can be changed in the app controls.}
+
+\item{seconds_min}{Numeric of length 1, lower bound of \code{seconds}
+in the app controls.}
+
+\item{seconds_max}{Numeric of length 1, upper bound of \code{seconds}
+in the app controls.}
+
+\item{seconds_step}{Numeric of length 1, step size of \code{seconds}
+in the app controls.}
+
+\item{targets_only}{Logical, whether to restrict the output to just targets
+(\code{FALSE}) or to also include imported global functions and objects.}
+
+\item{outdated}{Logical, whether to show colors to distinguish outdated
+targets from up-to-date targets. (Global functions and objects
+still show these colors.) Looking for outdated targets
+takes a lot of time for large pipelines with lots of branches,
+and setting \code{outdated} to \code{FALSE} is a nice way to speed up the graph
+if you only want to see dependency relationships and build progress.}
+
+\item{label_tar_visnetwork}{Character vector, \code{label} argument to
+\code{\link[=tar_visnetwork]{tar_visnetwork()}}.}
+
+\item{level_separation}{Numeric of length 1,
+\code{levelSeparation} argument of \code{visNetwork::visHierarchicalLayout()}.
+Controls the distance between hierarchical levels.
+Consider changing the value if the aspect ratio of the graph
+is far from 1. If \code{level_separation} is \code{NULL},
+the \code{levelSeparation} argument of \code{visHierarchicalLayout()}
+defaults to \code{150}.}
+
+\item{height}{Character of length 1,
+height of the \code{visNetwork} widget.}
+}
+\value{
+A Shiny module UI.
+}
+\description{
+Use \code{tar_watch_ui()} and \code{\link[=tar_watch_server]{tar_watch_server()}}
+to include \code{\link[=tar_watch]{tar_watch()}} as a Shiny module in an app.
+}
+\examples{
+str(tar_watch_ui("my_id"))
+}
diff --git a/tests/interactive/test-tar_watch.R b/tests/interactive/test-tar_watch.R
new file mode 100644
index 000000000..a9e861214
--- /dev/null
+++ b/tests/interactive/test-tar_watch.R
@@ -0,0 +1,23 @@
+library(targets)
+tar_script({
+  sleep_run <- function(...) {
+    Sys.sleep(10)
+  }
+  tar_pipeline(
+    tar_target(settings, sleep_run()),
+    tar_target(data1, sleep_run(settings)),
+    tar_target(data2, sleep_run(settings)),
+    tar_target(data3, sleep_run(settings)),
+    tar_target(model1, sleep_run(data1)),
+    tar_target(model2, sleep_run(data2)),
+    tar_target(model3, sleep_run(data3)),
+    tar_target(figure1, sleep_run(model1)),
+    tar_target(figure2, sleep_run(model2)),
+    tar_target(figure3, sleep_run(model3)),
+    tar_target(conclusions, sleep_run(c(figure1, figure2, figure3)))
+  )
+})
+px <- tar_make(callr_function = callr::r_bg)
+tar_watch(seconds = 10, outdated = FALSE, targets_only = TRUE)
+tar_destroy()
+unlink("_targets.R")