diff --git a/cmd/ooniprobe/internal/config/settings.go b/cmd/ooniprobe/internal/config/settings.go
index 4715eef..e0e9a8a 100644
--- a/cmd/ooniprobe/internal/config/settings.go
+++ b/cmd/ooniprobe/internal/config/settings.go
@@ -1,38 +1,5 @@
 package config
 
-var websiteCategories = []string{
-	"ALDR",
-	"ANON",
-	"COMM",
-	"COMT",
-	"CTRL",
-	"CULTR",
-	"DATE",
-	"ECON",
-	"ENV",
-	"FILE",
-	"GAME",
-	"GMB",
-	"GOVT",
-	"GRP",
-	"HACK",
-	"HATE",
-	"HOST",
-	"HUMR",
-	"IGO",
-	"LGBT",
-	"MILX",
-	"MMED",
-	"NEWS",
-	"POLR",
-	"PORN",
-	"PROV",
-	"PUBH",
-	"REL",
-	"SRCH",
-	"XED",
-}
-
 // Sharing settings
 type Sharing struct {
 	UploadResults bool `json:"upload_results"`
@@ -45,6 +12,7 @@ type Advanced struct {
 
 // Nettests related settings
 type Nettests struct {
+	WebsitesMaxRuntime           int64    `json:"websites_max_runtime"`
 	WebsitesURLLimit             int64    `json:"websites_url_limit"`
 	WebsitesEnabledCategoryCodes []string `json:"websites_enabled_category_codes"`
 }
diff --git a/cmd/ooniprobe/internal/config/testdata/valid-config.json b/cmd/ooniprobe/internal/config/testdata/valid-config.json
index f609bdf..a331c8b 100644
--- a/cmd/ooniprobe/internal/config/testdata/valid-config.json
+++ b/cmd/ooniprobe/internal/config/testdata/valid-config.json
@@ -5,7 +5,7 @@
     "upload_results": true
   },
   "nettests": {
-    "websites_url_limit": 0
+    "websites_max_runtime": 0
   },
   "advanced": {
     "send_crash_reports": true
diff --git a/cmd/ooniprobe/internal/nettests/nettests.go b/cmd/ooniprobe/internal/nettests/nettests.go
index 71ba5b0..14e788a 100644
--- a/cmd/ooniprobe/internal/nettests/nettests.go
+++ b/cmd/ooniprobe/internal/nettests/nettests.go
@@ -111,10 +111,16 @@ func (c *Controller) Run(builder *engine.ExperimentBuilder, inputs []string) err
 		}
 	}
 
-	c.ntStartTime = time.Now()
+	maxRuntime := time.Duration(c.Probe.Config().Nettests.WebsitesMaxRuntime) * time.Second
+	start := time.Now()
+	c.ntStartTime = start
 	for idx, input := range inputs {
-		if c.Probe.IsTerminated() == true {
-			log.Debug("isTerminated == true, breaking the input loop")
+		if c.Probe.IsTerminated() {
+			log.Info("user requested us to terminate using Ctrl-C")
+			break
+		}
+		if maxRuntime > 0 && time.Since(start) > maxRuntime {
+			log.Info("exceeded maximum runtime")
 			break
 		}
 		c.curInputIdx = idx // allow for precise progress
diff --git a/cmd/ooniprobe/internal/nettests/run.go b/cmd/ooniprobe/internal/nettests/run.go
index ca92692..216fd41 100644
--- a/cmd/ooniprobe/internal/nettests/run.go
+++ b/cmd/ooniprobe/internal/nettests/run.go
@@ -1,6 +1,8 @@
 package nettests
 
 import (
+	"time"
+
 	"github.com/apex/log"
 	"github.com/ooni/probe-cli/v3/cmd/ooniprobe/internal/database"
 	"github.com/ooni/probe-cli/v3/cmd/ooniprobe/internal/ooni"
@@ -15,9 +17,36 @@ type RunGroupConfig struct {
 	Inputs     []string
 }
 
+const websitesURLLimitRemoved = `WARNING: CONFIGURATION CHANGE REQUIRED:
+
+* Since ooniprobe 3.9.0, websites_url_limit has been replaced
+  by websites_max_runtime in the configuration
+
+* To silence this warning either set websites_url_limit to zero or
+  replace it with websites_max_runtime
+
+* For the rest of 2021, we will automatically convert websites_url_limit
+  to websites_max_runtime (if the latter is not already set)
+
+* We will consider that each URL in websites_url_limit takes five
+  seconds to run and thus calculate websites_max_runtime
+
+* Since 2022, we will start silently ignoring websites_url_limit
+`
+
 // RunGroup runs a group of nettests according to the specified config.
 func RunGroup(config RunGroupConfig) error {
-	if config.Probe.IsTerminated() == true {
+	if config.Probe.Config().Nettests.WebsitesURLLimit > 0 {
+		log.Warn(websitesURLLimitRemoved)
+		if config.Probe.Config().Nettests.WebsitesMaxRuntime <= 0 {
+			limit := config.Probe.Config().Nettests.WebsitesURLLimit
+			maxRuntime := 5 * limit
+			config.Probe.Config().Nettests.WebsitesMaxRuntime = maxRuntime
+		}
+		time.Sleep(30 * time.Second)
+	}
+
+	if config.Probe.IsTerminated() {
 		log.Debugf("context is terminated, stopping runNettestGroup early")
 		return nil
 	}
diff --git a/cmd/ooniprobe/internal/nettests/web_connectivity.go b/cmd/ooniprobe/internal/nettests/web_connectivity.go
index 3e15472..741572c 100644
--- a/cmd/ooniprobe/internal/nettests/web_connectivity.go
+++ b/cmd/ooniprobe/internal/nettests/web_connectivity.go
@@ -9,16 +9,10 @@ import (
 	"github.com/ooni/probe-cli/v3/internal/engine/model"
 )
 
-// TODO(bassosimone): we should remove the limit argument and
-// we should also remove it from the config.
-
 // TODO(bassosimone): we should propagate the kind of run
 // to here such that we get the right runType.
 
-// TODO(bassosimone): we are breaking the use case in which
-// someone choose the number of URLs explicitly via the config.
-
-func lookupURLs(ctl *Controller, limit int64, categories []string) ([]string, map[int64]int64, error) {
+func lookupURLs(ctl *Controller, categories []string) ([]string, map[int64]int64, error) {
 	inputloader := &engine.InputLoader{
 		CheckInConfig: &model.CheckInConfig{
 			WebConnectivity: model.CheckInConfigWebConnectivity{
@@ -53,13 +47,12 @@ func lookupURLs(ctl *Controller, limit int64, categories []string) ([]string, ma
 }
 
 // WebConnectivity test implementation
-type WebConnectivity struct {
-}
+type WebConnectivity struct{}
 
 // Run starts the test
 func (n WebConnectivity) Run(ctl *Controller) error {
 	log.Debugf("Enabled category codes are the following %v", ctl.Probe.Config().Nettests.WebsitesEnabledCategoryCodes)
-	urls, urlIDMap, err := lookupURLs(ctl, ctl.Probe.Config().Nettests.WebsitesURLLimit, ctl.Probe.Config().Nettests.WebsitesEnabledCategoryCodes)
+	urls, urlIDMap, err := lookupURLs(ctl, ctl.Probe.Config().Nettests.WebsitesEnabledCategoryCodes)
 	if err != nil {
 		return err
 	}
diff --git a/cmd/ooniprobe/internal/ooni/default-config.json b/cmd/ooniprobe/internal/ooni/default-config.json
index f609bdf..a331c8b 100644
--- a/cmd/ooniprobe/internal/ooni/default-config.json
+++ b/cmd/ooniprobe/internal/ooni/default-config.json
@@ -5,7 +5,7 @@
     "upload_results": true
   },
   "nettests": {
-    "websites_url_limit": 0
+    "websites_max_runtime": 0
   },
   "advanced": {
     "send_crash_reports": true
diff --git a/cmd/ooniprobe/testdata/testing-config.json b/cmd/ooniprobe/testdata/testing-config.json
index 993f3b4..8de393b 100644
--- a/cmd/ooniprobe/testdata/testing-config.json
+++ b/cmd/ooniprobe/testdata/testing-config.json
@@ -5,7 +5,7 @@
     "upload_results": true
   },
   "nettests": {
-    "websites_url_limit": 10
+    "websites_max_runtime": 15
   },
   "advanced": {
     "send_crash_reports": true
diff --git a/debian/ooniprobe.conf.disabled b/debian/ooniprobe.conf.disabled
index 7124af6..528b14f 100644
--- a/debian/ooniprobe.conf.disabled
+++ b/debian/ooniprobe.conf.disabled
@@ -6,7 +6,7 @@
     "upload_results": true
   },
   "nettests": {
-    "websites_url_limit": 0,
+    "websites_max_runtime": 0,
     "websites_enabled_category_codes": null
   },
   "advanced": {