diff --git a/cmd/tailscale/cli/bugreport.go b/cmd/tailscale/cli/bugreport.go
index f22193131..5595b66b2 100644
--- a/cmd/tailscale/cli/bugreport.go
+++ b/cmd/tailscale/cli/bugreport.go
@@ -7,6 +7,7 @@
 import (
 	"context"
 	"errors"
+	"fmt"
 
 	"github.com/peterbourgon/ff/v3/ffcli"
 )
@@ -31,6 +32,6 @@ func runBugReport(ctx context.Context, args []string) error {
 	if err != nil {
 		return err
 	}
-	outln(logMarker)
+	fmt.Println(logMarker)
 	return nil
 }
diff --git a/cmd/tailscale/cli/cert.go b/cmd/tailscale/cli/cert.go
index e2a525bda..cb7a3a94f 100644
--- a/cmd/tailscale/cli/cert.go
+++ b/cmd/tailscale/cli/cert.go
@@ -27,7 +27,7 @@
 	ShortHelp:  "get TLS certs",
 	ShortUsage: "cert [flags] <domain>",
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("cert")
+		fs := flag.NewFlagSet("cert", flag.ExitOnError)
 		fs.StringVar(&certArgs.certFile, "cert-file", "", "output cert file or \"-\" for stdout; defaults to DOMAIN.crt if --cert-file and --key-file are both unset")
 		fs.StringVar(&certArgs.keyFile, "key-file", "", "output cert file or \"-\" for stdout; defaults to DOMAIN.key if --cert-file and --key-file are both unset")
 		fs.BoolVar(&certArgs.serve, "serve-demo", false, "if true, serve on port :443 using the cert as a demo, instead of writing out the files to disk")
@@ -79,7 +79,7 @@ func runCert(ctx context.Context, args []string) error {
 	domain := args[0]
 
 	printf := func(format string, a ...any) {
-		printf(format, a...)
+		fmt.Printf(format, a...)
 	}
 	if certArgs.certFile == "-" || certArgs.keyFile == "-" {
 		printf = log.Printf
@@ -138,7 +138,7 @@ func runCert(ctx context.Context, args []string) error {
 
 func writeIfChanged(filename string, contents []byte, mode os.FileMode) (changed bool, err error) {
 	if filename == "-" {
-		Stdout.Write(contents)
+		os.Stdout.Write(contents)
 		return false, nil
 	}
 	if old, err := os.ReadFile(filename); err == nil && bytes.Equal(contents, old) {
diff --git a/cmd/tailscale/cli/cli.go b/cmd/tailscale/cli/cli.go
index fa76ba33e..cfc320ff3 100644
--- a/cmd/tailscale/cli/cli.go
+++ b/cmd/tailscale/cli/cli.go
@@ -33,22 +33,6 @@
 	"tailscale.com/version/distro"
 )
 
-var Stderr io.Writer = os.Stderr
-var Stdout io.Writer = os.Stdout
-
-func printf(format string, a ...any) {
-	fmt.Fprintf(Stdout, format, a...)
-}
-
-// outln is like fmt.Println in the common case, except when Stdout is
-// changed (as in js/wasm).
-//
-// It's not named println because that looks like the Go built-in
-// which goes to stderr and formats slightly differently.
-func outln(a ...any) {
-	fmt.Fprintln(Stdout, a...)
-}
-
 // ActLikeCLI reports whether a GUI application should act like the
 // CLI based on os.Args, GOOS, the context the process is running in
 // (pty, parent PID), etc.
@@ -95,16 +79,6 @@ func ActLikeCLI() bool {
 	return false
 }
 
-func newFlagSet(name string) *flag.FlagSet {
-	onError := flag.ExitOnError
-	if runtime.GOOS == "js" {
-		onError = flag.ContinueOnError
-	}
-	fs := flag.NewFlagSet(name, onError)
-	fs.SetOutput(Stderr)
-	return fs
-}
-
 // CleanUpArgs rewrites command line arguments for simplicity and backwards compatibility.
 // In particular, it rewrites --authkey to --auth-key.
 func CleanUpArgs(args []string) []string {
@@ -138,11 +112,11 @@ func Run(args []string) (err error) {
 	var warnOnce sync.Once
 	tailscale.SetVersionMismatchHandler(func(clientVer, serverVer string) {
 		warnOnce.Do(func() {
-			fmt.Fprintf(Stderr, "Warning: client version %q != tailscaled server version %q\n", clientVer, serverVer)
+			fmt.Fprintf(os.Stderr, "Warning: client version %q != tailscaled server version %q\n", clientVer, serverVer)
 		})
 	})
 
-	rootfs := newFlagSet("tailscale")
+	rootfs := flag.NewFlagSet("tailscale", flag.ExitOnError)
 	rootfs.StringVar(&rootArgs.socket, "socket", paths.DefaultTailscaledSocket(), "path to tailscaled's unix socket")
 
 	rootCmd := &ffcli.Command{
diff --git a/cmd/tailscale/cli/configure-host.go b/cmd/tailscale/cli/configure-host.go
index b54fc83b8..14cb6824b 100644
--- a/cmd/tailscale/cli/configure-host.go
+++ b/cmd/tailscale/cli/configure-host.go
@@ -31,7 +31,7 @@
 See: https://tailscale.com/kb/1152/synology-outbound/
 `),
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("configure-host")
+		fs := flag.NewFlagSet("configure-host", flag.ExitOnError)
 		return fs
 	})(),
 }
diff --git a/cmd/tailscale/cli/debug.go b/cmd/tailscale/cli/debug.go
index 9ff05e496..ec98b63c0 100644
--- a/cmd/tailscale/cli/debug.go
+++ b/cmd/tailscale/cli/debug.go
@@ -40,7 +40,7 @@
 	Exec:     runDebug,
 	LongHelp: `"tailscale debug" contains misc debug facilities; it is not a stable interface.`,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("debug")
+		fs := flag.NewFlagSet("debug", flag.ExitOnError)
 		fs.StringVar(&debugArgs.file, "file", "", "get, delete:NAME, or NAME")
 		fs.StringVar(&debugArgs.cpuFile, "cpu-profile", "", "if non-empty, grab a CPU profile for --profile-sec seconds and write it to this file; - for stdout")
 		fs.StringVar(&debugArgs.memFile, "mem-profile", "", "if non-empty, grab a memory profile and write it to this file; - for stdout")
@@ -63,7 +63,7 @@
 			Exec:      runDaemonMetrics,
 			ShortHelp: "print tailscaled's metrics",
 			FlagSet: (func() *flag.FlagSet {
-				fs := newFlagSet("metrics")
+				fs := flag.NewFlagSet("metrics", flag.ExitOnError)
 				fs.BoolVar(&metricsArgs.watch, "watch", false, "print JSON dump of delta values")
 				return fs
 			})(),
@@ -103,7 +103,7 @@
 			Exec:      runPrefs,
 			ShortHelp: "print prefs",
 			FlagSet: (func() *flag.FlagSet {
-				fs := newFlagSet("prefs")
+				fs := flag.NewFlagSet("prefs", flag.ExitOnError)
 				fs.BoolVar(&prefsArgs.pretty, "pretty", false, "If true, pretty-print output")
 				return fs
 			})(),
@@ -113,7 +113,7 @@
 			Exec:      runWatchIPN,
 			ShortHelp: "subscribe to IPN message bus",
 			FlagSet: (func() *flag.FlagSet {
-				fs := newFlagSet("watch-ipn")
+				fs := flag.NewFlagSet("watch-ipn", flag.ExitOnError)
 				fs.BoolVar(&watchIPNArgs.netmap, "netmap", true, "include netmap in messages")
 				return fs
 			})(),
@@ -128,7 +128,7 @@
 			Exec:      runTS2021,
 			ShortHelp: "debug ts2021 protocol connectivity",
 			FlagSet: (func() *flag.FlagSet {
-				fs := newFlagSet("ts2021")
+				fs := flag.NewFlagSet("ts2021", flag.ExitOnError)
 				fs.StringVar(&ts2021Args.host, "host", "controlplane.tailscale.com", "hostname of control plane")
 				fs.IntVar(&ts2021Args.version, "version", int(tailcfg.CurrentCapabilityVersion), "protocol version")
 				return fs
@@ -146,7 +146,7 @@
 
 func writeProfile(dst string, v []byte) error {
 	if dst == "-" {
-		_, err := Stdout.Write(v)
+		_, err := os.Stdout.Write(v)
 		return err
 	}
 	return os.WriteFile(dst, v, 0600)
@@ -198,7 +198,7 @@ func runDebug(ctx context.Context, args []string) error {
 			if err != nil {
 				fatalf("%v\n", err)
 			}
-			e := json.NewEncoder(Stdout)
+			e := json.NewEncoder(os.Stdout)
 			e.SetIndent("", "\t")
 			e.Encode(wfs)
 			return nil
@@ -212,7 +212,7 @@ func runDebug(ctx context.Context, args []string) error {
 			return err
 		}
 		log.Printf("Size: %v\n", size)
-		io.Copy(Stdout, rc)
+		io.Copy(os.Stdout, rc)
 		return nil
 	}
 	if usedFlag {
@@ -226,14 +226,14 @@ func runDebug(ctx context.Context, args []string) error {
 func runLocalCreds(ctx context.Context, args []string) error {
 	port, token, err := safesocket.LocalTCPPortAndToken()
 	if err == nil {
-		printf("curl -u:%s http://localhost:%d/localapi/v0/status\n", token, port)
+		fmt.Printf("curl -u:%s http://localhost:%d/localapi/v0/status\n", token, port)
 		return nil
 	}
 	if runtime.GOOS == "windows" {
-		printf("curl http://localhost:%v/localapi/v0/status\n", safesocket.WindowsLocalPort)
+		fmt.Printf("curl http://localhost:%v/localapi/v0/status\n", safesocket.WindowsLocalPort)
 		return nil
 	}
-	printf("curl --unix-socket %s http://foo/localapi/v0/status\n", paths.DefaultTailscaledSocket())
+	fmt.Printf("curl --unix-socket %s http://foo/localapi/v0/status\n", paths.DefaultTailscaledSocket())
 	return nil
 }
 
@@ -247,10 +247,10 @@ func runPrefs(ctx context.Context, args []string) error {
 		return err
 	}
 	if prefsArgs.pretty {
-		outln(prefs.Pretty())
+		fmt.Println(prefs.Pretty())
 	} else {
 		j, _ := json.MarshalIndent(prefs, "", "\t")
-		outln(string(j))
+		fmt.Println(string(j))
 	}
 	return nil
 }
@@ -268,7 +268,7 @@ func runWatchIPN(ctx context.Context, args []string) error {
 			n.NetMap = nil
 		}
 		j, _ := json.MarshalIndent(n, "", "\t")
-		printf("%s\n", j)
+		fmt.Printf("%s\n", j)
 	})
 	bc.RequestEngineStatus()
 	pump(ctx, bc, c)
@@ -282,7 +282,7 @@ func runDERPMap(ctx context.Context, args []string) error {
 			"failed to get local derp map, instead `curl %s/derpmap/default`: %w", ipn.DefaultControlURL, err,
 		)
 	}
-	enc := json.NewEncoder(Stdout)
+	enc := json.NewEncoder(os.Stdout)
 	enc.SetIndent("", "\t")
 	enc.Encode(dm)
 	return nil
@@ -299,7 +299,7 @@ func localAPIAction(action string) func(context.Context, []string) error {
 
 func runEnv(ctx context.Context, args []string) error {
 	for _, e := range os.Environ() {
-		outln(e)
+		fmt.Println(e)
 	}
 	return nil
 }
@@ -338,7 +338,7 @@ func runDaemonGoroutines(ctx context.Context, args []string) error {
 	if err != nil {
 		return err
 	}
-	Stdout.Write(goroutines)
+	os.Stdout.Write(goroutines)
 	return nil
 }
 
@@ -354,7 +354,7 @@ func runDaemonMetrics(ctx context.Context, args []string) error {
 			return err
 		}
 		if !metricsArgs.watch {
-			Stdout.Write(out)
+			os.Stdout.Write(out)
 			return nil
 		}
 		bs := bufio.NewScanner(bytes.NewReader(out))
@@ -391,9 +391,9 @@ type change struct {
 		if len(changes) > 0 {
 			format := fmt.Sprintf("%%-%ds %%+5d => %%v\n", maxNameLen)
 			for _, c := range changes {
-				fmt.Fprintf(Stdout, format, c.name, c.to-c.from, c.to)
+				fmt.Fprintf(os.Stdout, format, c.name, c.to-c.from, c.to)
 			}
-			io.WriteString(Stdout, "\n")
+			io.WriteString(os.Stdout, "\n")
 		}
 		time.Sleep(time.Second)
 	}
diff --git a/cmd/tailscale/cli/down.go b/cmd/tailscale/cli/down.go
index 9a139f315..34ed3765c 100644
--- a/cmd/tailscale/cli/down.go
+++ b/cmd/tailscale/cli/down.go
@@ -8,6 +8,7 @@
 	"context"
 	"flag"
 	"fmt"
+	"os"
 
 	"github.com/peterbourgon/ff/v3/ffcli"
 	"tailscale.com/ipn"
@@ -23,7 +24,7 @@
 }
 
 func newDownFlagSet() *flag.FlagSet {
-	downf := newFlagSet("down")
+	downf := flag.NewFlagSet("down", flag.ExitOnError)
 	registerAcceptRiskFlag(downf)
 	return downf
 }
@@ -44,7 +45,7 @@ func runDown(ctx context.Context, args []string) error {
 		return fmt.Errorf("error fetching current status: %w", err)
 	}
 	if st.BackendState == "Stopped" {
-		fmt.Fprintf(Stderr, "Tailscale was already stopped.\n")
+		fmt.Fprintf(os.Stderr, "Tailscale was already stopped.\n")
 		return nil
 	}
 	_, err = localClient.EditPrefs(ctx, &ipn.MaskedPrefs{
diff --git a/cmd/tailscale/cli/file.go b/cmd/tailscale/cli/file.go
index 4b29ddbc7..4d7cf7d54 100644
--- a/cmd/tailscale/cli/file.go
+++ b/cmd/tailscale/cli/file.go
@@ -54,7 +54,7 @@
 	ShortHelp:  "Copy file(s) to a host",
 	Exec:       runCp,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("cp")
+		fs := flag.NewFlagSet("cp", flag.ExitOnError)
 		fs.StringVar(&cpArgs.name, "name", "", "alternate filename to use, especially useful when <file> is \"-\" (stdin)")
 		fs.BoolVar(&cpArgs.verbose, "verbose", false, "verbose output")
 		fs.BoolVar(&cpArgs.targets, "targets", false, "list possible file cp targets")
@@ -100,7 +100,7 @@ func runCp(ctx context.Context, args []string) error {
 		return fmt.Errorf("can't send to %s: %v", target, err)
 	}
 	if isOffline {
-		fmt.Fprintf(Stderr, "# warning: %s is offline\n", target)
+		fmt.Fprintf(os.Stderr, "# warning: %s is offline\n", target)
 	}
 
 	if len(files) > 1 {
@@ -281,7 +281,7 @@ func runCpTargets(ctx context.Context, args []string) error {
 		if detail != "" {
 			detail = "\t" + detail
 		}
-		printf("%s\t%s%s\n", n.Addresses[0].Addr(), n.ComputedName, detail)
+		fmt.Printf("%s\t%s%s\n", n.Addresses[0].Addr(), n.ComputedName, detail)
 	}
 	return nil
 }
@@ -315,7 +315,7 @@ func (v *onConflict) Set(s string) error {
 	ShortHelp:  "Move files out of the Tailscale file inbox",
 	Exec:       runFileGet,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("get")
+		fs := flag.NewFlagSet("get", flag.ExitOnError)
 		fs.BoolVar(&getArgs.wait, "wait", false, "wait for a file to arrive if inbox is empty")
 		fs.BoolVar(&getArgs.loop, "loop", false, "run get in a loop, receiving files as they come in")
 		fs.BoolVar(&getArgs.verbose, "verbose", false, "verbose output")
@@ -415,7 +415,7 @@ func runFileGetOneBatch(ctx context.Context, dir string) []error {
 			break
 		}
 		if getArgs.verbose {
-			printf("waiting for file...")
+			fmt.Printf("waiting for file...")
 		}
 		if err := waitForFile(ctx); err != nil {
 			errs = append(errs, err)
@@ -436,7 +436,7 @@ func runFileGetOneBatch(ctx context.Context, dir string) []error {
 			continue
 		}
 		if getArgs.verbose {
-			printf("wrote %v as %v (%d bytes)\n", wf.Name, writtenFile, size)
+			fmt.Printf("wrote %v as %v (%d bytes)\n", wf.Name, writtenFile, size)
 		}
 		if err = localClient.DeleteWaitingFile(ctx, wf.Name); err != nil {
 			errs = append(errs, fmt.Errorf("deleting %q from inbox: %v", wf.Name, err))
@@ -448,7 +448,7 @@ func runFileGetOneBatch(ctx context.Context, dir string) []error {
 		// persistently stuck files are basically an error
 		errs = append(errs, fmt.Errorf("moved %d/%d files", deleted, len(wfs)))
 	} else if getArgs.verbose {
-		printf("moved %d/%d files\n", deleted, len(wfs))
+		fmt.Printf("moved %d/%d files\n", deleted, len(wfs))
 	}
 	return errs
 }
@@ -471,7 +471,7 @@ func runFileGet(ctx context.Context, args []string) error {
 		for {
 			errs := runFileGetOneBatch(ctx, dir)
 			for _, err := range errs {
-				outln(err)
+				fmt.Println(err)
 			}
 			if len(errs) > 0 {
 				// It's possible whatever caused the error(s) (e.g. conflicting target file,
@@ -493,7 +493,7 @@ func runFileGet(ctx context.Context, args []string) error {
 		return nil
 	}
 	for _, err := range errs[:len(errs)-1] {
-		outln(err)
+		fmt.Println(err)
 	}
 	return errs[len(errs)-1]
 }
diff --git a/cmd/tailscale/cli/ip.go b/cmd/tailscale/cli/ip.go
index 53790aaa4..91ff44914 100644
--- a/cmd/tailscale/cli/ip.go
+++ b/cmd/tailscale/cli/ip.go
@@ -22,7 +22,7 @@
 	LongHelp:   "Show Tailscale IP addresses for peer. Peer defaults to the current machine.",
 	Exec:       runIP,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("ip")
+		fs := flag.NewFlagSet("ip", flag.ExitOnError)
 		fs.BoolVar(&ipArgs.want1, "1", false, "only print one IP address")
 		fs.BoolVar(&ipArgs.want4, "4", false, "only print IPv4 address")
 		fs.BoolVar(&ipArgs.want6, "6", false, "only print IPv6 address")
@@ -85,7 +85,7 @@ func runIP(ctx context.Context, args []string) error {
 	for _, ip := range ips {
 		if ip.Is4() && v4 || ip.Is6() && v6 {
 			match = true
-			outln(ip)
+			fmt.Println(ip)
 		}
 	}
 	if !match {
diff --git a/cmd/tailscale/cli/nc.go b/cmd/tailscale/cli/nc.go
index 1f9edb185..b0a2490cd 100644
--- a/cmd/tailscale/cli/nc.go
+++ b/cmd/tailscale/cli/nc.go
@@ -29,7 +29,7 @@ func runNC(ctx context.Context, args []string) error {
 	}
 	description, ok := isRunningOrStarting(st)
 	if !ok {
-		printf("%s\n", description)
+		fmt.Printf("%s\n", description)
 		os.Exit(1)
 	}
 
diff --git a/cmd/tailscale/cli/netcheck.go b/cmd/tailscale/cli/netcheck.go
index a835b9189..549f25c47 100644
--- a/cmd/tailscale/cli/netcheck.go
+++ b/cmd/tailscale/cli/netcheck.go
@@ -13,6 +13,7 @@
 	"io/ioutil"
 	"log"
 	"net/http"
+	"os"
 	"sort"
 	"strings"
 	"time"
@@ -32,7 +33,7 @@
 	ShortHelp:  "Print an analysis of local network conditions",
 	Exec:       runNetcheck,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("netcheck")
+		fs := flag.NewFlagSet("netcheck", flag.ExitOnError)
 		fs.StringVar(&netcheckArgs.format, "format", "", `output format; empty (for human-readable), "json" or "json-line"`)
 		fs.DurationVar(&netcheckArgs.every, "every", 0, "if non-zero, do an incremental report with the given frequency")
 		fs.BoolVar(&netcheckArgs.verbose, "verbose", false, "verbose logs")
@@ -59,7 +60,7 @@ func runNetcheck(ctx context.Context, args []string) error {
 	}
 
 	if strings.HasPrefix(netcheckArgs.format, "json") {
-		fmt.Fprintln(Stderr, "# Warning: this JSON format is not yet considered a stable interface")
+		fmt.Fprintln(os.Stderr, "# Warning: this JSON format is not yet considered a stable interface")
 	}
 
 	dm, err := localClient.CurrentDERPMap(ctx)
@@ -111,38 +112,38 @@ func printReport(dm *tailcfg.DERPMap, report *netcheck.Report) error {
 	}
 	if j != nil {
 		j = append(j, '\n')
-		Stdout.Write(j)
+		os.Stdout.Write(j)
 		return nil
 	}
 
-	printf("\nReport:\n")
-	printf("\t* UDP: %v\n", report.UDP)
+	fmt.Printf("\nReport:\n")
+	fmt.Printf("\t* UDP: %v\n", report.UDP)
 	if report.GlobalV4 != "" {
-		printf("\t* IPv4: yes, %v\n", report.GlobalV4)
+		fmt.Printf("\t* IPv4: yes, %v\n", report.GlobalV4)
 	} else {
-		printf("\t* IPv4: (no addr found)\n")
+		fmt.Printf("\t* IPv4: (no addr found)\n")
 	}
 	if report.GlobalV6 != "" {
-		printf("\t* IPv6: yes, %v\n", report.GlobalV6)
+		fmt.Printf("\t* IPv6: yes, %v\n", report.GlobalV6)
 	} else if report.IPv6 {
-		printf("\t* IPv6: (no addr found)\n")
+		fmt.Printf("\t* IPv6: (no addr found)\n")
 	} else if report.OSHasIPv6 {
-		printf("\t* IPv6: no, but OS has support\n")
+		fmt.Printf("\t* IPv6: no, but OS has support\n")
 	} else {
-		printf("\t* IPv6: no, unavailable in OS\n")
+		fmt.Printf("\t* IPv6: no, unavailable in OS\n")
 	}
-	printf("\t* MappingVariesByDestIP: %v\n", report.MappingVariesByDestIP)
-	printf("\t* HairPinning: %v\n", report.HairPinning)
-	printf("\t* PortMapping: %v\n", portMapping(report))
+	fmt.Printf("\t* MappingVariesByDestIP: %v\n", report.MappingVariesByDestIP)
+	fmt.Printf("\t* HairPinning: %v\n", report.HairPinning)
+	fmt.Printf("\t* PortMapping: %v\n", portMapping(report))
 
 	// When DERP latency checking failed,
 	// magicsock will try to pick the DERP server that
 	// most of your other nodes are also using
 	if len(report.RegionLatency) == 0 {
-		printf("\t* Nearest DERP: unknown (no response to latency probes)\n")
+		fmt.Printf("\t* Nearest DERP: unknown (no response to latency probes)\n")
 	} else {
-		printf("\t* Nearest DERP: %v\n", dm.Regions[report.PreferredDERP].RegionName)
-		printf("\t* DERP latency:\n")
+		fmt.Printf("\t* Nearest DERP: %v\n", dm.Regions[report.PreferredDERP].RegionName)
+		fmt.Printf("\t* DERP latency:\n")
 		var rids []int
 		for rid := range dm.Regions {
 			rids = append(rids, rid)
@@ -169,7 +170,7 @@ func printReport(dm *tailcfg.DERPMap, report *netcheck.Report) error {
 			if netcheckArgs.verbose {
 				derpNum = fmt.Sprintf("derp%d, ", rid)
 			}
-			printf("\t\t- %3s: %-7s (%s%s)\n", r.RegionCode, latency, derpNum, r.RegionName)
+			fmt.Printf("\t\t- %3s: %-7s (%s%s)\n", r.RegionCode, latency, derpNum, r.RegionName)
 		}
 	}
 	return nil
diff --git a/cmd/tailscale/cli/ping.go b/cmd/tailscale/cli/ping.go
index de4970d89..60f949113 100644
--- a/cmd/tailscale/cli/ping.go
+++ b/cmd/tailscale/cli/ping.go
@@ -46,7 +46,7 @@
 `),
 	Exec: runPing,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("ping")
+		fs := flag.NewFlagSet("ping", flag.ExitOnError)
 		fs.BoolVar(&pingArgs.verbose, "verbose", false, "verbose output")
 		fs.BoolVar(&pingArgs.untilDirect, "until-direct", true, "stop once a direct path is established")
 		fs.BoolVar(&pingArgs.tsmp, "tsmp", false, "do a TSMP-level ping (through WireGuard, but not either host OS stack)")
@@ -88,7 +88,7 @@ func runPing(ctx context.Context, args []string) error {
 	}
 	description, ok := isRunningOrStarting(st)
 	if !ok {
-		printf("%s\n", description)
+		fmt.Printf("%s\n", description)
 		os.Exit(1)
 	}
 
@@ -103,7 +103,7 @@ func runPing(ctx context.Context, args []string) error {
 		return err
 	}
 	if self {
-		printf("%v is local Tailscale IP\n", ip)
+		fmt.Printf("%v is local Tailscale IP\n", ip)
 		return nil
 	}
 
@@ -120,7 +120,7 @@ func runPing(ctx context.Context, args []string) error {
 		cancel()
 		if err != nil {
 			if errors.Is(err, context.DeadlineExceeded) {
-				printf("ping %q timed out\n", ip)
+				fmt.Printf("ping %q timed out\n", ip)
 				if n == pingArgs.num {
 					if !anyPong {
 						return errors.New("no reply")
@@ -133,7 +133,7 @@ func runPing(ctx context.Context, args []string) error {
 		}
 		if pr.Err != "" {
 			if pr.IsLocalIP {
-				outln(pr.Err)
+				fmt.Println(pr.Err)
 				return nil
 			}
 			return errors.New(pr.Err)
@@ -149,7 +149,7 @@ func runPing(ctx context.Context, args []string) error {
 			via = string(pingType())
 		}
 		if pingArgs.peerAPI {
-			printf("hit peerapi of %s (%s) at %s in %s\n", pr.NodeIP, pr.NodeName, pr.PeerAPIURL, latency)
+			fmt.Printf("hit peerapi of %s (%s) at %s in %s\n", pr.NodeIP, pr.NodeName, pr.PeerAPIURL, latency)
 			return nil
 		}
 		anyPong = true
@@ -157,7 +157,7 @@ func runPing(ctx context.Context, args []string) error {
 		if pr.PeerAPIPort != 0 {
 			extra = fmt.Sprintf(", %d", pr.PeerAPIPort)
 		}
-		printf("pong from %s (%s%s) via %v in %v\n", pr.NodeName, pr.NodeIP, extra, via, latency)
+		fmt.Printf("pong from %s (%s%s) via %v in %v\n", pr.NodeName, pr.NodeIP, extra, via, latency)
 		if pingArgs.tsmp || pingArgs.icmp {
 			return nil
 		}
diff --git a/cmd/tailscale/cli/ssh_exec.go b/cmd/tailscale/cli/ssh_exec.go
index bee4d3242..c2153dc36 100644
--- a/cmd/tailscale/cli/ssh_exec.go
+++ b/cmd/tailscale/cli/ssh_exec.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !js && !windows
-// +build !js,!windows
+//go:build !windows
+// +build !windows
 
 package cli
 
diff --git a/cmd/tailscale/cli/ssh_exec_js.go b/cmd/tailscale/cli/ssh_exec_js.go
deleted file mode 100644
index 3dbbea6a2..000000000
--- a/cmd/tailscale/cli/ssh_exec_js.go
+++ /dev/null
@@ -1,17 +0,0 @@
-// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package cli
-
-import (
-	"errors"
-)
-
-func findSSH() (string, error) {
-	return "", errors.New("Not implemented")
-}
-
-func execSSH(ssh string, argv []string) error {
-	return errors.New("Not implemented")
-}
diff --git a/cmd/tailscale/cli/status.go b/cmd/tailscale/cli/status.go
index 830b2f000..5b65dbebc 100644
--- a/cmd/tailscale/cli/status.go
+++ b/cmd/tailscale/cli/status.go
@@ -46,7 +46,7 @@
 `),
 	Exec: runStatus,
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("status")
+		fs := flag.NewFlagSet("status", flag.ExitOnError)
 		fs.BoolVar(&statusArgs.json, "json", false, "output in JSON format (WARNING: format subject to change)")
 		fs.BoolVar(&statusArgs.web, "web", false, "run webserver with HTML showing status")
 		fs.BoolVar(&statusArgs.active, "active", false, "filter output to only peers with active sessions (not applicable to web mode)")
@@ -92,7 +92,7 @@ func runStatus(ctx context.Context, args []string) error {
 		if err != nil {
 			return err
 		}
-		printf("%s", j)
+		fmt.Printf("%s", j)
 		return nil
 	}
 	if statusArgs.web {
@@ -101,7 +101,7 @@ func runStatus(ctx context.Context, args []string) error {
 			return err
 		}
 		statusURL := interfaces.HTTPOfListener(ln)
-		printf("Serving Tailscale status at %v ...\n", statusURL)
+		fmt.Printf("Serving Tailscale status at %v ...\n", statusURL)
 		go func() {
 			<-ctx.Done()
 			ln.Close()
@@ -131,16 +131,16 @@ func runStatus(ctx context.Context, args []string) error {
 	// print health check information prior to checking LocalBackend state as
 	// it may provide an explanation to the user if we choose to exit early
 	if len(st.Health) > 0 {
-		printf("# Health check:\n")
+		fmt.Printf("# Health check:\n")
 		for _, m := range st.Health {
-			printf("#     - %s\n", m)
+			fmt.Printf("#     - %s\n", m)
 		}
-		outln()
+		fmt.Println()
 	}
 
 	description, ok := isRunningOrStarting(st)
 	if !ok {
-		outln(description)
+		fmt.Println(description)
 		os.Exit(1)
 	}
 
@@ -213,7 +213,7 @@ func runStatus(ctx context.Context, args []string) error {
 			printPS(ps)
 		}
 	}
-	Stdout.Write(buf.Bytes())
+	os.Stdout.Write(buf.Bytes())
 	return nil
 }
 
diff --git a/cmd/tailscale/cli/up.go b/cmd/tailscale/cli/up.go
index 36dcf4d86..31aac1b08 100644
--- a/cmd/tailscale/cli/up.go
+++ b/cmd/tailscale/cli/up.go
@@ -85,7 +85,7 @@ func acceptRouteDefault(goos string) bool {
 func inTest() bool { return flag.Lookup("test.v") != nil }
 
 func newUpFlagSet(goos string, upArgs *upArgsT) *flag.FlagSet {
-	upf := newFlagSet("up")
+	upf := flag.NewFlagSet("up", flag.ExitOnError)
 
 	upf.BoolVar(&upArgs.qr, "qr", false, "show QR code for login URLs")
 	upf.BoolVar(&upArgs.json, "json", false, "output in JSON format (WARNING: format subject to change)")
@@ -195,7 +195,7 @@ type upOutputJSON struct {
 }
 
 func warnf(format string, args ...any) {
-	printf("Warning: "+format+"\n", args...)
+	fmt.Printf("Warning: "+format+"\n", args...)
 }
 
 var (
@@ -538,7 +538,7 @@ func runUp(ctx context.Context, args []string) (retErr error) {
 				if env.upArgs.json {
 					printUpDoneJSON(ipn.NeedsMachineAuth, "")
 				} else {
-					fmt.Fprintf(Stderr, "\nTo authorize your machine, visit (as admin):\n\n\t%s\n\n", prefs.AdminPageURL())
+					fmt.Fprintf(os.Stderr, "\nTo authorize your machine, visit (as admin):\n\n\t%s\n\n", prefs.AdminPageURL())
 				}
 			case ipn.Running:
 				// Done full authentication process
@@ -546,7 +546,7 @@ func runUp(ctx context.Context, args []string) (retErr error) {
 					printUpDoneJSON(ipn.Running, "")
 				} else if printed {
 					// Only need to print an update if we printed the "please click" message earlier.
-					fmt.Fprintf(Stderr, "Success.\n")
+					fmt.Fprintf(os.Stderr, "Success.\n")
 				}
 				select {
 				case running <- true:
@@ -575,13 +575,13 @@ func runUp(ctx context.Context, args []string) (retErr error) {
 					fmt.Println(string(data))
 				}
 			} else {
-				fmt.Fprintf(Stderr, "\nTo authenticate, visit:\n\n\t%s\n\n", *url)
+				fmt.Fprintf(os.Stderr, "\nTo authenticate, visit:\n\n\t%s\n\n", *url)
 				if upArgs.qr {
 					q, err := qrcode.New(*url, qrcode.Medium)
 					if err != nil {
 						log.Printf("QR code error: %v", err)
 					} else {
-						fmt.Fprintf(Stderr, "%s\n", q.ToString(false))
+						fmt.Fprintf(os.Stderr, "%s\n", q.ToString(false))
 					}
 				}
 			}
@@ -695,12 +695,12 @@ func checkSSHUpWarnings(ctx context.Context) {
 		return
 	}
 	if len(st.Health) == 1 && strings.Contains(st.Health[0], "SSH") {
-		printf("%s\n", st.Health[0])
+		fmt.Printf("%s\n", st.Health[0])
 		return
 	}
-	printf("# Health check:\n")
+	fmt.Printf("# Health check:\n")
 	for _, m := range st.Health {
-		printf("    - %s\n", m)
+		fmt.Printf("    - %s\n", m)
 	}
 }
 
diff --git a/cmd/tailscale/cli/version.go b/cmd/tailscale/cli/version.go
index eca3f5148..99720b169 100644
--- a/cmd/tailscale/cli/version.go
+++ b/cmd/tailscale/cli/version.go
@@ -18,7 +18,7 @@
 	ShortUsage: "version [flags]",
 	ShortHelp:  "Print Tailscale version",
 	FlagSet: (func() *flag.FlagSet {
-		fs := newFlagSet("version")
+		fs := flag.NewFlagSet("version", flag.ExitOnError)
 		fs.BoolVar(&versionArgs.daemon, "daemon", false, "also print local node's daemon version")
 		return fs
 	})(),
@@ -34,16 +34,16 @@ func runVersion(ctx context.Context, args []string) error {
 		return fmt.Errorf("too many non-flag arguments: %q", args)
 	}
 	if !versionArgs.daemon {
-		outln(version.String())
+		fmt.Println(version.String())
 		return nil
 	}
 
-	printf("Client: %s\n", version.String())
+	fmt.Printf("Client: %s\n", version.String())
 
 	st, err := localClient.StatusWithoutPeers(ctx)
 	if err != nil {
 		return err
 	}
-	printf("Daemon: %s\n", st.Version)
+	fmt.Printf("Daemon: %s\n", st.Version)
 	return nil
 }
diff --git a/cmd/tailscale/cli/web.go b/cmd/tailscale/cli/web.go
index d53d1fda8..5702e8162 100644
--- a/cmd/tailscale/cli/web.go
+++ b/cmd/tailscale/cli/web.go
@@ -75,7 +75,7 @@ type tmplData struct {
 `),
 
 	FlagSet: (func() *flag.FlagSet {
-		webf := newFlagSet("web")
+		webf := flag.NewFlagSet("web", flag.ExitOnError)
 		webf.StringVar(&webArgs.listen, "listen", "localhost:8088", "listen address; use port 0 for automatic")
 		webf.BoolVar(&webArgs.cgi, "cgi", false, "run as CGI script")
 		return webf
diff --git a/cmd/tailscaled/tailscaled.go b/cmd/tailscaled/tailscaled.go
index 3ac8f8f2b..78a25321d 100644
--- a/cmd/tailscaled/tailscaled.go
+++ b/cmd/tailscaled/tailscaled.go
@@ -274,13 +274,6 @@ func ipnServerOpts() (o ipnserver.Options) {
 	}
 
 	switch goos {
-	case "js":
-		// The js/wasm client has no state storage so for now
-		// treat all interactive logins as ephemeral.
-		// TODO(bradfitz): if we start using browser LocalStorage
-		// or something, then rethink this.
-		o.LoginFlags = controlclient.LoginEphemeral
-		fallthrough
 	default:
 		o.SurviveDisconnects = true
 		o.AutostartStateKey = ipn.GlobalDaemonStateKey