progressbar

Zero dependency cross platform (just needs basic ANSI codes and Unicode font support, and ANSI codes can be disabled too if needed) golang concurrent safe progress bar for terminal/CLIs, with 8x the resolution of others (8 steps per character).

Shows a spinner and/or a progress bar with optional prefix and extra info.

Also provides reader/writer wrappers to automatically show progress of downloads/uploads or other io operations. As well as a Writer that can be used concurrently with the progress bar to show other output on screen.

Examples

Manually updating a progress bar and additional output

Manually handling a 2 lines output updates (1 misc line and the 1 line for the progress bar)

	pb := progressbar.NewBar()
	fmt.Print("Progress bar example\n\n") // 1 empty line before the progress bar, for the demo
	n := 1000
	for i := 0; i <= n; i++ {
		pb.ProgressBar(100. * float64(i) / float64(n))
		if i%63 == 0 {
			progressbar.MoveCursorUp(1)
			fmt.Printf("Just an extra demo print for %d\n", i)
		}
		time.Sleep(20 * time.Millisecond)
	}

Source: example/example.go (-moveup mode)

Concurrent safe screen writer example

	pb := progressbar.NewBarWithWriter(os.Stdout)
	w := pb.Writer()
	fmt.Fprintln(w, "Progress bar example")
	// demonstrate concurrency safety:
	go PrintStuff(w, *everyFlag)
	// exact number of 'pixels', just to demo every smooth step:
	n := pb.Width * 8
	for i := 0; i <= n; i++ {
		pb.ProgressBar(100. * float64(i) / float64(n))
		time.Sleep(*delayFlag)
	}

go run fortio.org/progressbar/example@latest -color

Produces

Or without color:

◅███████████████████████████▊            ▻ 69.4%

Source: example/example.go (default mode)

Automatic Reader or Writer progress bar

	reader := progressbar.NewAutoReader(progressbar.NewBar(), resp.Body, resp.ContentLength)
	_, err = io.Copy(os.Stdout, reader)
	reader.Close()

See it in action with a progress bar while downloading a URL:

go run fortio.org/progressbar/auto_example@latest https://go.dev/ > go_dev.html

Will show a progress bar for instance

$  go run ./auto_example https://go.dev/dl/go1.24.1.src.tar.gz > /dev/null
Fetching https://go.dev/dl/go1.24.1.src.tar.gz
⣾ █████████████████████▌                   53.7% 15.766 Mb out of 29.352 Mb, 293ms elapsed, 53.790 Mb/s, 253ms remaining

Source (now includes a multi bar separating R/W): auto_example/auto_example.go

Multiple Bars updating concurrently

	mbar := progressbar.NewMultiBar(
		os.Stdout,
		1, // 1 extra line between bars by default.
		"b1",
		"longest prefix",
		"short",
		"b4",
	)
	wg := sync.WaitGroup{}
	for i, bar := range mbar {
		wg.Add(1)
		// Update at random speed so bars move differently for a demo:
		delay := time.Duration(5+rand.IntN(40)) * time.Millisecond
		bar.WriteAbove(fmt.Sprintf("\t\t\tBar %d delay is %v", i+1, delay))
		go func(b *progressbar.State) {
			UpdateBar(b, delay)
			wg.Done()
		}(bar)
	}
	wg.Wait()
	progressbar.MultiBarEnd(mbar)

Complete source: multi_example/multi_example.go

Multicurl

You can see it in use in fortio/multicurl cli too.

See also

If you have more advanced needs for TUI including raw mode input or readline, you can also see/use/have a look at

github.com/fortio/terminal

And still use this for a progress bar part.