diff --git a/completions.go b/completions.go
new file mode 100644
index 0000000..0009e71
--- /dev/null
+++ b/completions.go
@@ -0,0 +1,124 @@
+package cmd
+
+import (
+	"io"
+	"os"
+
+	"go.fifitido.net/cmd/opt"
+)
+
+var outputFileOption = opt.String("output", "o", "", "The file to output the completions to")
+
+func CompletionsSubcommand() *Command {
+	cmd := New(
+		"completions",
+		WithShortDescription("Generate shell completions"),
+		WithLongDescription("Generate shell completions"),
+	)
+
+	registerBashCompletions(cmd)
+	registerFishCompletions(cmd)
+	registerPowerShellCompletions(cmd)
+	registerZsgCompletions(cmd)
+
+	return cmd
+}
+
+func getCompletionsOut() io.Writer {
+	outputFile := outputFileOption.Value()
+
+	if outputFile != "" {
+		var err error
+		out, err := os.OpenFile(outputFile, os.O_WRONLY|os.O_CREATE, 0644)
+		if err != nil {
+			panic(err)
+		}
+		return out
+	}
+
+	return os.Stdout
+}
+
+func registerBashCompletions(parent *Command) *Command {
+	return New(
+		"bash",
+		WithShortDescription("Generate bash completions"),
+		WithLongDescription("Generate bash completions"),
+		WithOptions(outputFileOption),
+		WithParent(parent),
+		WithRunFunc(func(args []string) {
+			out := getCompletionsOut()
+
+			if fc, ok := out.(io.Closer); ok {
+				defer fc.Close()
+			}
+
+			if err := WriteBashCompletions(out, parent.Root()); err != nil {
+				panic(err)
+			}
+		}),
+	)
+}
+
+func registerFishCompletions(parent *Command) *Command {
+	return New(
+		"fish",
+		WithShortDescription("Generate fish completions"),
+		WithLongDescription("Generate fish completions"),
+		WithOptions(outputFileOption),
+		WithParent(parent),
+		WithRunFunc(func(args []string) {
+			out := getCompletionsOut()
+
+			if fc, ok := out.(io.Closer); ok {
+				defer fc.Close()
+			}
+
+			if err := WriteFishCompletions(out, parent.Root()); err != nil {
+				panic(err)
+			}
+		}),
+	)
+}
+
+func registerPowerShellCompletions(parent *Command) *Command {
+	return New(
+		"powershell",
+		WithShortDescription("Generate powershell completions"),
+		WithLongDescription("Generate powershell completions"),
+		WithOptions(outputFileOption),
+		WithParent(parent),
+		WithRunFunc(func(args []string) {
+			out := getCompletionsOut()
+
+			if fc, ok := out.(io.Closer); ok {
+				defer fc.Close()
+			}
+
+			if err := WritePowerShellCompletions(out, parent.Root()); err != nil {
+				panic(err)
+			}
+		}),
+	)
+}
+
+func registerZsgCompletions(parent *Command) *Command {
+	return New(
+		"zsh",
+		WithShortDescription("Generate zsh completions"),
+		WithLongDescription("Generate zsh completions"),
+		WithOptions(outputFileOption),
+		WithParent(parent),
+		WithRunFunc(func(args []string) {
+			out := getCompletionsOut()
+
+			if fc, ok := out.(io.Closer); ok {
+				defer fc.Close()
+			}
+
+			if err := WriteZshCompletions(out, parent.Root()); err != nil {
+				panic(err)
+			}
+		}),
+	)
+}
diff --git a/completions_bash.go b/completions_bash.go
new file mode 100644
index 0000000..a790090
--- /dev/null
+++ b/completions_bash.go
@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"io"
+	"text/template"
+
+	"go.fifitido.net/cmd/opt"
+)
+
+func WriteBashCompletions(out io.Writer, rootCmd *Command) error {
+	return bashTpl.Execute(out, map[string]any{
+		"rootCmd":    rootCmd,
+		"globalOpts": opt.Globals(),
+	})
+}
+
+var bashTpl = template.Must(template.New("bash").Parse(`
+	
+`))
diff --git a/completions_fish.go b/completions_fish.go
new file mode 100644
index 0000000..e2cb825
--- /dev/null
+++ b/completions_fish.go
@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"io"
+	"text/template"
+
+	"go.fifitido.net/cmd/opt"
+)
+
+func WriteFishCompletions(out io.Writer, rootCmd *Command) error {
+	return fishTpl.Execute(out, map[string]any{
+		"rootCmd":    rootCmd,
+		"globalOpts": opt.Globals(),
+	})
+}
+
+var fishTpl = template.Must(template.New("fish").Parse(`
+
+`))
diff --git a/completions_powershell.go b/completions_powershell.go
new file mode 100644
index 0000000..a0f271a
--- /dev/null
+++ b/completions_powershell.go
@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"io"
+	"text/template"
+
+	"go.fifitido.net/cmd/opt"
+)
+
+func WritePowerShellCompletions(out io.Writer, rootCmd *Command) error {
+	return powerShellTpl.Execute(out, map[string]any{
+		"rootCmd":    rootCmd,
+		"globalOpts": opt.Globals(),
+	})
+}
+
+var powerShellTpl = template.Must(template.New("PowerShell").Parse(`
+	
+`))
diff --git a/completions_zsh.go b/completions_zsh.go
new file mode 100644
index 0000000..885ec41
--- /dev/null
+++ b/completions_zsh.go
@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"io"
+	"text/template"
+
+	"go.fifitido.net/cmd/opt"
+)
+
+func WriteZshCompletions(out io.Writer, rootCmd *Command) error {
+	return zshTpl.Execute(out, map[string]any{
+		"rootCmd":    rootCmd,
+		"globalOpts": opt.Globals(),
+	})
+}
+
+var zshTpl = template.Must(template.New("zsh").Parse(`
+	
+`))