diff --git a/cmd/autocompletion.go b/cmd/autocompletion.go
new file mode 100644
index 00000000..26862deb
--- /dev/null
+++ b/cmd/autocompletion.go
@@ -0,0 +1,242 @@
+package cmd
+
+import (
+	"bufio"
+	"bytes"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+func init() {
+	autocompleteCmd.AddCommand(bashAutocompleteCmd)
+	autocompleteCmd.AddCommand(zshAutocompleteCmd)
+
+	RootCmd.AddCommand(autocompleteCmd)
+}
+
+var autocompleteCmd = &cobra.Command{
+	Use:   "completion",
+	Short: "Output shell completion code for the given shell (bash or zsh)",
+	Long: `
+Output shell completion code for bash or zsh
+This command prints shell code which must be evaluated to provide interactive
+completion of aws-okta commands.
+
+Bash
+	$ source <(aws-okta completion bash)
+will load the aws-okta completion code for bash. Note that this depends on the
+bash-completion framework. It must be sourced before sourcing the aws-okta
+completion, e.g. on macOS:
+	$ brew install bash-completion
+	$ source $(brew --prefix)/etc/bash_completion
+	$ source <(aws-okta completion bash)
+	(or, if you want to preserve completion within new terminal sessions)
+	$ echo 'source <(aws-okta completion bash)' >> ~/.bashrc
+
+Zsh
+	$ source <(aws-okta completion zsh)
+	(or, if you want to preserve completion within new terminal sessions)
+	$ echo 'source <(aws-okta completion zsh)' >> ~/.zshrc`,
+}
+
+var bashAutocompleteCmd = &cobra.Command{
+	Use:   "bash",
+	Short: "Output shell completion code for bash",
+	Long: `
+Output shell completion code for bash.
+This command prints shell code which must be evaluated to provide interactive
+completion of aws-okta commands.
+	$ source <(aws-okta completion bash)
+will load the aws-okta completion code for bash. Note that this depends on the
+bash-completion framework. It must be sourced before sourcing the aws-okta
+completion, e.g. on macOS:
+	$ brew install bash-completion
+	$ source $(brew --prefix)/etc/bash_completion
+	$ source <(aws-okta completion bash)
+	(or, if you want to preserve completion within new terminal sessions)
+	$ echo 'source <(aws-okta completion bash)' >> ~/.bashrc`,
+	RunE: runCompletionBash,
+}
+
+var zshAutocompleteCmd = &cobra.Command{
+	Use:   "zsh",
+	Short: "Output shell completion code for zsh",
+	Long: `
+Output shell completion code for zsh.
+This command prints shell code which must be evaluated to provide interactive
+completion of aws-okta commands.
+	$ source <(aws-okta completion zsh)
+	(or, if you want to preserve completion within new terminal sessions)
+	$ echo 'source <(aws-okta completion zsh)' >> ~/.zshrc
+zsh completions are only supported in versions of zsh >= 5.2`,
+	RunE: runCompletionZsh,
+}
+
+func runCompletionBash(cmd *cobra.Command, args []string) error {
+	out := bufio.NewWriter(os.Stdout)
+	defer out.Flush()
+	return RootCmd.GenBashCompletion(out)
+}
+
+// Copyright 2016 The Kubernetes Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+func runCompletionZsh(cmd *cobra.Command, args []string) error {
+	out := bufio.NewWriter(os.Stdout)
+	defer out.Flush()
+	zshInitialization := `
+__aws-okta_bash_source() {
+	alias shopt=':'
+	alias _expand=_bash_expand
+	alias _complete=_bash_comp
+	emulate -L sh
+	setopt kshglob noshglob braceexpand
+	source "$@"
+}
+__aws-okta_type() {
+	# -t is not supported by zsh
+	if [ "$1" == "-t" ]; then
+		shift
+		# fake Bash 4 to disable "complete -o nospace". Instead
+		# "compopt +-o nospace" is used in the code to toggle trailing
+		# spaces. We don't support that, but leave trailing spaces on
+		# all the time
+		if [ "$1" = "__aws-okta_compopt" ]; then
+			echo builtin
+			return 0
+		fi
+	fi
+	type "$@"
+}
+__aws-okta_compgen() {
+	local completions w
+	completions=( $(compgen "$@") ) || return $?
+	# filter by given word as prefix
+	while [[ "$1" = -* && "$1" != -- ]]; do
+		shift
+		shift
+	done
+	if [[ "$1" == -- ]]; then
+		shift
+	fi
+	for w in "${completions[@]}"; do
+		if [[ "${w}" = "$1"* ]]; then
+			echo "${w}"
+		fi
+	done
+}
+__aws-okta_compopt() {
+	true # don't do anything. Not supported by bashcompinit in zsh
+}
+__aws-okta_declare() {
+	if [ "$1" == "-F" ]; then
+		whence -w "$@"
+	else
+		builtin declare "$@"
+	fi
+}
+__aws-okta_ltrim_colon_completions()
+{
+	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
+		# Remove colon-word prefix from COMPREPLY items
+		local colon_word=${1%${1##*:}}
+		local i=${#COMPREPLY[*]}
+		while [[ $((--i)) -ge 0 ]]; do
+			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
+		done
+	fi
+}
+__aws-okta_get_comp_words_by_ref() {
+	cur="${COMP_WORDS[COMP_CWORD]}"
+	prev="${COMP_WORDS[${COMP_CWORD}-1]}"
+	words=("${COMP_WORDS[@]}")
+	cword=("${COMP_CWORD[@]}")
+}
+__aws-okta_filedir() {
+	local RET OLD_IFS w qw
+	__debug "_filedir $@ cur=$cur"
+	if [[ "$1" = \~* ]]; then
+		# somehow does not work. Maybe, zsh does not call this at all
+		eval echo "$1"
+		return 0
+	fi
+	OLD_IFS="$IFS"
+	IFS=$'\n'
+	if [ "$1" = "-d" ]; then
+		shift
+		RET=( $(compgen -d) )
+	else
+		RET=( $(compgen -f) )
+	fi
+	IFS="$OLD_IFS"
+	IFS="," __debug "RET=${RET[@]} len=${#RET[@]}"
+	for w in ${RET[@]}; do
+		if [[ ! "${w}" = "${cur}"* ]]; then
+			continue
+		fi
+		if eval "[[ \"\${w}\" = *.$1 || -d \"\${w}\" ]]"; then
+			qw="$(__aws-okta_quote "${w}")"
+			if [ -d "${w}" ]; then
+				COMPREPLY+=("${qw}/")
+			else
+				COMPREPLY+=("${qw}")
+			fi
+		fi
+	done
+}
+__aws-okta_quote() {
+    if [[ $1 == \'* || $1 == \"* ]]; then
+        # Leave out first character
+        printf %q "${1:1}"
+    else
+    	printf %q "$1"
+    fi
+}
+autoload -U +X bashcompinit && bashcompinit
+# use word boundary patterns for BSD or GNU sed
+LWORD='[[:<:]]'
+RWORD='[[:>:]]'
+if sed --help 2>&1 | grep -q GNU; then
+	LWORD='\<'
+	RWORD='\>'
+fi
+__aws-okta_convert_bash_to_zsh() {
+	sed \
+	-e 's/declare -F/whence -w/' \
+	-e 's/local \([a-zA-Z0-9_]*\)=/local \1; \1=/' \
+	-e 's/flags+=("\(--.*\)=")/flags+=("\1"); two_word_flags+=("\1")/' \
+	-e 's/must_have_one_flag+=("\(--.*\)=")/must_have_one_flag+=("\1")/' \
+	-e "s/${LWORD}_filedir${RWORD}/__aws-okta_filedir/g" \
+	-e "s/${LWORD}_get_comp_words_by_ref${RWORD}/__aws-okta_get_comp_words_by_ref/g" \
+	-e "s/${LWORD}__ltrim_colon_completions${RWORD}/__aws-okta_ltrim_colon_completions/g" \
+	-e "s/${LWORD}compgen${RWORD}/__aws-okta_compgen/g" \
+	-e "s/${LWORD}compopt${RWORD}/__aws-okta_compopt/g" \
+	-e "s/${LWORD}declare${RWORD}/__aws-okta_declare/g" \
+	-e "s/\\\$(type${RWORD}/\$(__aws-okta_type/g" \
+	<<'BASH_COMPLETION_EOF'
+`
+	out.Write([]byte(zshInitialization))
+
+	buf := new(bytes.Buffer)
+	RootCmd.GenBashCompletion(buf)
+	out.Write(buf.Bytes())
+
+	zshTail := `
+BASH_COMPLETION_EOF
+}
+__aws-okta_bash_source <(__aws-okta_convert_bash_to_zsh)
+`
+	out.Write([]byte(zshTail))
+	return nil
+}
diff --git a/cmd/exec.go b/cmd/exec.go
index f3365180..447be560 100644
--- a/cmd/exec.go
+++ b/cmd/exec.go
@@ -2,6 +2,9 @@ package cmd
 
 import (
 	"fmt"
+
+	log "github.com/sirupsen/logrus"
+
 	"os"
 	"os/exec"
 	"os/signal"
@@ -20,12 +23,21 @@ var (
 	assumeRoleTTL time.Duration
 )
 
+func mustListProfiles() lib.Profiles {
+  profiles, err := listProfiles()
+  if err != nil {
+    log.Panicf("Failed to list profiles: %v", err)
+  }
+  return profiles
+}
+
 // execCmd represents the exec command
 var execCmd = &cobra.Command{
-	Use:    "exec <profile> -- <command>",
-	Short:  "exec will run the command specified with aws credentials set in the environment",
-	RunE:   execRun,
-	PreRun: execPre,
+	Use:       "exec <profile> -- <command>",
+	Short:     "exec will run the command specified with aws credentials set in the environment",
+	RunE:      execRun,
+	PreRun:    execPre,
+	ValidArgs: listProfileNames(mustListProfiles()),
 }
 
 func init() {
diff --git a/cmd/list.go b/cmd/list.go
index e057d415..2bc53670 100644
--- a/cmd/list.go
+++ b/cmd/list.go
@@ -22,17 +22,21 @@ func init() {
 	RootCmd.AddCommand(listCmd)
 }
 
-func listRun(cmd *cobra.Command, args []string) error {
+func listProfiles() (lib.Profiles, error) {
 	config, err := lib.NewConfigFromEnv()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
 	profiles, err := config.Parse()
 	if err != nil {
-		return err
+		return nil, err
 	}
 
+	return profiles, nil
+}
+
+func listProfileNames(profiles lib.Profiles) []string {
 	// Let's sort this list of profiles so we can have some more deterministic output:
 	var profileNames []string
 
@@ -42,6 +46,17 @@ func listRun(cmd *cobra.Command, args []string) error {
 
 	sort.Strings(profileNames)
 
+	return profileNames
+}
+
+func listRun(cmd *cobra.Command, args []string) error {
+	profiles, err := listProfiles()
+	if err != nil {
+		return err
+	}
+
+	profileNames := listProfileNames(profiles)
+
 	w := new(tabwriter.Writer)
 	w.Init(os.Stdout, 0, 8, 2, '\t', 0)
 	fmt.Fprintln(w, "PROFILE\tARN\tSOURCE_ROLE\t")