diff --git a/ipinfo/cmd_tool.go b/ipinfo/cmd_tool.go
index 8650ef32..f66ca6fb 100644
--- a/ipinfo/cmd_tool.go
+++ b/ipinfo/cmd_tool.go
@@ -25,6 +25,7 @@ var completionsTool = &complete.Command{
 		"ip2n":      completionsToolIP2n,
 		"n2ip":      completionsToolN2IP,
 		"n2ip6":     completionsToolN2IP6,
+		"prefix":    completionsToolPrefix,
 	},
 	Flags: map[string]complete.Predictor{
 		"-h":     predict.Nothing,
@@ -52,6 +53,7 @@ Commands:
   ip2n         converts an IPv4 or IPv6 address to its decimal representation.
   n2ip	       evaluates a mathematical expression and converts it to an IPv4 or IPv6.
   n2ip6	       evaluates a mathematical expression and converts it to an IPv6.
+  prefix       misc. prefix tools related to CIDRs.
 
 Options:
   --help, -h
@@ -108,6 +110,8 @@ func cmdTool() error {
 		err = cmdToolN2IP()
 	case cmd == "n2ip6":
 		err = cmdToolN2IP6()
+	case cmd == "prefix":
+		err = cmdToolPrefix()
 	default:
 		err = toolHelp()
 	}
diff --git a/ipinfo/cmd_tool_prefix.go b/ipinfo/cmd_tool_prefix.go
new file mode 100644
index 00000000..675a952d
--- /dev/null
+++ b/ipinfo/cmd_tool_prefix.go
@@ -0,0 +1,67 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/ipinfo/cli/lib/complete"
+	"github.com/ipinfo/cli/lib/complete/predict"
+	"github.com/spf13/pflag"
+)
+
+var completionsToolPrefix = &complete.Command{
+	Sub: map[string]*complete.Command{
+		"addr": completionsToolPrefixAddr,
+	},
+	Flags: map[string]complete.Predictor{
+		"-h":     predict.Nothing,
+		"--help": predict.Nothing,
+	},
+}
+
+func printHelpToolPrefix() {
+	fmt.Printf(
+		`Usage: %s tool prefix <cmd> [<opts>] [<args>]
+
+Commands:
+  addr  returns the base IP address of a prefix.
+
+Options:
+  --help, -h
+    show help.
+`, progBase)
+}
+
+func toolPrefixHelp() (err error) {
+	pflag.BoolVarP(&fHelp, "help", "h", false, "show help.")
+	pflag.Parse()
+
+	if fHelp {
+		printHelpToolPrefix()
+		return nil
+	}
+
+	printHelpToolPrefix()
+	return nil
+}
+
+func cmdToolPrefix() error {
+	var err error
+	cmd := ""
+	if len(os.Args) > 3 {
+		cmd = os.Args[3]
+	}
+
+	switch {
+	case cmd == "addr":
+		err = cmdToolPrefixAddr()
+	default:
+		err = toolPrefixHelp()
+	}
+
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "err: %v\n", err)
+	}
+
+	return nil
+}
diff --git a/ipinfo/cmd_tool_prefix_addr.go b/ipinfo/cmd_tool_prefix_addr.go
new file mode 100644
index 00000000..c980bbf0
--- /dev/null
+++ b/ipinfo/cmd_tool_prefix_addr.go
@@ -0,0 +1,49 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/ipinfo/cli/lib"
+	"github.com/ipinfo/cli/lib/complete"
+	"github.com/ipinfo/cli/lib/complete/predict"
+	"github.com/spf13/pflag"
+)
+
+var completionsToolPrefixAddr = &complete.Command{
+	Flags: map[string]complete.Predictor{
+		"-h":     predict.Nothing,
+		"--help": predict.Nothing,
+	},
+}
+
+func printHelpToolPrefixAddr() {
+	fmt.Printf(
+		`Usage: %s tool prefix addr <cidr>
+
+Description:
+  Returns the base IP address of a prefix.
+
+Examples:
+  # CIDR Valid Examples.
+  $ %[1]s tool prefix addr 192.168.0.0/16
+  $ %[1]s tool prefix addr 10.0.0.0/8
+  $ %[1]s tool prefix addr 2001:0db8:1234::/48
+  $ %[1]s tool prefix addr 2606:2800:220:1::/64
+
+  # CIDR Invalid Examples.
+  $ %[1]s tool prefix addr 192.168.0.0/40
+  $ %[1]s tool prefix addr 2001:0db8:1234::/129
+
+Options:
+  --help, -h
+    show help.
+`, progBase)
+}
+
+func cmdToolPrefixAddr() (err error) {
+	f := lib.CmdToolPrefixAddrFlags{}
+	f.Init()
+	pflag.Parse()
+
+	return lib.CmdToolPrefixAddr(f, pflag.Args()[3:], printHelpToolPrefixAddr)
+}
diff --git a/lib/cmd_tool_prefix_addr.go b/lib/cmd_tool_prefix_addr.go
new file mode 100644
index 00000000..8786961a
--- /dev/null
+++ b/lib/cmd_tool_prefix_addr.go
@@ -0,0 +1,41 @@
+package lib
+
+import (
+	"fmt"
+	"net/netip"
+
+	"github.com/spf13/pflag"
+)
+
+type CmdToolPrefixAddrFlags struct {
+	Help bool
+}
+
+func (f *CmdToolPrefixAddrFlags) Init() {
+	pflag.BoolVarP(
+		&f.Help,
+		"help", "h", false,
+		"show help.",
+	)
+}
+
+func CmdToolPrefixAddr(f CmdToolPrefixAddrFlags, args []string, printHelp func()) error {
+	if f.Help {
+		printHelp()
+		return nil
+	}
+
+	op := func(input string, inputType INPUT_TYPE) error {
+		switch inputType {
+		case INPUT_TYPE_CIDR:
+			prefix, err := netip.ParsePrefix(input)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("%s,%s\n", input, prefix.Addr())
+		}
+		return nil
+	}
+
+	return GetInputFrom(args, true, true, op)
+}