diff --git a/Makefile b/Makefile
index 1fc275bd..b8db1d5e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,19 +1,15 @@
-NAME = ifconfig
+NAME=ifconfigd
 
-all: deps test build
-
-fmt:
-	gofmt -w=true *.go
+all: deps test install
 
 deps:
 	go get -d -v
 
-build:
-	@mkdir -p bin
-	go build -o bin/$(NAME)
+fmt:
+	go fmt ./...
 
 test:
-	go test
+	go test ./...
 
-docker-image:
-	docker build -t martinp/ifconfig .
+install:
+	go install
diff --git a/api/api.go b/api/api.go
new file mode 100644
index 00000000..d522297d
--- /dev/null
+++ b/api/api.go
@@ -0,0 +1,212 @@
+package api
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"log"
+	"net"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"html/template"
+
+	"github.com/gorilla/mux"
+	geoip2 "github.com/oschwald/geoip2-golang"
+)
+
+const (
+	IP_HEADER      = "x-ifconfig-ip"
+	COUNTRY_HEADER = "x-ifconfig-country"
+)
+
+var cliUserAgentExp = regexp.MustCompile("^(?i)(curl|wget|fetch\\slibfetch)\\/.*$")
+
+type API struct {
+	db       *geoip2.Reader
+	CORS     bool
+	Template string
+}
+
+func New() *API { return &API{} }
+
+func NewWithGeoIP(filepath string) (*API, error) {
+	db, err := geoip2.Open(filepath)
+	if err != nil {
+		return nil, err
+	}
+	return &API{db: db}, nil
+}
+
+type Cmd struct {
+	Name string
+	Args string
+}
+
+func (c *Cmd) String() string {
+	return c.Name + " " + c.Args
+}
+
+func cmdFromQueryParams(values url.Values) Cmd {
+	cmd, exists := values["cmd"]
+	if !exists || len(cmd) == 0 {
+		return Cmd{Name: "curl"}
+	}
+	switch cmd[0] {
+	case "fetch":
+		return Cmd{Name: "fetch", Args: "-qo -"}
+	case "wget":
+		return Cmd{Name: "wget", Args: "-qO -"}
+	}
+	return Cmd{Name: "curl"}
+}
+
+func ipFromRequest(r *http.Request) (net.IP, error) {
+	var host string
+	realIP := r.Header.Get("X-Real-IP")
+	var err error
+	if realIP != "" {
+		host = realIP
+	} else {
+		host, _, err = net.SplitHostPort(r.RemoteAddr)
+		if err != nil {
+			return nil, err
+		}
+	}
+	ip := net.ParseIP(host)
+	if ip == nil {
+		return nil, fmt.Errorf("could not parse IP: %s", host)
+	}
+	return ip, nil
+}
+
+func headerKeyFromRequest(r *http.Request) string {
+	vars := mux.Vars(r)
+	key, ok := vars["key"]
+	if !ok {
+		return ""
+	}
+	return key
+}
+
+func (a *API) LookupCountry(ip net.IP) (string, error) {
+	if a.db == nil {
+		return "", nil
+	}
+	record, err := a.db.Country(ip)
+	if err != nil {
+		return "", err
+	}
+	if country, exists := record.Country.Names["en"]; exists {
+		return country, nil
+	}
+	if country, exists := record.RegisteredCountry.Names["en"]; exists {
+		return country, nil
+	}
+	return "", fmt.Errorf("could not determine country for IP: %s", ip)
+}
+
+func (a *API) defaultHandler(w http.ResponseWriter, r *http.Request) {
+	cmd := cmdFromQueryParams(r.URL.Query())
+	funcMap := template.FuncMap{"ToLower": strings.ToLower}
+	t, err := template.New(filepath.Base(a.Template)).Funcs(funcMap).ParseFiles(a.Template)
+	if err != nil {
+		log.Print(err)
+		return
+	}
+	b, err := json.MarshalIndent(r.Header, "", "  ")
+	if err != nil {
+		log.Print(err)
+		return
+	}
+
+	var data = struct {
+		IP     string
+		JSON   string
+		Header http.Header
+		Cmd
+	}{r.Header.Get(IP_HEADER), string(b), r.Header, cmd}
+
+	if err := t.Execute(w, &data); err != nil {
+		log.Print(err)
+	}
+}
+
+func (a *API) jsonHandler(w http.ResponseWriter, r *http.Request) {
+	key := headerKeyFromRequest(r)
+	if key == "" {
+		key = IP_HEADER
+	}
+	value := map[string]string{key: r.Header.Get(key)}
+	b, err := json.MarshalIndent(value, "", "  ")
+	if err != nil {
+		log.Print(err)
+		return
+	}
+	w.Write(b)
+}
+
+func (a *API) cliHandler(w http.ResponseWriter, r *http.Request) {
+	key := headerKeyFromRequest(r)
+	if key == "" {
+		key = IP_HEADER
+	}
+	value := r.Header.Get(key)
+	if !strings.HasSuffix(value, "\n") {
+		value += "\n"
+	}
+	io.WriteString(w, value)
+}
+
+func cliMatcher(r *http.Request, rm *mux.RouteMatch) bool {
+	return cliUserAgentExp.MatchString(r.UserAgent())
+}
+
+func (a *API) requestFilter(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		ip, err := ipFromRequest(r)
+		if err != nil {
+			r.Header.Set(IP_HEADER, err.Error())
+		} else {
+			r.Header.Set(IP_HEADER, ip.String())
+			country, err := a.LookupCountry(ip)
+			if err != nil {
+				r.Header.Set(COUNTRY_HEADER, err.Error())
+			} else {
+				r.Header.Set(COUNTRY_HEADER, country)
+			}
+		}
+		if a.CORS {
+			w.Header().Set("Access-Control-Allow-Methods", "GET")
+			w.Header().Set("Access-Control-Allow-Origin", "*")
+		}
+		next.ServeHTTP(w, r)
+	})
+}
+
+func (a *API) Handlers() http.Handler {
+	r := mux.NewRouter()
+
+	// JSON
+	r.HandleFunc("/", a.jsonHandler).Methods("GET").Headers("Accept", "application/json")
+	r.HandleFunc("/{key}", a.jsonHandler).Methods("GET").Headers("Accept", "application/json")
+	r.HandleFunc("/{key}.json", a.jsonHandler).Methods("GET")
+
+	// CLI
+	r.HandleFunc("/", a.cliHandler).Methods("GET").MatcherFunc(cliMatcher)
+	r.HandleFunc("/{key}", a.cliHandler).Methods("GET").MatcherFunc(cliMatcher)
+
+	// Default
+	r.HandleFunc("/", a.defaultHandler).Methods("GET")
+
+	// Pass all requests through the request filter
+	return a.requestFilter(r)
+}
+
+func (a *API) ListenAndServe(addr string) error {
+	http.Handle("/", a.Handlers())
+	return http.ListenAndServe(addr, nil)
+}
diff --git a/api/api_test.go b/api/api_test.go
new file mode 100644
index 00000000..01fe0e2c
--- /dev/null
+++ b/api/api_test.go
@@ -0,0 +1,120 @@
+package api
+
+import (
+	"fmt"
+	"io/ioutil"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"reflect"
+	"testing"
+)
+
+func httpGet(url string, json bool, userAgent string) (string, error) {
+	r, err := http.NewRequest("GET", url, nil)
+	if err != nil {
+		return "", err
+	}
+	if json {
+		r.Header.Set("Accept", "application/json")
+	}
+	r.Header.Set("User-Agent", userAgent)
+	res, err := http.DefaultClient.Do(r)
+	if err != nil {
+		return "", err
+	}
+	defer res.Body.Close()
+	data, err := ioutil.ReadAll(res.Body)
+	if err != nil {
+		return "", err
+	}
+	return string(data), nil
+}
+
+func TestGetIP(t *testing.T) {
+	toJSON := func(k string, v string) string {
+		return fmt.Sprintf("{\n  \"%s\": \"%s\"\n}", k, v)
+	}
+	s := httptest.NewServer(New().Handlers())
+	var tests = []struct {
+		url       string
+		json      bool
+		out       string
+		userAgent string
+	}{
+		{s.URL, false, "127.0.0.1\n", "curl/7.26.0"},
+		{s.URL, false, "127.0.0.1\n", "Wget/1.13.4 (linux-gnu)"},
+		{s.URL, false, "127.0.0.1\n", "fetch libfetch/2.0"},
+		{s.URL + "/x-ifconfig-ip.json", false, toJSON("x-ifconfig-ip", "127.0.0.1"), ""},
+		{s.URL, true, toJSON("x-ifconfig-ip", "127.0.0.1"), ""},
+	}
+	for _, tt := range tests {
+		out, err := httpGet(tt.url, tt.json, tt.userAgent)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if out != tt.out {
+			t.Errorf("Expected %q, got %q", tt.out, out)
+		}
+	}
+}
+
+func TestIPFromRequest(t *testing.T) {
+	var tests = []struct {
+		in  *http.Request
+		out net.IP
+	}{
+		{&http.Request{RemoteAddr: "1.3.3.7:9999"}, net.ParseIP("1.3.3.7")},
+		{&http.Request{Header: http.Header{"X-Real-Ip": []string{"1.3.3.7"}}}, net.ParseIP("1.3.3.7")},
+	}
+	for _, tt := range tests {
+		ip, err := ipFromRequest(tt.in)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if !ip.Equal(tt.out) {
+			t.Errorf("Expected %s, got %s", tt.out, ip)
+		}
+	}
+}
+
+func TestCmdFromParameters(t *testing.T) {
+	var tests = []struct {
+		in  url.Values
+		out Cmd
+	}{
+		{url.Values{}, Cmd{Name: "curl"}},
+		{url.Values{"cmd": []string{"foo"}}, Cmd{Name: "curl"}},
+		{url.Values{"cmd": []string{"curl"}}, Cmd{Name: "curl"}},
+		{url.Values{"cmd": []string{"fetch"}}, Cmd{Name: "fetch", Args: "-qo -"}},
+		{url.Values{"cmd": []string{"wget"}}, Cmd{Name: "wget", Args: "-qO -"}},
+	}
+	for _, tt := range tests {
+		cmd := cmdFromQueryParams(tt.in)
+		if !reflect.DeepEqual(cmd, tt.out) {
+			t.Errorf("Expected %+v, got %+v", tt.out, cmd)
+		}
+	}
+}
+
+func TestCLIMatcher(t *testing.T) {
+	browserUserAgent := "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) " +
+		"AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.28 " +
+		"Safari/537.36"
+	var tests = []struct {
+		in  string
+		out bool
+	}{
+		{"curl/7.26.0", true},
+		{"Wget/1.13.4 (linux-gnu)", true},
+		{"fetch libfetch/2.0", true},
+		{browserUserAgent, false},
+	}
+	for _, tt := range tests {
+		r := &http.Request{Header: http.Header{"User-Agent": []string{tt.in}}}
+		if got := cliMatcher(r, nil); got != tt.out {
+			t.Errorf("Expected %t, got %t for %q", tt.out, got, tt.in)
+		}
+	}
+}
diff --git a/ifconfig.go b/ifconfig.go
deleted file mode 100644
index ae97ac7b..00000000
--- a/ifconfig.go
+++ /dev/null
@@ -1,202 +0,0 @@
-package main
-
-import (
-	"encoding/json"
-	"fmt"
-	"github.com/jessevdk/go-flags"
-	"github.com/oschwald/geoip2-golang"
-	"html/template"
-	"io"
-	"log"
-	"net"
-	"net/http"
-	"net/url"
-	"os"
-	"regexp"
-	"strings"
-)
-
-var agentExp = regexp.MustCompile("^(?i)(curl|wget|fetch\\slibfetch)\\/.*$")
-
-type Client struct {
-	IP     net.IP
-	JSON   string
-	Header http.Header
-	Cmd
-}
-
-type Cmd struct {
-	Name string
-	Args string
-}
-
-type Ifconfig struct {
-	DB *geoip2.Reader
-}
-
-func (c *Cmd) String() string {
-	return c.Name + " " + c.Args
-}
-
-func isCLI(userAgent string) bool {
-	return agentExp.MatchString(userAgent)
-}
-
-func parseRealIP(req *http.Request) net.IP {
-	var host string
-	realIP := req.Header.Get("X-Real-IP")
-	if realIP != "" {
-		host = realIP
-	} else {
-		host, _, _ = net.SplitHostPort(req.RemoteAddr)
-	}
-	return net.ParseIP(host)
-}
-
-func pathToKey(path string) string {
-	trimmed := strings.TrimSuffix(strings.TrimPrefix(path, "/"), ".json")
-	return strings.ToLower(trimmed)
-}
-
-func isJSON(req *http.Request) bool {
-	return strings.HasSuffix(req.URL.Path, ".json") ||
-		strings.Contains(req.Header.Get("Accept"), "application/json")
-}
-
-func (i *Ifconfig) LookupCountry(ip net.IP) (string, error) {
-	if i.DB == nil {
-		return "", nil
-	}
-	record, err := i.DB.Country(ip)
-	if err != nil {
-		return "", err
-	}
-	country, exists := record.Country.Names["en"]
-	if !exists {
-		country, exists = record.RegisteredCountry.Names["en"]
-		if !exists {
-			return "", fmt.Errorf(
-				"could not determine country for IP: %s", ip)
-		}
-	}
-	return country, nil
-}
-
-func (i *Ifconfig) JSON(req *http.Request, key string) (string, error) {
-	var header http.Header
-	if key == "all" {
-		header = req.Header
-	} else {
-		header = http.Header{
-			key: []string{req.Header.Get(key)},
-		}
-	}
-	b, err := json.MarshalIndent(header, "", "  ")
-	if err != nil {
-		return "", err
-	}
-	return string(b), nil
-}
-
-func (i *Ifconfig) Plain(req *http.Request, key string, ip net.IP) string {
-	if key == "" || key == "ip" {
-		return fmt.Sprintf("%s\n", ip)
-	}
-	return fmt.Sprintf("%s\n", req.Header.Get(key))
-}
-
-func lookupCmd(values url.Values) Cmd {
-	cmd, exists := values["cmd"]
-	if !exists || len(cmd) == 0 {
-		return Cmd{Name: "curl"}
-	}
-	switch cmd[0] {
-	case "curl":
-		return Cmd{Name: "curl"}
-	case "fetch":
-		return Cmd{Name: "fetch", Args: "-qo -"}
-	case "wget":
-		return Cmd{Name: "wget", Args: "-qO -"}
-	}
-	return Cmd{Name: "curl"}
-}
-
-func (i *Ifconfig) handler(w http.ResponseWriter, req *http.Request) {
-	if req.Method != "GET" {
-		http.Error(w, "Invalid request method", 405)
-		return
-	}
-	ip := parseRealIP(req)
-	key := pathToKey(req.URL.Path)
-	cmd := lookupCmd(req.URL.Query())
-	country, err := i.LookupCountry(ip)
-	if err != nil {
-		log.Print(err)
-	}
-	req.Header["X-Ip-Country"] = []string{country}
-	if isJSON(req) {
-		out, err := i.JSON(req, key)
-		if err != nil {
-			log.Print(err)
-			http.Error(w, "Failed to marshal JSON", 500)
-			return
-		}
-		io.WriteString(w, out)
-	} else if isCLI(req.UserAgent()) {
-		io.WriteString(w, i.Plain(req, key, ip))
-	} else {
-		funcMap := template.FuncMap{
-			"ToLower": strings.ToLower,
-		}
-		t, _ := template.
-			New("index.html").
-			Funcs(funcMap).
-			ParseFiles("index.html")
-		b, err := json.MarshalIndent(req.Header, "", "  ")
-		if err != nil {
-			log.Print(err)
-			http.Error(w, "Failed to marshal JSON", 500)
-			return
-		}
-		client := &Client{
-			IP:     ip,
-			JSON:   string(b),
-			Header: req.Header,
-			Cmd:    cmd,
-		}
-		t.Execute(w, client)
-	}
-}
-
-func Create(path string) (*Ifconfig, error) {
-	if path == "" {
-		log.Print("Path to GeoIP database not given. Country lookup will be disabled")
-		return &Ifconfig{}, nil
-	}
-	db, err := geoip2.Open(path)
-	if err != nil {
-		return nil, err
-	}
-	return &Ifconfig{DB: db}, nil
-}
-
-func main() {
-	var opts struct {
-		DBPath string `short:"f" long:"file" description:"Path to GeoIP database" value-name:"FILE" default:""`
-		Listen string `short:"l" long:"listen" description:"Listening address" value-name:"ADDR" default:":8080"`
-	}
-	_, err := flags.ParseArgs(&opts, os.Args)
-	if err != nil {
-		os.Exit(1)
-	}
-	i, err := Create(opts.DBPath)
-	if err != nil {
-		log.Fatal(err)
-	}
-
-	http.HandleFunc("/", i.handler)
-	log.Printf("Listening on %s", opts.Listen)
-	if err := http.ListenAndServe(opts.Listen, nil); err != nil {
-		log.Fatal("ListenAndServe: ", err)
-	}
-}
diff --git a/ifconfig_test.go b/ifconfig_test.go
deleted file mode 100644
index d730587c..00000000
--- a/ifconfig_test.go
+++ /dev/null
@@ -1,59 +0,0 @@
-package main
-
-import (
-	"net/url"
-	"testing"
-)
-
-func TestIsCLI(t *testing.T) {
-	userAgents := []string{"curl/7.26.0", "Wget/1.13.4 (linux-gnu)",
-		"fetch libfetch/2.0"}
-
-	for _, userAgent := range userAgents {
-		if !isCLI(userAgent) {
-			t.Errorf("Expected true for %s", userAgent)
-		}
-	}
-
-	browserUserAgent := "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_4) " +
-		"AppleWebKit/537.36 (KHTML, like Gecko) Chrome/30.0.1599.28 " +
-		"Safari/537.36"
-	if isCLI(browserUserAgent) {
-		t.Errorf("Expected false for %s", browserUserAgent)
-	}
-}
-
-func TestPathToKey(t *testing.T) {
-	if key := pathToKey("/ip"); key != "ip" {
-		t.Fatalf("Expected 'ip', got '%s'", key)
-	}
-	if key := pathToKey("/User-Agent"); key != "user-agent" {
-		t.Fatalf("Expected 'user-agent', got '%s'", key)
-	}
-	if key := pathToKey("/all.json"); key != "all" {
-		t.Fatalf("Expected 'all', got '%s'", key)
-	}
-}
-
-func TestLookupCmd(t *testing.T) {
-	values := url.Values{"cmd": []string{"curl"}}
-	if v := lookupCmd(values); v.Name != "curl" {
-		t.Fatalf("Expected 'curl', got '%s'", v)
-	}
-	values = url.Values{"cmd": []string{"foo"}}
-	if v := lookupCmd(values); v.Name != "curl" {
-		t.Fatalf("Expected 'curl', got '%s'", v)
-	}
-	values = url.Values{}
-	if v := lookupCmd(values); v.Name != "curl" {
-		t.Fatalf("Expected 'curl', got '%s'", v)
-	}
-	values = url.Values{"cmd": []string{"wget"}}
-	if v := lookupCmd(values); v.Name != "wget" {
-		t.Fatalf("Expected 'wget', got '%s'", v)
-	}
-	values = url.Values{"cmd": []string{"fetch"}}
-	if v := lookupCmd(values); v.Name != "fetch" {
-		t.Fatalf("Expected 'fetch', got '%s'", v)
-	}
-}
diff --git a/index.html b/index.html
index 729824ba..f39050f7 100644
--- a/index.html
+++ b/index.html
@@ -6,7 +6,7 @@
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <meta name="description" content="What is my IP address?">
     <link href="//fonts.googleapis.com/css?family=Oswald" rel="stylesheet">
-    <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/pure/0.5.0/pure-min.css">
+    <link rel="stylesheet" href="//cdnjs.cloudflare.com/ajax/libs/pure/0.6.0/pure-min.css">
     <style>
       body {
         font-family: "Oswald", sans-serif;
@@ -61,8 +61,6 @@ <h2>Your IP:</h2>
           </tr>
           {{end}}
           {{end}}
-          <td><code><span class="command">{{ .Cmd.String }}</span> ifconfig.co/all.json</code></td>
-          <td><pre class="response">{{ .JSON }}</pre></td>
         </tbody>
       </table>
     </div>
diff --git a/main.go b/main.go
new file mode 100644
index 00000000..27a6b27c
--- /dev/null
+++ b/main.go
@@ -0,0 +1,40 @@
+package main
+
+import (
+	flags "github.com/jessevdk/go-flags"
+
+	"log"
+	"os"
+
+	"github.com/martinp/ifconfigd/api"
+)
+
+func main() {
+	var opts struct {
+		DBPath   string `short:"f" long:"file" description:"Path to GeoIP database" value-name:"FILE" default:""`
+		Listen   string `short:"l" long:"listen" description:"Listening address" value-name:"ADDR" default:":8080"`
+		CORS     bool   `short:"x" long:"cors" description:"Allow requests from other domains" default:"false"`
+		Template string `short:"t" long:"template" description:"Path to template" default:"index.html"`
+	}
+	_, err := flags.ParseArgs(&opts, os.Args)
+	if err != nil {
+		os.Exit(1)
+	}
+
+	var a *api.API
+	if opts.DBPath == "" {
+		a = api.New()
+	} else {
+		a, err = api.NewWithGeoIP(opts.DBPath)
+		if err != nil {
+			log.Fatal(err)
+		}
+	}
+	a.CORS = opts.CORS
+	a.Template = opts.Template
+
+	log.Printf("Listening on %s", opts.Listen)
+	if err := a.ListenAndServe(opts.Listen); err != nil {
+		log.Fatal(err)
+	}
+}