diff --git a/http/errorpages/errorpages_test.go b/http/errorpages/errorpages_test.go
index 4ab90f8f..00a8dc15 100644
--- a/http/errorpages/errorpages_test.go
+++ b/http/errorpages/errorpages_test.go
@@ -2,14 +2,16 @@ package errorpages
 
 import (
 	"fmt"
+	"io"
 	"net/http"
 	"net/http/httptest"
 	"os"
 	"testing"
 
+	"github.com/tj/assert"
+
 	"github.com/apex/up"
 	"github.com/apex/up/config"
-	"github.com/tj/assert"
 )
 
 var server = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
@@ -24,6 +26,13 @@ var server = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if r.URL.Path == "/400/json" {
+		w.WriteHeader(400)
+		w.Header().Set("Content-Type", "application/json")
+		io.WriteString(w, `{ "error": "bad_request" }`)
+		return
+	}
+
 	if r.URL.Path == "/500" {
 		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 		return
@@ -36,9 +45,9 @@ var server = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 	fmt.Fprintf(w, "World")
 })
 
-func TestErrors_defaults(t *testing.T) {
-	os.Chdir("testdata")
-	defer os.Chdir("..")
+func TestErrors_templates(t *testing.T) {
+	os.Chdir("testdata/templates")
+	defer os.Chdir("../..")
 
 	c := &up.Config{Name: "app"}
 	assert.NoError(t, c.Default(), "default")
@@ -51,7 +60,7 @@ func TestErrors_dir(t *testing.T) {
 	c := &up.Config{
 		Name: "app",
 		ErrorPages: config.ErrorPages{
-			Dir: "testdata",
+			Dir: "testdata/templates",
 		},
 	}
 
@@ -61,22 +70,72 @@ func TestErrors_dir(t *testing.T) {
 	test(t, c)
 }
 
-func test(t *testing.T, c *up.Config) {
+func TestErrors_defaults(t *testing.T) {
+	os.Chdir("testdata/defaults")
+	defer os.Chdir("../..")
+
+	c := &up.Config{Name: "app"}
+	assert.NoError(t, c.Default(), "default")
+	assert.NoError(t, c.Validate(), "validate")
+
+	h, err := New(c, server)
+	assert.NoError(t, err, "init")
+
+	t.Run("200", nonError(h))
+	t.Run("accepts text/html", acceptsHTML(h))
+	t.Run("accepts text/*", acceptsText(h))
+	t.Run("does not accept html", doesNotAcceptHTML(h))
+}
+
+func TestErrors_disabled(t *testing.T) {
+	c := &up.Config{
+		Name: "app",
+		ErrorPages: config.ErrorPages{
+			Disable: true,
+		},
+	}
+
+	assert.NoError(t, c.Default(), "default")
+	assert.NoError(t, c.Validate(), "validate")
+
 	h, err := New(c, server)
 	assert.NoError(t, err, "init")
 
-	t.Run("200", func(t *testing.T) {
+	t.Run("200", nonError(h))
+
+	t.Run("error", func(t *testing.T) {
 		res := httptest.NewRecorder()
-		req := httptest.NewRequest("GET", "/", nil)
+		req := httptest.NewRequest("GET", "/404", nil)
 
 		h.ServeHTTP(res, req)
 
-		assert.Equal(t, 200, res.Code)
-		assert.Equal(t, "bar", res.Header().Get("X-Foo"))
-		assert.Equal(t, "text/plain", res.Header().Get("Content-Type"))
-		assert.Equal(t, "Hello World", res.Body.String())
+		assert.Equal(t, 404, res.Code)
+		assert.Equal(t, "text/plain; charset=utf-8", res.Header().Get("Content-Type"))
+		assert.Equal(t, "Not Found\n", res.Body.String())
 	})
 
+	t.Run("json error", func(t *testing.T) {
+		res := httptest.NewRecorder()
+		req := httptest.NewRequest("GET", "/400/json", nil)
+		req.Header.Set("Accept", "application/json")
+
+		h.ServeHTTP(res, req)
+
+		assert.Equal(t, 400, res.Code)
+		assert.Equal(t, "application/json", res.Header().Get("Content-Type"))
+		assert.Equal(t, `{ "error": "bad_request" }`, res.Body.String())
+	})
+}
+
+func test(t *testing.T, c *up.Config) {
+	h, err := New(c, server)
+	assert.NoError(t, err, "init")
+
+	t.Run("200", nonError(h))
+	t.Run("accepts text/html", acceptsHTML(h))
+	t.Run("accepts text/*", acceptsText(h))
+	t.Run("does not accept html", doesNotAcceptHTML(h))
+
 	t.Run("exact", func(t *testing.T) {
 		res := httptest.NewRecorder()
 		req := httptest.NewRequest("GET", "/404", nil)
@@ -101,8 +160,24 @@ func test(t *testing.T, c *up.Config) {
 		assert.Equal(t, "text/html; charset=utf-8", res.Header().Get("Content-Type"))
 		assert.Equal(t, "500 – Internal Server Error\n", res.Body.String())
 	})
+}
 
-	t.Run("default text/html", func(t *testing.T) {
+func nonError(h http.Handler) func(t *testing.T) {
+	return func(t *testing.T) {
+		res := httptest.NewRecorder()
+		req := httptest.NewRequest("GET", "/", nil)
+
+		h.ServeHTTP(res, req)
+
+		assert.Equal(t, 200, res.Code)
+		assert.Equal(t, "bar", res.Header().Get("X-Foo"))
+		assert.Equal(t, "text/plain", res.Header().Get("Content-Type"))
+		assert.Equal(t, "Hello World", res.Body.String())
+	}
+}
+
+func acceptsHTML(h http.Handler) func(t *testing.T) {
+	return func(t *testing.T) {
 		res := httptest.NewRecorder()
 		req := httptest.NewRequest("GET", "/400", nil)
 		req.Header.Set("Accept", "text/html")
@@ -116,9 +191,11 @@ func test(t *testing.T, c *up.Config) {
 		assert.Contains(t, res.Body.String(), "<title>Bad Request – 400</title>", "title")
 		assert.Contains(t, res.Body.String(), `<span class="status">Bad Request</span>`, "status text")
 		assert.Contains(t, res.Body.String(), `<span class="code">400</span>`, "status code")
-	})
+	}
+}
 
-	t.Run("default text/*", func(t *testing.T) {
+func acceptsText(h http.Handler) func(t *testing.T) {
+	return func(t *testing.T) {
 		res := httptest.NewRecorder()
 		req := httptest.NewRequest("GET", "/400", nil)
 		req.Header.Set("Accept", "text/*")
@@ -132,5 +209,19 @@ func test(t *testing.T, c *up.Config) {
 		assert.Contains(t, res.Body.String(), "<title>Bad Request – 400</title>", "title")
 		assert.Contains(t, res.Body.String(), `<span class="status">Bad Request</span>`, "status text")
 		assert.Contains(t, res.Body.String(), `<span class="code">400</span>`, "status code")
-	})
+	}
+}
+
+func doesNotAcceptHTML(h http.Handler) func(t *testing.T) {
+	return func(t *testing.T) {
+		res := httptest.NewRecorder()
+		req := httptest.NewRequest("GET", "/400/json", nil)
+		req.Header.Set("Accept", "application/json")
+
+		h.ServeHTTP(res, req)
+
+		assert.Equal(t, 400, res.Code)
+		assert.Equal(t, "application/json", res.Header().Get("Content-Type"))
+		assert.Equal(t, `{ "error": "bad_request" }`, res.Body.String())
+	}
 }
diff --git a/http/errorpages/testdata/index.html b/http/errorpages/testdata/defaults/index.html
similarity index 100%
rename from http/errorpages/testdata/index.html
rename to http/errorpages/testdata/defaults/index.html
diff --git a/http/errorpages/testdata/up.json b/http/errorpages/testdata/defaults/up.json
similarity index 100%
rename from http/errorpages/testdata/up.json
rename to http/errorpages/testdata/defaults/up.json
diff --git a/http/errorpages/testdata/404.html b/http/errorpages/testdata/templates/404.html
similarity index 100%
rename from http/errorpages/testdata/404.html
rename to http/errorpages/testdata/templates/404.html
diff --git a/http/errorpages/testdata/5xx.html b/http/errorpages/testdata/templates/5xx.html
similarity index 100%
rename from http/errorpages/testdata/5xx.html
rename to http/errorpages/testdata/templates/5xx.html
diff --git a/http/errorpages/testdata/templates/index.html b/http/errorpages/testdata/templates/index.html
new file mode 100644
index 00000000..a8d87315
--- /dev/null
+++ b/http/errorpages/testdata/templates/index.html
@@ -0,0 +1 @@
+Index HTML
diff --git a/http/errorpages/testdata/templates/up.json b/http/errorpages/testdata/templates/up.json
new file mode 100644
index 00000000..fd1f8f63
--- /dev/null
+++ b/http/errorpages/testdata/templates/up.json
@@ -0,0 +1,3 @@
+{
+  "name": "app"
+}