diff --git a/doc.go b/doc.go
new file mode 100644
index 0000000..01e48b4
--- /dev/null
+++ b/doc.go
@@ -0,0 +1,21 @@
+/*
+This package is WIP. Please use/test/try and report issues, but be careful with production. OK?
+
+Pkger is powered by the dark magic of Go Modules, so they're like, totally required.
+
+With Go Modules pkger can resolve packages with accuracy. No more guessing and trying to
+figure out build paths, GOPATHS, etc... for this tired old lad.
+
+With the module's path correctly resolved, it can serve as the "root" directory for that
+module, and all files in that module's directory are available.
+
+		Paths:
+		* Paths should use UNIX style paths:
+			/cmd/pkger/main.go
+		* If unspecified the path's package is assumed to be the current module.
+		* Packages can specified in at the beginning of a path with a `:` seperator.
+			github.com/markbates/pkger:/cmd/pkger/main.go
+
+		"github.com/gobuffalo/buffalo:/go.mod" => $GOPATH/pkg/mod/github.com/gobuffalo/buffalo@v0.14.7/go.mod
+*/
+package pkger
diff --git a/file.go b/file.go
index 382dd54..8f6b7d1 100644
--- a/file.go
+++ b/file.go
@@ -21,9 +21,74 @@ type File struct {
 	path   Path
 	data   []byte
 	index  *index
+	writer io.ReadWriter
 	Source io.ReadCloser
 }
 
+func (f *File) Close() error {
+	defer func() {
+		f.Source = nil
+		f.writer = nil
+	}()
+	if f.Source != nil {
+		if c, ok := f.Source.(io.Closer); ok {
+			if err := c.Close(); err != nil {
+				return err
+			}
+		}
+	}
+
+	if f.writer == nil {
+		return nil
+	}
+
+	b, err := ioutil.ReadAll(f.writer)
+	if err != nil {
+		return err
+	}
+	f.data = b
+
+	fi := f.info
+	fi.size = int64(len(f.data))
+	fi.modTime = time.Now()
+	f.info = fi
+	return nil
+}
+
+func (f *File) Read(p []byte) (int, error) {
+	if len(f.data) > 0 && len(f.data) <= len(p) {
+		return copy(p, f.data), io.EOF
+	}
+
+	if len(f.data) > 0 {
+		f.Source = ioutil.NopCloser(bytes.NewReader(f.data))
+	}
+
+	if f.Source != nil {
+		return f.Source.Read(p)
+	}
+
+	of, err := f.her.Open(f.Path())
+	if err != nil {
+		return 0, err
+	}
+	f.Source = of
+	return f.Source.Read(p)
+}
+
+func (f *File) Write(b []byte) (int, error) {
+	if f.writer == nil {
+		f.writer = &bytes.Buffer{}
+	}
+	i, err := f.writer.Write(b)
+	fmt.Println(f.Name(), i, err)
+	return i, err
+}
+
+func (f File) HereInfo() here.Info {
+	return f.her
+}
+
 func (f File) MarshalJSON() ([]byte, error) {
 	m := map[string]interface{}{}
 	m["info"] = f.info
@@ -76,9 +141,7 @@ func (f *File) UnmarshalJSON(b []byte) error {
 	if !ok {
 		return fmt.Errorf("missing index")
 	}
-	f.index = &index{
-		Files: map[Path]*File{},
-	}
+	f.index = newIndex()
 	if err := json.Unmarshal(ind, f.index); err != nil {
 		return err
 	}
@@ -87,9 +150,7 @@ func (f *File) UnmarshalJSON(b []byte) error {
 
 func (f *File) Open(name string) (http.File, error) {
 	if f.index == nil {
-		f.index = &index{
-			Files: map[Path]*File{},
-		}
+		f.index = newIndex()
 	}
 	pt, err := Parse(name)
 	if err != nil {
@@ -148,16 +209,6 @@ func (f File) Stat() (os.FileInfo, error) {
 	return f.info, nil
 }
 
-func (f *File) Close() error {
-	if f.Source == nil {
-		return nil
-	}
-	if c, ok := f.Source.(io.Closer); ok {
-		return c.Close()
-	}
-	return nil
-}
-
 func (f File) Name() string {
 	return f.info.Name()
 }
@@ -174,19 +225,6 @@ func (f File) String() string {
 	return string(b)
 }
 
-func (f *File) Read(p []byte) (int, error) {
-	if f.Source != nil {
-		return f.Source.Read(p)
-	}
-
-	of, err := f.her.Open(f.Path())
-	if err != nil {
-		return 0, err
-	}
-	f.Source = of
-	return f.Source.Read(p)
-}
-
 // Readdir reads the contents of the directory associated with file and returns a slice of up to n FileInfo values, as would be returned by Lstat, in directory order. Subsequent calls on the same file will yield further FileInfos.
 //
 // If n > 0, Readdir returns at most n FileInfo structures. In this case, if Readdir returns an empty slice, it will return a non-nil error explaining why. At the end of a directory, the error is io.EOF.
diff --git a/file_test.go b/file_test.go
index 78a25ee..08ee4a9 100644
--- a/file_test.go
+++ b/file_test.go
@@ -1,7 +1,9 @@
 package pkger
 
 import (
+	"io"
 	"io/ioutil"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -31,3 +33,48 @@ func Test_File_Open_Dir(t *testing.T) {
 
 	r.NoError(f.Close())
 }
+
+func Test_File_Read_Memory(t *testing.T) {
+	r := require.New(t)
+
+	f, err := Open("/file_test.go")
+	r.NoError(err)
+	f.data = []byte("hi!")
+
+	r.Equal("file_test.go", f.Name())
+
+	b, err := ioutil.ReadAll(f)
+	r.NoError(err)
+	r.Equal(string(b), "hi!")
+	r.NoError(f.Close())
+}
+
+func Test_File_Write(t *testing.T) {
+	r := require.New(t)
+
+	i := newIndex()
+
+	f, err := i.Create(Path{
+		Name: "/hello.txt",
+	})
+	r.NoError(err)
+	r.NotNil(f)
+
+	fi, err := f.Stat()
+	r.NoError(err)
+	r.Zero(fi.Size())
+
+	r.Equal("/hello.txt", fi.Name())
+
+	mt := fi.ModTime()
+	r.NotZero(mt)
+
+	sz, err := io.Copy(f, strings.NewReader(radio))
+	r.NoError(err)
+	r.Equal(int64(1381), sz)
+
+	r.NoError(f.Close())
+	r.Equal(int64(1381), fi.Size())
+	r.NotZero(fi.ModTime())
+	r.NotEqual(mt, fi.ModTime())
+}
diff --git a/http_test.go b/http_test.go
index 4a2ac6e..d5c2e04 100644
--- a/http_test.go
+++ b/http_test.go
@@ -48,3 +48,25 @@ func Test_HTTP_Dir(t *testing.T) {
 
 	r.NoError(f.Close())
 }
+
+func Test_HTTP_File_Memory(t *testing.T) {
+	r := require.New(t)
+
+	i := newIndex()
+	f, err := createFile(i, "/cmd/pkger/main.go")
+
+	r.NoError(err)
+
+	ts := httptest.NewServer(http.FileServer(f))
+	defer ts.Close()
+
+	res, err := http.Get(ts.URL + "/cmd/pkger/main.go")
+	r.NoError(err)
+	r.Equal(200, res.StatusCode)
+
+	b, err := ioutil.ReadAll(res.Body)
+	r.NoError(err)
+	r.Contains(string(b), "I wanna bite the hand that feeds me")
+
+	r.NoError(f.Close())
+}
diff --git a/index.go b/index.go
index a162978..eac5c0e 100644
--- a/index.go
+++ b/index.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	"github.com/gobuffalo/here"
 	"github.com/markbates/pkger/pkgs"
@@ -16,6 +17,26 @@ type index struct {
 	Files map[Path]*File
 }
 
+func (i index) Create(pt Path) (*File, error) {
+	her, err := pkgs.Pkg(pt.Pkg)
+	if err != nil {
+		return nil, err
+	}
+	f := &File{
+		path:  pt,
+		index: newIndex(),
+		her:   her,
+		info: &FileInfo{
+			name:    pt.Name,
+			mode:    0666,
+			modTime: time.Now(),
+		},
+	}
+
+	i.Files[pt] = f
+	return f, nil
+}
+
 func (i index) MarshalJSON() ([]byte, error) {
 	m := map[string]interface{}{
 		"pkg": i.Pkg,
@@ -90,13 +111,11 @@ func (i index) Open(pt Path) (*File, error) {
 		return i.openDisk(pt)
 	}
 	return &File{
-		info: f.info,
-		path: f.path,
-		data: f.data,
-		her:  f.her,
-		index: &index{
-			Files: map[Path]*File{},
-		},
+		info:  f.info,
+		path:  f.path,
+		data:  f.data,
+		her:   f.her,
+		index: newIndex(),
 	}, nil
 }
 
@@ -128,6 +147,35 @@ func (i index) openDisk(pt Path) (*File, error) {
 	return f, nil
 }
 
-var rootIndex = &index{
-	Files: map[Path]*File{},
+func (i index) Parse(p string) (Path, error) {
+	var pt Path
+	res := strings.Split(p, ":")
+
+	if len(res) < 1 {
+		return pt, fmt.Errorf("could not parse %q (%d)", res, len(res))
+	}
+	if len(res) == 1 {
+		if strings.HasPrefix(res[0], "/") {
+			pt.Name = res[0]
+		} else {
+			pt.Pkg = res[0]
+		}
+	} else {
+		pt.Pkg = res[0]
+		pt.Name = res[1]
+	}
+	pt.Name = strings.TrimPrefix(pt.Name, "/")
+	pt.Pkg = strings.TrimPrefix(pt.Pkg, "/")
+	if len(pt.Pkg) == 0 {
+		pt.Pkg = i.Pkg
+	}
+	return pt, nil
 }
+
+func newIndex() *index {
+	return &index{
+		Files: map[Path]*File{},
+	}
+}
+
+var rootIndex = newIndex()
diff --git a/index_test.go b/index_test.go
new file mode 100644
index 0000000..945c14b
--- /dev/null
+++ b/index_test.go
@@ -0,0 +1,63 @@
+package pkger
+
+import (
+	"io"
+	"os"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_index_Create(t *testing.T) {
+	r := require.New(t)
+
+	i := newIndex()
+
+	f, err := i.Create(Path{
+		Name: "/hello.txt",
+	})
+	r.NoError(err)
+	r.NotNil(f)
+
+	fi, err := f.Stat()
+	r.NoError(err)
+
+	r.Equal("/hello.txt", fi.Name())
+	r.Equal(os.FileMode(0666), fi.Mode())
+	r.NotZero(fi.ModTime())
+
+	her := f.her
+	r.NotZero(her)
+	r.Equal("github.com/markbates/pkger", her.ImportPath)
+}
+
+func Test_index_Create_Write(t *testing.T) {
+	r := require.New(t)
+
+	i := newIndex()
+
+	f, err := i.Create(Path{
+		Name: "/hello.txt",
+	})
+	r.NoError(err)
+	r.NotNil(f)
+
+	fi, err := f.Stat()
+	r.NoError(err)
+	r.Zero(fi.Size())
+
+	r.Equal("/hello.txt", fi.Name())
+
+	mt := fi.ModTime()
+	r.NotZero(mt)
+
+	sz, err := io.Copy(f, strings.NewReader(radio))
+	r.NoError(err)
+	r.Equal(int64(1381), sz)
+
+	r.NoError(f.Close())
+	r.Equal(int64(1381), fi.Size())
+	r.NotZero(fi.ModTime())
+	r.NotEqual(mt, fi.ModTime())
+}
diff --git a/internal/examples/extfile/main.go b/internal/examples/extfile/main.go
index 72482ce..b76f955 100644
--- a/internal/examples/extfile/main.go
+++ b/internal/examples/extfile/main.go
@@ -10,7 +10,7 @@ import (
 )
 
 func main() {
-	f, err := pkger.Open("github.com/gobuffalo/buffalo:/server.go")
+	f, err := pkger.Open("github.com/gobuffalo/buffalo:/go.mod")
 	if err != nil {
 		log.Fatal("1", err)
 	}
diff --git a/path.go b/path.go
index af09b40..4411a4d 100644
--- a/path.go
+++ b/path.go
@@ -2,7 +2,6 @@ package pkger
 
 import (
 	"fmt"
-	"strings"
 )
 
 type Path struct {
@@ -21,23 +20,5 @@ func (p Path) String() string {
 }
 
 func Parse(p string) (Path, error) {
-	var pt Path
-	res := strings.Split(p, ":")
-
-	if len(res) < 1 {
-		return pt, fmt.Errorf("could not parse %q (%d)", res, len(res))
-	}
-	if len(res) == 1 {
-		if strings.HasPrefix(res[0], "/") {
-			pt.Name = res[0]
-		} else {
-			pt.Pkg = res[0]
-		}
-	} else {
-		pt.Pkg = res[0]
-		pt.Name = res[1]
-	}
-	pt.Name = strings.TrimPrefix(pt.Name, "/")
-	pt.Pkg = strings.TrimPrefix(pt.Pkg, "/")
-	return pt, nil
+	return rootIndex.Parse(p)
 }
diff --git a/pkger.go b/pkger.go
index aabc11b..607d799 100644
--- a/pkger.go
+++ b/pkger.go
@@ -1,31 +1,6 @@
 package pkger
 
-import (
-	"bytes"
-	"fmt"
-	"os/exec"
-	"path/filepath"
-)
-
-func modRoot() (string, error) {
-	c := exec.Command("go", "env", "GOMOD")
-	b, err := c.CombinedOutput()
-	if err != nil {
-		return "", err
-	}
-
-	b = bytes.TrimSpace(b)
-	if len(b) == 0 {
-		return "", fmt.Errorf("the `go env GOMOD` was empty/modules are required")
-	}
-
-	return filepath.Dir(string(b)), nil
-}
-
-func Getwd() (string, error) {
-	return modRoot()
-}
-
+// Open opens the named file for reading.
 func Open(p string) (*File, error) {
 	pt, err := Parse(p)
 	if err != nil {
@@ -33,3 +8,12 @@ func Open(p string) (*File, error) {
 	}
 	return rootIndex.Open(pt)
 }
+
+// Create creates the named file with mode 0666 (before umask), truncating it if it already exists. If successful, methods on the returned File can be used for I/O; the associated file descriptor has mode O_RDWR. If there is an error, it will be of type *PathError.
+func Create(p string) (*File, error) {
+	pt, err := Parse(p)
+	if err != nil {
+		return nil, err
+	}
+	return rootIndex.Create(pt)
+}
diff --git a/pkger_test.go b/pkger_test.go
new file mode 100644
index 0000000..030c6b4
--- /dev/null
+++ b/pkger_test.go
@@ -0,0 +1,68 @@
+package pkger
+
+import (
+	"io"
+	"strings"
+)
+
+func createFile(i *index, p string, body ...string) (*File, error) {
+	pt, err := i.Parse(p)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(body) == 0 {
+		body = append(body, radio)
+	}
+
+	f, err := i.Create(pt)
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = io.Copy(f, strings.NewReader(strings.Join(body, "\n\n")))
+	if err != nil {
+		return nil, err
+	}
+
+	if err := f.Close(); err != nil {
+		return nil, err
+	}
+	return f, nil
+}
+
+const radio = `I was tuning in the shine on the late night dial
+Doing anything my radio advised
+With every one of those late night stations
+Playing songs bringing tears to my eyes
+I was seriously thinking about hiding the receiver
+When the switch broke 'cause it's old
+They're saying things that I can hardly believe
+They really think we're getting out of control
+Radio is a sound salvation
+Radio is cleaning up the nation
+They say you better listen to the voice of reason
+But they don't give you any choice 'cause they think that it's treason
+So you had better do as you are told
+You better listen to the radio
+I wanna bite the hand that feeds me
+I wanna bite that hand so badly
+I want to make them wish they'd never seen me
+Some of my friends sit around every evening
+And they worry about the times ahead
+But everybody else is overwhelmed by indifference
+And the promise of an early bed
+You either shut up or get cut up; they don't wanna hear about it
+It's only inches on the reel-to-reel
+And the radio is in the hands of such a lot of fools
+Tryin' to anesthetize the way that you feel
+Radio is a sound salvation
+Radio is cleaning up the nation
+They say you better listen to the voice of reason
+But they don't give you any choice 'cause they think that it's treason
+So you had better do as you are told
+You better listen to the radio
+Wonderful radio
+Marvelous radio
+Wonderful radio
+Radio, radio`