diff --git a/README.md b/README.md
index 10bc317..d2e32cd 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,43 @@
 # hashdir
-Generate hash for folder structure
+
+Generate hash of all files and they paths for specified directory.
+
+```go
+package main
+
+import (
+	"fmt"
+
+	"github.com/gosimple/hashdir"
+)
+
+func main() {
+	dirHash, err := hashdir.Make("./someDir/", "md5")
+	fmt.Println(dirHash)
+}
+```
+
+Supported hashes:
+
+* md5
+* sha1
+* sha256
+* sha512
+
+### Requests or bugs?
+
+<https://github.com/gosimple/hashdir/issues>
+
+## Installation
+
+```sh
+go get -u github.com/gosimple/hashdir
+```
+
+## License
+
+The source files are distributed under the
+[Mozilla Public License, version 2.0](http://mozilla.org/MPL/2.0/),
+unless otherwise noted.
+Please read the [FAQ](http://www.mozilla.org/MPL/2.0/FAQ.html)
+if you have further questions regarding the license.
diff --git a/assets/one_more/testowe3.txt b/assets/one_more/testowe3.txt
new file mode 100644
index 0000000..2be9c46
--- /dev/null
+++ b/assets/one_more/testowe3.txt
@@ -0,0 +1 @@
+My insides are ready to check ;)
diff --git a/assets/testowe.txt b/assets/testowe.txt
new file mode 100644
index 0000000..0774e36
--- /dev/null
+++ b/assets/testowe.txt
@@ -0,0 +1 @@
+check me
diff --git a/assets/testowe2.txt b/assets/testowe2.txt
new file mode 100644
index 0000000..87001f3
--- /dev/null
+++ b/assets/testowe2.txt
@@ -0,0 +1 @@
+Don't forget about checking me :(
diff --git a/doc.go b/doc.go
new file mode 100644
index 0000000..dad30c8
--- /dev/null
+++ b/doc.go
@@ -0,0 +1,29 @@
+// Copyright 2020 by Dobrosław Żybort. All rights reserved.
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+/*
+Package hashdir generate hash of all files and they paths for specified
+directory.
+
+Example:
+
+	package main
+
+	import (
+		"fmt"
+
+		"github.com/gosimple/hashdir"
+	)
+
+	func main() {
+		dirHash, err := hashdir.Make("./someDir/", "md5")
+		fmt.Println(dirHash)
+	}
+
+Requests or bugs?
+
+https://github.com/gosimple/hashdir/issues
+*/
+package hashdir
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..8bb29c6
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.org/gosimple/hashdir
+
+go 1.14
diff --git a/hashdir.go b/hashdir.go
new file mode 100644
index 0000000..05b2ae2
--- /dev/null
+++ b/hashdir.go
@@ -0,0 +1,123 @@
+package hashdir
+
+import (
+	"crypto/md5"
+	"crypto/sha1"
+	"crypto/sha256"
+	"crypto/sha512"
+	"encoding/hex"
+	"errors"
+	"hash"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// Make generate hash of all files and they paths for specified directory.
+func Make(dir string, hashType string) (string, error) {
+	var endHash string
+
+	bigErr := filepath.Walk(dir,
+		func(path string, info os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			endHash, err = hashData(endHash, hashType)
+			if err != nil {
+				return err
+			}
+
+			if !info.IsDir() {
+				pathHash, err := hashData(path, hashType)
+				if err != nil {
+					return err
+				}
+				fileHash, err := hashFile(path, hashType)
+				if err != nil {
+					return err
+				}
+				// log.Println(path, fileHash, info.ModTime())
+				endHash = endHash + pathHash + fileHash
+			}
+			return nil
+		})
+
+	if bigErr != nil {
+		return "", bigErr
+	}
+	endHash, err := hashData(endHash, hashType)
+	if err != nil {
+		return "", err
+	}
+	return endHash, err
+}
+
+func selectHash(hashType string) (hash.Hash, error) {
+	switch strings.ToLower(hashType) {
+	case "md5":
+		return md5.New(), nil
+	case "sha1":
+		return sha1.New(), nil
+	case "sha256":
+		return sha256.New(), nil
+	case "sha512":
+		return sha512.New(), nil
+	}
+	return nil, errors.New("Unknown hash: " + hashType)
+}
+
+func hashData(data string, hashType string) (string, error) {
+	h, err := selectHash(hashType)
+	if err != nil {
+		return "", err
+	}
+
+	_, err = h.Write([]byte(data))
+	if err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+func hashFile(path string, hashType string) (string, error) {
+	// Handle hashing big files.
+	// Source: https://stackoverflow.com/q/60328216/1722542
+
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+
+	defer func() {
+		_ = f.Close()
+	}()
+
+	buf := make([]byte, 1024*1024)
+	h, err := selectHash(hashType)
+	if err != nil {
+		return "", err
+	}
+
+	for {
+		bytesRead, err := f.Read(buf)
+		if err != nil {
+			if err != io.EOF {
+				return "", err
+			}
+			_, err = h.Write(buf[:bytesRead])
+			if err != nil {
+				return "", err
+			}
+			break
+		}
+		_, err = h.Write(buf[:bytesRead])
+		if err != nil {
+			return "", err
+		}
+	}
+
+	fileHash := hex.EncodeToString(h.Sum(nil))
+	return fileHash, nil
+}
diff --git a/hashdir_test.go b/hashdir_test.go
new file mode 100644
index 0000000..91c092a
--- /dev/null
+++ b/hashdir_test.go
@@ -0,0 +1,83 @@
+package hashdir
+
+import "testing"
+
+func TestMake(t *testing.T) {
+	type args struct {
+		root     string
+		hashType string
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    string
+		wantErr bool
+	}{
+		{
+			"Test making MD5 hash",
+			args{
+				"./assets/",
+				"md5",
+			},
+			"2d03afa7a1d8e7de98ce8a56660f86ff",
+			false,
+		},
+		{
+			"Test making SHA1 hash",
+			args{
+				"./assets/",
+				"SHA1",
+			},
+			"6049fcf8e09f83a28d769f8493b2af35a0824886",
+			false,
+		},
+		{
+			"Test making SHA256 hash",
+			args{
+				"./assets/",
+				"sha256",
+			},
+			"a7da71b33ec7ce8179b6d47cab465e0b51e581de8086c9e3d7f4e71ee36a39fd",
+			false,
+		},
+		{
+			"Test making SHA512 hash",
+			args{
+				"./assets/",
+				"SHA512",
+			},
+			"5427e699678230eb1a813691d1e7925e5549ad1541bf3e380e7a8267d13fad331873ccb90ebba10f54713653b0fdd82d14532ff956e17519e557790e8c477dcf",
+			false,
+		},
+		{
+			"Test making with wrong hash name",
+			args{
+				"./assets/",
+				"unknownHash",
+			},
+			"",
+			true,
+		},
+		{
+			"Test non existing folder",
+			args{
+				"./someDir/",
+				"md5",
+			},
+			"",
+			true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := Make(tt.args.root, tt.args.hashType)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("Make() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("Make() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}