diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..5d12634
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,13 @@
+# editorconfig.org
+root = true
+
+[*]
+indent_style = space
+indent_size = 2
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..79d0efb
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.DS_Store
+Thumbs.db
+npm/
+coverage
diff --git a/.vscode/extensions.json b/.vscode/extensions.json
new file mode 100644
index 0000000..09cf720
--- /dev/null
+++ b/.vscode/extensions.json
@@ -0,0 +1,5 @@
+{
+  "recommendations": [
+    "denoland.vscode-deno"
+  ]
+}
diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..45dc064
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,18 @@
+{
+  "deno.enable": true,
+  "deno.lint": true,
+  "deno.codeLens.test": true,
+  "editor.defaultFormatter": "denoland.vscode-deno",
+  "editor.formatOnSave": true,
+  "editor.codeActionsOnSave": {
+    "source.fixAll": true
+  },
+  "deno.inlayHints.enumMemberValues.enabled": false,
+  "deno.inlayHints.functionLikeReturnTypes.enabled": false,
+  "deno.inlayHints.parameterTypes.enabled": false,
+  "deno.inlayHints.propertyDeclarationTypes.enabled": false,
+  "deno.inlayHints.variableTypes.suppressWhenTypeMatchesName": false,
+  "deno.inlayHints.variableTypes.enabled": false,
+  "deno.inlayHints.parameterNames.enabled": "none",
+  "deno.inlayHints.parameterNames.suppressWhenArgumentMatchesName": false
+}
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..797920f
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,20 @@
+MIT License
+
+Copyright (c) 2023 httpland
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
+the Software, and to permit persons to whom the Software is furnished to do so,
+subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
+FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
+COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..e6fbde8
--- /dev/null
+++ b/README.md
@@ -0,0 +1,47 @@
+# http-middleware
+
+HTTP middleware specification
+
+## What
+
+Define standard HTTP middleware specifications. This is intended to increase the
+interoperability of the HTTP library's own middleware.
+
+It consists only of the web standards stack and is compatible with many
+Browsers.
+
+## Interface
+
+Middleware interfaces can be defined in TypeScript as follows:
+
+```ts
+interface Middleware {
+  (request: Request, next: Handler): Response | Promise<Response>;
+}
+
+interface Handler {
+  (request: Request): Response | Promise<Response>;
+}
+```
+
+## Features
+
+`Middleware` has the following features:
+
+- Compatible with `Handler`.
+
+  `Handler` is a powerful interface for handling HTTP requests. The `Middleware`
+  is purely an extension and compatibility with `Handler`.
+
+- It can access to the `Request`.
+- It can access the next handler.
+- It can call the next handler.
+- It can choose not to call the next handler.
+- It can access the next handler's return value (`Response`).
+- It can return `Response`.
+
+## License
+
+Copyright © 2023-present [httpland](https://github.com/httpland).
+
+Released under the [MIT](./LICENSE) license
diff --git a/deno.json b/deno.json
new file mode 100644
index 0000000..567ef77
--- /dev/null
+++ b/deno.json
@@ -0,0 +1,27 @@
+{
+  "tasks": {
+    "test": "deno test --doc",
+    "coverage": "deno coverage",
+    "build:npm": "deno run -A _tools/build_npm.ts"
+  },
+  "fmt": {
+    "files": {
+      "exclude": ["CHANGELOG.md", "CODE_OF_CONDUCT.md"]
+    }
+  },
+  "lint": {
+    "files": {
+      "exclude": ["CHANGELOG.md", "CODE_OF_CONDUCT.md"]
+    }
+  },
+  "test": {
+    "files": {
+      "exclude": ["CHANGELOG.md", "CODE_OF_CONDUCT.md"]
+    }
+  },
+  "compilerOptions": {
+    "noImplicitReturns": true,
+    "noImplicitOverride": true,
+    "noUncheckedIndexedAccess": true
+  }
+}