diff --git a/.eslintrc.json b/.eslintrc.json
index aff8587..15694bd 100644
--- a/.eslintrc.json
+++ b/.eslintrc.json
@@ -15,7 +15,6 @@
 				"browser": false
 			},
 			"rules": {
-				"unicorn/prefer-module": 0,
 				"unicorn/prefer-node-protocol": 0
 			}
 		}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae79fe7..d8cd8d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,17 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 
 ## [v3 (unreleased)][Unreleased]
 
+
+### ⚠️ BREAKING CHANGES
+
+- **new API endpoint path**: ~~`/api/toot`~~ → `/api/share`
+- API endpoint **is now ESM-based** instead of CommonJS
+
+### Added
+
+- when developing, the API endpoint can now be tested locally thanks to
+  [`vite-plugin-node`](https://github.com/axe-me/vite-plugin-node)
+
 ### Changed
 
 - **new project name**: Share₂Fedi (see #1)
diff --git a/api/toot.js b/api/share.js
similarity index 52%
rename from api/toot.js
rename to api/share.js
index 1f26b43..2b075df 100644
--- a/api/toot.js
+++ b/api/share.js
@@ -18,24 +18,28 @@
 	SPDX-License-Identifier: AGPL-3.0-or-later
 */
 
-const http = require("http");
+import http from "http";
 
-http
-	.createServer(async (request, response) => {
-		const buffers = [];
-		for await (const chunk of request) {
-			buffers.push(chunk);
-		}
-		const data = Buffer.concat(buffers).toString();
-		const searchParameters = new URLSearchParams(data);
+const requestListener = async (request, response) => {
+	const buffers = [];
+	for await (const chunk of request) {
+		buffers.push(chunk);
+	}
+	const data = Buffer.concat(buffers).toString();
+	const searchParameters = new URLSearchParams(data);
 
-		const text = searchParameters.get("text") || "";
-		const instanceURL =
-			searchParameters.get("instance") || "https://mastodon.social/";
+	const text = searchParameters.get("text") || "";
+	const instanceURL =
+		searchParameters.get("instance") || "https://mastodon.social/";
 
-		const finalURL = new URL("share", instanceURL);
-		finalURL.search = new URLSearchParams({ text }).toString();
+	const finalURL = new URL("share", instanceURL);
+	finalURL.search = new URLSearchParams({ text }).toString();
 
-		response.writeHead(303, { Location: finalURL.toString() }).end();
-	})
-	.listen(8000);
+	response.writeHead(303, { Location: finalURL.toString() }).end();
+};
+
+if (!import.meta.env || import.meta.env.PROD) {
+	http.createServer(requestListener).listen(8080);
+}
+
+export const viteNodeApp = requestListener;
diff --git a/index.html b/index.html
index f8ef5b9..427dee7 100644
--- a/index.html
+++ b/index.html
@@ -52,7 +52,7 @@
 			</p>
 		</header>
 		<main>
-			<form id="js-s2f-form" action="/api/toot" method="POST">
+			<form id="js-s2f-form" action="/api/share" method="POST">
 				<section>
 					<label for="text">Post text</label>
 					<textarea