Integration

Build a link preview API with Express.

Keep URL fetching on the server, return typed metadata to the browser, and cache successful previews so repeated page views do not repeat outbound work.

Create the endpoint

npm install express linkpeek

import express from "express";
import { preview } from "linkpeek";

const app = express();

app.get("/api/preview", async (request, response) => {
	const url = request.query.url;
	if (typeof url !== "string") {
		response.status(400).json({ error: "Missing url" });
		return;
	}

	try {
		const result = await preview(url);
		response
			.set("Cache-Control", result.statusCode < 400
				? "public, max-age=300"
				: "no-store")
			.json(result);
	} catch {
		response.status(422).json({ error: "Preview unavailable" });
	}
});

The endpoint accepts one URL and returns the stable PreviewResult shape used by a client-side preview card.

Cache successes by normalized URL

The response header helps browsers and shared proxies, but a server-side cache avoids the outbound fetch even when clients miss. Normalize equivalent URLs into one key, coalesce concurrent misses, choose a product-appropriate TTL, and skip caching when statusCode is 400 or higher.

Protect a public preview route

• Add authentication or rate limiting before accepting public traffic.
• Keep allowPrivateIPs disabled for untrusted input.
• Never forward caller cookies, authorization headers, or internal tokens.
• Treat returned titles, descriptions, images, and links as untrusted data.
• Use infrastructure egress rules when the endpoint faces hostile traffic.