npm install express ytdl-core fs

const express = require("express");

const ytdl = require("ytdl-core");

const fs = require("fs");

const app = express();

const PORT = 3000;

// Set default video quality (change itag if needed)

const VIDEO_ITAG = "248"; // 1080p WebM

app.get("/download", async (req, res) => {

    try {

        let videoInput = req.query.video;

        if (!videoInput) {

            return res.status(400).json({ error: "Missing 'video' parameter" });

        }

        // If only video ID is given, construct the full URL

        if (!videoInput.startsWith("http")) {

            videoInput = `https://www.youtube.com/watch?v=${videoInput}`;

        }

        // Validate URL

        if (!ytdl.validateURL(videoInput)) {

            return res.status(400).json({ error: "Invalid YouTube video ID or URL" });

        }

        // Get video info

        const info = await ytdl.getInfo(videoInput);

        const format = ytdl.chooseFormat(info.formats, { quality: VIDEO_ITAG });

        if (!format || !format.url) {

            return res.status(500).json({ error: "No downloadable format found" });

        }

        // Prepare filename

        const outputFilePath = `${info.videoDetails.title.replace(/[/\\?%*:|"<>]/g, "")}.${format.container}`;

        const outputStream = fs.createWriteStream(outputFilePath);

        // Download video

        ytdl.downloadFromInfo(info, { format }).pipe(outputStream);

        outputStream.on("finish", () => {

            console.log(`Downloaded: ${outputFilePath}`);

        });

        // Return JSON response

        res.json({

            title: info.videoDetails.title,

            download_link: format.url,

            format: format.mimeType,

            quality: format.qualityLabel

        });

    } catch (error) {

        console.error("Error retrieving video:", error);

        res.status(500).json({

            error: "Error retrieving video information",

            details: error.message

        });

    }

});

app.listen(PORT, () => {

    console.log(`Server is running on http://localhost:${PORT}`);

});

http://localhost:3000/download?video=https://www.youtube.com/watch?v=dQw4w9WgXcQ