OG Images in Vanilla Node.js (No Framework)

Generate OG images without a framework using FastOG's credit-based API — sign up free for 100 credits (create your API key in the dashboard). Skip the boilerplate, preview in the Free OG Image Tester, and build dynamic Open Graph images with plain Node.js and HMAC-signed URLs.

Signer Module

javascript
// og-signer.js
const crypto = require("crypto");
const { URL } = require("url");

function generateSignedOgUrl(params, options = {}) {
    const {
        baseUrl = "https://fastog.com/api/v1/og",
        apiKey = process.env.FASTOG_API_KEY,
        hmacSecret = process.env.FASTOG_HMAC_SECRET,
    } = options;

    const timestamp = Math.floor(Date.now() / 1000);
    const url = new URL(baseUrl);

    for (const [key, value] of Object.entries(params)) {
        url.searchParams.set(key, value);
    }

    const apiKey = apiKey;
    const path = url.pathname;
    const message = `GET${path}${timestamp}${apiKey}`;
    const signature = crypto
        .createHmac("sha256", hmacSecret)
        .update(message)
        .digest("hex");

    url.searchParams.set("key", apiKey);
    url.searchParams.set("s", signature);
    url.searchParams.set("t", timestamp);

    return url.toString();
}

module.exports = { generateSignedOgUrl };

Usage

javascript
// index.js
const { generateSignedOgUrl } = require("./og-signer");

const ogUrl = generateSignedOgUrl({
    template: "blog",
    title: "My Blog Post",
});

console.log("OG Image URL:", ogUrl);

With HTTP Server

javascript
// server.js
const http = require("http");
const { generateSignedOgUrl } = require("./og-signer");

const server = http.createServer((req, res) => {
    if (req.url === "/api/og") {
        const url = new URL(req.url, `http://${req.headers.host}`);
        const title = url.searchParams.get("title");

        if (!title) {
            res.writeHead(400, { "Content-Type": "application/json" });
            return res.end(JSON.stringify({ error: "Missing title" }));
        }

        const ogUrl = generateSignedOgUrl({
            template: "default",
            title,
        });

        res.writeHead(200, { "Content-Type": "application/json" });
        res.end(JSON.stringify({ ogImageUrl: ogUrl }));
        return;
    }

    res.writeHead(404);
    res.end("Not Found");
});

server.listen(3000, () => {
    console.log("Server running on http://localhost:3000");
});

ES Modules Version

javascript
// og-signer.mjs
import crypto from "crypto";
import { URL } from "url";

export function generateSignedOgUrl(params, options = {}) {
    const {
        baseUrl = "https://fastog.com/api/v1/og",
        apiKey = process.env.FASTOG_API_KEY,
        hmacSecret = process.env.FASTOG_HMAC_SECRET,
    } = options;

    const timestamp = Math.floor(Date.now() / 1000);
    const url = new URL(baseUrl);

    for (const [key, value] of Object.entries(params)) {
        url.searchParams.set(key, value);
    }

    const apiKey = apiKey;
    const message = `GET${url.pathname}${timestamp}${apiKey}`;
    const signature = crypto
        .createHmac("sha256", hmacSecret)
        .update(message)
        .digest("hex");

    url.searchParams.set("key", apiKey);
    url.searchParams.set("s", signature);
    url.searchParams.set("t", timestamp);

    return url.toString();
}
javascript
// index.mjs
import { generateSignedOgUrl } from "./og-signer.mjs";

const ogUrl = generateSignedOgUrl({
    template: "blog",
    title: "Hello World",
});

Environment Variables

bash
# .env
FASTOG_API_KEY=sk_your_full_api_key_here
FASTOG_HMAC_SECRET=your_64_char_hex_secret_here

Full API Reference

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