Prerender API - Win AI search

10/13/2025·by LovableHTML

Prerender your CSR pages into HTML using Cloudflare Worker, Vercel or Netlify functions.

You must own the target domain (added to your LovableHTML account). The API verifies domain ownership before rendering.

Auth header

Send your API key with one of these headers:

x-lovablehtml-api-key: <API_KEY>
Authorization: Bearer <API_KEY>

Create/manage keys in the dashboard.

Render endpoint

GET /api/prerender/render?url=<ENCODED_URL>

Headers (one of):

x-lovablehtml-api-key: <API_KEY>
Authorization: Bearer <API_KEY>

Behavior

If prerendering applies: returns 200 text/html with the page HTML.
If prerendering does not apply (static asset, non-HTML request, or browser navigation): returns 304 with Location header pointing to the target URL.

Notes

Static assets (e.g. .css, .js, images, fonts) are never prerendered. Follow the Location header or fetch directly.
To ensure HTML rendering, send Accept: text/html. The endpoint classifies requests similarly to the built-in prerenderer.

Cloudflare Workers (run for every request via Route)

If your domain is not on Cloudflare yet, add it first
Create a new Worker → choose an 'Hello World' Worker → Deploy → Edit Code
Paste the snippet below and deploy your Worker
If you did not paste a key into the snippet, set a Worker secret named LOVABLEHTML_API_KEY via the dashboard or run: wrangler secret put LOVABLEHTML_API_KEY
Go to your Worker → Settings → Domains & Routes → Add Custom Domain → enter yourdomain.com

Important: Use Custom Domains, not Routes

Custom Domains automatically route all traffic through the worker and manage SSL. Make sure the orange proxy cloud is ON for your domain in the Cloudflare DNS settings. Do not use "Add Route" — routes behave differently and may not intercept traffic correctly.

lovablehtml-prerender.js

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// lovablehtml-prerender.js (Cloudflare Worker)
export default {
  async fetch(req, env) {
    // Only handle public GET navigations
    if (req.method !== 'GET') return fetch(req);

    const isHtmlRequest = (req.headers.get('accept') || '').includes('text/html');
    if (!isHtmlRequest) return fetch(req);

    const headers = new Headers();
    headers.set('x-lovablehtml-api-key', env.LOVABLEHTML_API_KEY);
    headers.set('accept', 'text/html');
    const forward = [
      'accept-language',
      'sec-fetch-mode',
      'sec-fetch-site',
      'sec-fetch-dest',
      'sec-fetch-user',
      'upgrade-insecure-requests',
      'referer',
      'user-agent',
    ];
    for (const name of forward) {
      const v = req.headers.get(name);
      if (v) headers.set(name, v);
    }

    const r = await fetch('https://lovablehtml.com/api/prerender/render?url=' + encodeURIComponent(req.url), { headers });

    // 304 = not pre-rendered, pass through to origin
    if (r.status === 304) {
      return fetch(req);
    }
    if ((r.headers.get('content-type') || '').includes('text/html')) {
      return new Response(await r.text(), { headers: { 'content-type': 'text/html; charset=utf-8' } });
    }
    return fetch(req);
  },
};

Vercel Middleware (run before every request)

Create middleware.js at the project root (same level as package.json).
Set the environment variable LOVABLEHTML_API_KEY in your Vercel project settings if you did not paste a key into the snippet.
Deploy to Vercel. The middleware runs on the configured matcher for every request.

middleware.js

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// middleware.js (place at the project root next to package.json)
export const config = {
  // Use Node.js runtime to access standard Request/Response
  runtime: 'nodejs',
  // Run on all paths except static assets (customize for your app)
  matcher: [
    '/((?!_some-static-path|favicon.ico).*)',
    // You can also be explicit:
    // '/:path*'
  ],
};

import { next } from "@vercel/functions"; // <- npm install @vercel/functions

export default async function middleware(request) {
  const isHtmlRequest = (request.headers.get("accept") || "").includes(
    "text/html"
  );

  // 2. If it's not a GET request or not HTML, pass through (e.g. API routes)
  if (request.method !== "GET" || !isHtmlRequest) {
    return next();
  }

  try {
    // Forward relevant headers and add custom ones
    const headers = {
      "x-lovablehtml-api-key": <your-api-key>,

      accept: "text/html",
      "accept-language": request.headers.get("accept-language") || "",
      "sec-fetch-mode": request.headers.get("sec-fetch-mode") || "",
      "sec-fetch-site": request.headers.get("sec-fetch-site") || "",
      "sec-fetch-dest": request.headers.get("sec-fetch-dest") || "",
      "sec-fetch-user": request.headers.get("sec-fetch-user") || "",
      "upgrade-insecure-requests":
        request.headers.get("upgrade-insecure-requests") || "",
      referer: request.headers.get("referer") || "",
      "user-agent": request.headers.get("user-agent") || "",
    };

    // Call LovableHTML prerender service with the full URL
    const r = await fetch(
      "https://lovablehtml.com/api/prerender/render?url=" +
        encodeURIComponent(request.url),
      { headers }
    );

    // not pre-rendered, regular browser routing - pass through to SPA
    if (r.status === 304) {
      return next();
    }

    // Return HTML or fall through
    if ((r.headers.get("content-type") || "").includes("text/html")) {
      return new Response(r.body, {
        headers: { "content-type": "text/html; charset=utf-8" },
      });
    }
  } catch {
    // ignore
  }

  // Safety fallback: never block the request
  return next();
};

Netlify Edge Functions (attach to /*)

Create the Edge Function file at netlify/edge-functions/lovablehtml.js
Set the environment variable LOVABLEHTML_API_KEY in your Netlify site settings if you did not paste a key into the snippet.
Deploy to Netlify. The edge function runs on every request and forwards bot traffic to the pre-rendering API.

lovablehtml.js

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// netlify/edge-functions/lovablehtml.js (Netlify Edge Function)
export default async (request, context) => {
  // Only handle public GET navigations
  const isHtmlRequest = (request.headers.get('accept') || '').includes('text/html');
  if (request.method !== 'GET' || !isHtmlRequest) return context.next();

  const headers = {
    'x-lovablehtml-api-key': <your-api-key>,
    accept: 'text/html',
    'accept-language': request.headers.get('accept-language') || '',
    'sec-fetch-mode': request.headers.get('sec-fetch-mode') || '',
    'sec-fetch-site': request.headers.get('sec-fetch-site') || '',
    'sec-fetch-dest': request.headers.get('sec-fetch-dest') || '',
    'sec-fetch-user': request.headers.get('sec-fetch-user') || '',
    'upgrade-insecure-requests': request.headers.get('upgrade-insecure-requests') || '',
    referer: request.headers.get('referer') || '',
    'user-agent': request.headers.get('user-agent') || '',
  };

  const r = await fetch('https://lovablehtml.com/api/prerender/render?url=' + encodeURIComponent(request.url), { headers });

  // 304 = not pre-rendered, pass through to origin
  if (r.status === 304) {
    return context.next();
  }

  if ((r.headers.get('content-type') || '').includes('text/html')) {
    return new Response(await r.text(), { headers: { 'content-type': 'text/html; charset=utf-8' } });
  }

  return context.next();
};

export const config = {
  path: "/*",
};

Errors

401 missing_api_key / invalid_api_key
403 domain_not_owned
200 text/html on success
304 with Location header when prerendering not applicable

Best practices

Keep API keys secret; rotate/revoke when compromised.
Always send Accept: text/html for bots/crawlers to maximize prerender chance.

Cache invalidation endpoints

These endpoints purge prerendered sources of pages for domains you own. Optionally prewarm to immediately re-render. Authentication is the same as the render endpoint (API key header).

POST `/api/prerender/cache/invalidate-page-cache`

Body:

json

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{
  "domain": "example.com",
  "path": "/pricing",
  "prewarm": true
}

Response:

json

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{ "ok": true, "prewarmed": 1 }

Example:

bash

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curl -sS \
  -X POST \
  -H "content-type: application/json" \
  -H "x-lovablehtml-api-key: <API_KEY>" \
  -d '{"domain":"example.com","path":"/pricing","prewarm":true}' \
  https://<your-dashboard-host>/api/prerender/cache/invalidate-page-cache

POST `/api/prerender/cache/invalidate-paths-cache`

Body:

json

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{
  "domain": "example.com",
  "paths": ["/", "/pricing", "/blog/post"],
  "prewarm": true
}

Response:

json

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{ "ok": true, "prewarmed": 3 }

Example:

bash

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curl -sS \
  -X POST \
  -H "content-type: application/json" \
  -H "x-lovablehtml-api-key: <API_KEY>" \
  -d '{"domain":"example.com","paths":["/","/pricing","/blog/post"],"prewarm":true}' \
  https://<your-dashboard-host>/api/prerender/cache/invalidate-paths-cache

POST `/api/prerender/cache/invalidate-site-cache`

Body:

json

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{ "domain": "example.com" }

Response:

json

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{ "ok": true, "accepted": true }

Example:

bash

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curl -sS \
  -X POST \
  -H "content-type: application/json" \
  -H "x-lovablehtml-api-key: <API_KEY>" \
  -d '{"domain":"example.com","prewarm":true}' \
  https://<your-dashboard-host>/api/prerender/cache/invalidate-site-cache

Notes

The API validates that the domain belongs to the authenticated user.
prewarm: true deletes the old cache and immediately re-renders the path(s).
Common variants (with/without trailing slash) are handled automatically.

API Collections & Integrations

Explore and test the Prerender API using these platforms:

Postman Collection - Interactive API documentation with request examples
APIDog Collection - Alternative API testing and documentation
RapidAPI - Marketplace listing for the Prerendering API

Auth header

Render endpoint

Behavior

Notes

Cloudflare Workers (run for every request via Route)

Vercel Middleware (run before every request)

Netlify Edge Functions (attach to /*)

Errors

Best practices

Cache invalidation endpoints

POST /api/prerender/cache/invalidate-page-cache

POST /api/prerender/cache/invalidate-paths-cache

POST /api/prerender/cache/invalidate-site-cache

Notes

API Collections & Integrations

POST `/api/prerender/cache/invalidate-page-cache`

POST `/api/prerender/cache/invalidate-paths-cache`

POST `/api/prerender/cache/invalidate-site-cache`