How is the hosted render URL secured?

The URL carries an HMAC signature over its parameters — the signature is the auth boundary, so the link renders only the exact params you signed and can't be tampered with. No API key is exposed in the URL.

Do repeat crawls cost me credits?

No. Identical requests resolve to a deterministic cache key in Rendex's R2, so after the first render every fetch is served from cache and doesn't count against your monthly quota. You're billed only when the card is actually (re)rendered.

How long does the signed URL stay valid?

You choose. Set expiresIn (seconds) when minting the link to control its lifetime, and cacheTtl to control how long the rendered asset is cached — anywhere from one hour up to 30 days.

Can I template the card per page or per user?

Yes. Render from a unique URL, or send raw HTML or Markdown with {{data}} values so each card shows the right title, price, or name. The response is a fresh signed URL you embed in that page's og:image tag.

Use Case

Dynamic OG Images from a URL You Paste Into <meta>

Call /v1/render/link, get back a signed URL, and drop it into <meta og:image> or an <img> tag. Rendex renders the card the first time it's fetched, caches the bytes on the edge, and serves every repeat crawl from cache — no image hosting, no storage bucket, no re-render bill.

Get Free API Key Try Free Tool View API Docs

The Problem

Dynamic social cards normally mean rendering an image, uploading it to S3 or R2, wiring a CDN, and tracking when to invalidate — all before a single crawler sees it. For a no-code stack or a static site, standing up that storage-and-hosting pipeline just to power <meta og:image> is far more infrastructure than the feature is worth.

The Solution

Rendex hosts the render for you. POST your capture params — a URL, raw HTML, or Markdown with {{data}} templating — to /v1/render/link and get back a self-contained signed URL plus its expiry. Paste it into <meta og:image>: the first crawl renders and caches it in Rendex's R2 under a deterministic key, so identical requests serve straight from cache and don't re-charge you. Prefer the binary endpoint? Set hosted: true on /v1/screenshot to get {url, expiresAt} back instead of raw bytes.

See it in action

A render-link request with a title and tag on the left, and the cached Rendex-rendered Open Graph social card it produces on the right.

Get Started in Minutes

render-link.sh

curl -s -X POST https://api.rendex.dev/v1/render/link \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "html": "<h1>{{title}}</h1>",
    "data": { "title": "Launch day" },
    "format": "png", "width": 1200, "height": 630
  }'
# => { "url": "https://api.rendex.dev/v1/render?p=...&sig=...", "expiresAt": "..." }

render-link.js

import Rendex from "@copperline/rendex";

const rendex = new Rendex("YOUR_API_KEY");

// Mint one signed URL per page — render it from a URL, HTML, or Markdown.
const { url, expiresAt } = await rendex.renderLink({
  url: "https://example.com/product/42",
  format: "png",
  width: 1200,
  height: 630,
});

// In your page <head>:
//   <meta property="og:image" content={url} />
console.log(url, expiresAt);

render_link.py

from rendex import Rendex

rendex = Rendex("YOUR_API_KEY")

# Render once, host on the edge, embed the signed URL anywhere.
link = rendex.render_link(
    url="https://example.com/product/42",
    format="png",
    width=1200,
    height=630,
)

# Drop link["url"] into <meta property="og:image" content="...">
print(link["url"], link["expiresAt"])

100 free API calls/month — no credit card required. Get your API key and start building.

Built for This Use Case

A URL You Can Paste Into <meta>

/v1/render/link returns a self-contained signed URL. No SDK required at render time — any crawler, CMS, or email client just fetches it like a normal image.

Renders on First Hit

The card is rendered the first time the signed URL is fetched, then served as a static asset. Your app never has to call the API on the request path.

Edge-Cached, No Re-Charge

Identical params map to a deterministic R2 cache key, so repeat crawls serve cached bytes and don't count against your quota — only the first render bills.

HTML, Markdown & Templating

Render from a live URL or build the card yourself with raw HTML or Markdown plus {{data}} templating — perfect for per-post, per-product, or per-user cards.

Set Your Own TTL

Control how long the signed URL stays valid with expiresIn, and how long the asset is cached with cacheTtl — from an hour to 30 days.

Zero Backend Required

No bucket to provision, no CDN to wire, no invalidation to manage. Available on every plan, including Free — ideal for static sites and no-code stacks.

Start Free, Scale as You Grow

100 calls/month free. Starter at $69/mo for 10K calls (or $58/mo billed annually — 2 months free). Pro at $179/mo for 100K calls.