Image Templates
Generate images
from a URL
Define a template once. Render thousands of personalised images at the edge — OG cards, social banners, product images, certificates — in under 50ms via CDN URL. No queues, no Puppeteer, no separate service.
It's just a URL
Variables in the URL override template defaults. The result is cached globally — identical URLs hit the CDN edge, not the renderer.
Use cases
One renderer, every image generation need.
Open Graph images
Personalised OG images for every blog post, product, or user profile. Update the title param in the URL.
/render/og-card?title=Hello+World&author=SeanSocial banners
Twitter/LinkedIn cards with dynamic text and images. One template, infinite variations.
/render/social-banner?product=Widget+Pro&price=$49Product cards
Auto-generated product images for e-commerce feeds, email, and ads with live product data.
/render/product-card?name=Sneakers&image=product.jpgEmail headers
Personalised email header images with customer name, offer, or dynamic content.
/render/email-header?name=Alice&offer=20%25+offCertificates
Award certificates and completion badges with recipient name and date rendered on the fly.
/render/certificate?name=Alice+Smith&course=ReactQR codes with branding
Branded images with embedded QR codes — combine logo, text, and QR in one URL.
/render/qr-card?url=https://example.com&title=Scan+meLayer types
Templates are JSON. Layers compose like a design tool — rendered at the edge by a Rust/WASM engine using tiny-skia and cosmic-text.
textRendered text with font, size, weight, colour, alignment, and word-wrap
imageExternal image with cover/contain/fill fit and rounded corners
rectRectangle with fill colour, rounded corners, and optional border
circleCircle with fill colour and optional border
gradientLinear gradient overlay — top-to-bottom, left-to-right, and more
qrQR code from any data string, with custom foreground and background colours
Templates are just JSON
Define width, height, background, and a layers array. Variables use {{variable}} syntax anywhere in string fields. Create templates via dashboard, API, or MCP tool.
- ✓Variable substitution in any string field
- ✓Layers rendered in order (painter's algorithm)
- ✓Output cached by URL — same inputs = CDN hit
- ✓Outputs WebP, AVIF, JXL, or PNG
{
"width": 1200,
"height": 630,
"background": {
"type": "solid",
"color": "#0a0a0c"
},
"layers": [
{
"type": "rect",
"x": 0, "y": 0,
"w": 1200, "h": 630,
"fill": "#5340FA",
"opacity": 15
},
{
"type": "text",
"content": "{{title}}",
"x": 80, "y": 200,
"font": "Inter",
"size": 64,
"weight": 700,
"color": "#ffffff"
},
{
"type": "text",
"content": "by {{author}}",
"x": 80, "y": 300,
"size": 28,
"color": "#a1a1aa"
}
],
"variables": [
{ "name": "title", "type": "text",
"default": "Untitled" },
{ "name": "author", "type": "text",
"default": "Spronta" }
]
}vs Bannerbear, Satori, and Cloudinary
Stop paying $49–$399/mo for a separate image generation SaaS. Spronta bakes it into the CDN you're already using.
| Product | Price | Latency | Formats |
|---|---|---|---|
| Bannerbear | $49–$399/mo | 2–5 seconds | PNG only |
| Vercel OG / Satori | Included in Vercel | ~500ms cold start | PNG only |
| Cloudinary Dynamic Images | Usage-based ($89+/mo) | ~200ms (CDN) | JPEG, PNG, WebP |
| Spronta Templates | Included in CDN plan | <50ms | WebP, AVIF, JXL, PNG |
Create templates via API, SDK, or MCP
Build your template design workflow however you want.
REST API
POST /api/images/projects/:id/templatesMCP Tool
create_template { name, template, variables }Render URL
render_template_url { templateName, variables }Stop paying for Bannerbear
Image templates are included in every Spronta plan — same CDN, same API key, no extra invoice.