Creating Share Images for Next.js

Generate dynamic OpenGraph (1200x630) and Twitter (1200x600) images using next/og ImageResponse.

Choosing an Approach

• File-based route (app/opengraph-image.tsx): Best for static pages with known titles at build time. Export runtime, alt, size, contentType, and a default Image function.
• API route (app/api/og/route.tsx): Best for dynamic content (blog posts, CMS). Accept slug and/or title as query params. Reference in metadata via generateMetadata().

Use export const runtime = "edge" for both approaches.

File Naming Convention

Place file-based routes in the relevant route directory (e.g., app/about/opengraph-image.tsx for /about).

Layout Pattern

• Use flexDirection: "column" with justifyContent: "space-between" to separate content from branding
• Title and subtitle (e.g., author name) go top-left in a stacked flex column
• Title: large, bold/medium weight, dark color
• Subtitle: same size or smaller, lighter weight, muted color (e.g., #888)
• Keep text left-aligned with textWrap: "balance" and constrain width with maxWidth
• Use letterSpacing: "-0.02em" for tight, editorial feel at large sizes
• Padding: 48px on all sides works well at 1200x630

Avatar / Logo (Optional)

If the project has an avatar or logo, place it in the bottom-right corner using a flex container with justifyContent: "flex-end". Load images via fetch + arrayBuffer, convert to base64 data URI for the src. Use borderRadius: "50%" for circular avatars. Cache loaded assets in a Map to avoid refetching.

Custom Fonts

Load .ttf files from public/fonts/ using new URL("../../../public/fonts/YourFont.ttf", import.meta.url). Pass the ArrayBuffer to ImageResponse via the fonts option. Cache the font buffer after first load. Match the weight in the fonts config to the actual font file weight.

Title Case

If titles come from a CMS, apply smart title case:

• Lowercase small words (a, an, the, and, but, for, in, of, etc.) unless first or last
• Always capitalize brand names correctly (WordPress, JavaScript, GitHub, macOS, etc.)
• Uppercase known acronyms (AI, API, CSS, HTML, UI, UX)
• Handle hyphenated words by capitalizing each part independently

Metadata Integration

Reference the OG route in generateMetadata():

export function generateMetadata({ params }) {
  return {
    openGraph: {
      images: [`/api/og?slug=${params.slug}`],
    },
  };
}

For static pages, pass the title directly: /api/og?title=About.

Satori Rules

These are hard requirements of the next/og rendering engine (Satori):

1. Every element needs display: "flex" — this is the only layout mode
2. Inline styles only — no CSS classes, no external stylesheets, no CSS variables
3. All text must be in elements with explicit style props
4. Use hex colors — no rgb(), hsl(), or CSS variables
5. No gap on older versions — test before relying on it; fallback to margin

Common Issues

Testing

Preview during development by visiting the route directly in the browser:

http://localhost:3000/api/og?title=Hello+World

After building, verify routes register as dynamic (f prefix) in the build output.