Self-hosted Open Graph image generator: an HTTP API that renders social preview cards (GET /og?title=...&theme=... → PNG) with satori and @resvg/resvg-js — no headless Chrome, no browser binaries. One tiny Node service, four built-in themes, the Inter typeface and 4,009 offline color-emoji assets baked in.

GET /og and POST /og → image/png (1200×630 by default, size configurable 200–4096)
Themes: dark, light, gradient, card — see the previews in the repo README
GET /themes lists built-ins; GET /health returns status, uptime and memory
Long titles wrap and clamp with an ellipsis; emoji (including ZWJ, skin-tone and flags) render offline
Cache-Control: public, max-age=86400 on every render plus an in-memory LRU cache
Remote logo URLs are disabled by default behind an SSRF-hardened fetcher
Zero environment variables required — deploy and it works

Deploy and Host

Deploying provisions a single Railway service called og-image, built from the repo's root Dockerfile (Node 22 slim, multi-stage, non-root runtime) and served on Railway's injected PORT. A public domain is attached automatically, and Railway health-checks the deployment against GET /health with an ON_FAILURE restart policy (10 retries). No environment variables and no database are needed; the first successful deployment serves /health immediately after start.

About Hosting

You host one stateless Node.js container. Because rendering happens in-process (satori builds SVG, resvg rasterizes it — no browser subprocess), a 512 MB instance stays far under budget: after 20 sequential 1200×630 renders the service idles around 90–135 MB RSS. That keeps typical hosting at roughly $5/month on Railway's smallest instance. Images are served with Cache-Control: public, max-age=86400 and an LRU cache, so repeat traffic is cheap. Optional configuration (all off/optional by default): ALLOW_REMOTE_ASSETS=true to enable remote logo URLs, CACHE_MAX_ENTRIES to tune the LRU, and a /fonts volume mount to add fallback fonts (e.g. Noto Sans for CJK).

Why Deploy

Every other OG-image route wants a browser: Puppeteer/Chrome images weigh 1 GB+ and eat 512 MB+ of RAM per render spike, and the hosted APIs are per-call billed and platform-locked. This template runs the renderer in-process with pinned native binaries (~150 MB image, tens of milliseconds per render), works from any HTTP client, and you own the whole pipeline — self-hosted, platform-neutral, MIT-licensed template code with all bundled assets properly attributed (Inter: SIL OFL 1.1; twemoji: CC-BY 4.0; satori and resvg-js: MPL-2.0 — see NOTICE.md).

Common Use Cases

Open Graph / Twitter-card images for blogs, docs sites and landing pages, generated at build time or on first share
Dynamic per-user or per-post social cards (title/subtitle/logo come from the query string or a JSON POST)
Preview thumbnails for CMS entries, e-commerce products, or link aggregators
Anywhere you need a real PNG at social-media dimensions without maintaining a browser fleet — including private/self-hosted networks, since rendering is 100% offline

Dependencies for

This template has no external dependencies: a single og-image service, no database, no workers, no required environment variables, and no outbound calls at runtime.

Deployment Dependencies

None. The container ships everything: Node 22, satori, resvg-js (prebuilt linux-x64-gnu binary), the Inter typeface, and the twemoji asset set. The only optional toggle is ALLOW_REMOTE_ASSETS (default false) if you want to pass remote logo URLs to /og; when enabled, fetches are SSRF-guarded (private/loopback/link-local/CGNAT ranges, redirects, size and content-type are all validated).