All posts

Developer API · June 2, 2026 · 5 min read

How to Automate Video Rendering at Scale with a Cloud API

Learn how to build automated video creation workflows, configure programmatic timeline JSON payloads, and leverage webhooks using RenderSnap's REST API.

If you are building a product that requires dynamic video generation—like automated real-estate listings, personalized e-commerce ads, programmatic podcast clips, or bulk social branding—manually clicking inside an editor doesn't scale. You need a fast, cloud-based REST API to programmatically compose timelines and trigger parallel renders.

Automate Video Rendering at Scale

Integrate RenderSnap programmatically. Compose complex JSON timelines, fetch storage-signed upload URLs, fire batch social renders, and listen for completion callbacks in real-time.

Open API SandboxREST JSON API · Parallel Render Worker Queue · HMAC Webhook Signatures

Core Developer Resources

Try it live

Interactive Sandbox

Test, execute, and verify REST API calls programmatically in real-time directly from your browser context.

Open API Playground

API Reference Docs

Browse standard JSON schemas and headers for Projects, Assets, Renders, Workspaces, and Templates.

View API Reference

Webhook Verification

Learn how the render worker secures completion callbacks using timing-safe HMAC-SHA256 signatures.

Webhook Reference

How to automate video rendering in 4 steps

Build Your Automated Video Pipeline

  1. 1. Generate an API Key

    Navigate to your developer dashboard settings, select the API Keys panel, and generate a new key scoped with read/write permissions.

  2. 2. Define a Timeline JSON

    Structure your canvas dimensions, tracks, and clips. Define image URLs, text strings, font stylings, and background audio files programmatically.

  3. 3. Submit a Render Job

    POST the timeline JSON to our Renders endpoint. The API instantly places the job on the Redis-backed BullMQ queue, returning a job ID.

  4. 4. Acknowledge Webhook Completion

    Our high-speed render worker processes the timeline in the cloud. Once finished, it hits your server webhook, providing a secure download link.

Programmatic Timelines: The Power of Track Overlay Layers

Instead of rendering inside the browser (which slows down client CPUs and drains device batteries), RenderSnap runs a high-performance rendering engine server-side. The entire video is described as a Timeline JSON payload:

  • Image Tracks — Link to background photos or product mockups directly from Unsplash or your private storage CDN. Add transition effects like zoom-in or zoom-out to make static images dynamic.
  • Text Tracks — Dynamically overlay text strings (bold headers, subtitles, or labels) with fully customizable font sizes, families, alignments, and fade-in animations.
  • Audio Tracks — Couple multiple sound files or voice narration tracks, trim audio starting points, and let our sound mixer handle overlay levels.

High-Volume Batch Renders

For social teams, RenderSnap offers a powerful Batch Social Fan-Out feature. Submit a single timeline JSON and select multiple target formats (e.g. youtube, tiktok, instagram_square):

  1. The API automatically duplicate-scales the coordinates to target vertical, landscape, or square aspects.
  2. It distributes the render tasks into separate concurrent jobs in the worker cluster.
  3. Each video renders in parallel, delivering independent, optimized output files simultaneously.

Securing Webhooks with HMAC

When the cloud render worker finishes creating your video, it alerts your API server by POSTing a JSON payload. To prevent bad actors from spoofing completions, all webhook calls are cryptographically signed with a secure, server-level RENDER_WORKER_SECRET using a timing-safe HMAC-SHA256 checksum.

Your endpoint should verify this signature before updating the project state or notifying the user:

const crypto = require("crypto");

function verifySignature(rawBody, signature, secret) {
  const expected = crypto
    .createHmac("sha256", secret)
    .update(rawBody)
    .digest("hex");
  
  const actual = Buffer.from(signature.replace(/^sha256=/, ""), "hex");
  const exp = Buffer.from(expected, "hex");
  
  if (actual.length !== exp.length) return false;
  return crypto.timingSafeEqual(actual, exp);
}

Related guides