Every video processing API is async. Transcription takes seconds to minutes. Clip generation runs minutes. Multi-format rendering can take longer still. That means your integration code has to decide: poll the API for status, or subscribe to webhooks for completion events. The choice has real implications for latency, infrastructure cost, and reliability.

This guide is a developer-focused look at when each pattern fits, common implementation pitfalls, and how the OpusClip API will support both. The OpusClip API is currently in early access — request access at opus.pro/api.

Key takeaways

• Webhooks are the right default for production at scale: lower latency, no wasted requests, easier multi-tenant.

• Polling is the right default for development, low-volume use, and stateless serverless workflows.

• Hybrid (webhooks + polling fallback) is the most reliable pattern for mission-critical pipelines.

• Webhook verification (HMAC signature) is non-negotiable — never trust an unverified webhook.

• Webhook receivers must be idempotent because deliveries can repeat under retry scenarios.

Why async is the only viable pattern

Video processing jobs commonly run 30 seconds to 30 minutes. Synchronous HTTP can't hold a connection that long:

• Most load balancers timeout at 30-60 seconds

• Most CDN edges timeout faster

• Browser fetch APIs typically timeout at 60-120 seconds

That leaves two options for receiving the result: poll for status, or have the API send a notification when done.

Polling: pros and cons

Pros: - Simple to implement (just a loop with a sleep) - Stateless — works in any environment without exposing an inbound endpoint - Easy to test locally - Works in serverless contexts that can't receive inbound webhooks (like browser-side code)

Cons: - Latency between job completion and detection (limited by poll interval) - Wasted requests during processing (most polls return "still working") - Cost grows linearly with concurrent jobs - Harder to scale to high concurrency (each job needs a polling worker)

When to use: - Development and testing - Low-volume production (less than ~10 concurrent jobs) - Browser-side workflows - Serverless functions without inbound webhook endpoints

Webhooks: pros and cons

Pros: - Near-real-time notification of completion - No wasted requests - Scales easily to thousands of concurrent jobs - One persistent webhook endpoint handles all jobs

Cons: - Requires a publicly reachable HTTP endpoint - Setup is more involved (signature verification, idempotency, retry handling) - Local development needs a tunnel (ngrok, localtunnel, Cloudflare Tunnel) - Lost webhook events need a recovery path

When to use: - Production at any meaningful scale - Pipelines processing hundreds or thousands of videos per day - Anything where job-completion latency matters

Webhook implementation checklist

1. Verify the signature. Every webhook should be HMAC-signed. Compute the HMAC of the request body with your webhook secret and compare to the signature header using a constant-time comparison. Never trust an unverified webhook.

2. Return 200 quickly. Webhook senders retry on non-2xx responses or timeouts. Your handler should accept the payload, queue it for processing, and return 200 within a few seconds. Don't do the actual work inside the webhook handler.

3. Be idempotent. Webhook delivery is at-least-once. The same event may arrive multiple times. Store a processed-event log and skip duplicates.

4. Handle out-of-order delivery. Webhooks can arrive out of order, especially under retry scenarios. Don't assume the "completed" event arrives before the "started" event.

5. Plan for failure. A receiver that's down for 10 minutes shouldn't lose jobs. Most APIs retry with exponential backoff over hours. Build alerting on persistent webhook failures.

Hybrid: the most reliable pattern

For mission-critical pipelines, run webhooks AND polling:

• Subscribe to webhooks for normal-case completion (fast, cheap, scales).

• Run a background job every 5-15 minutes that polls for jobs older than (poll-interval + safety margin) that haven't sent a webhook.

• For any job older than the webhook timeout that hasn't been seen, treat it as missed and reconcile.

This catches the rare webhook delivery failure without paying polling cost on the typical case. The combined pattern is what most large-scale video pipelines run.

Common pitfalls

• Trusting webhook payloads without signature verification. Anyone can call your webhook endpoint with a malicious payload. Always verify.

• Synchronous work in the webhook handler. Long-running work inside the handler causes timeouts and retries. Always queue and return.

• Forgetting idempotency. Duplicate-event handling produces double-publishes, duplicate billing events, or corrupted state.

• No retry budget. If your webhook handler is down for a few minutes, the API retries. If it's down for hours and the API gives up, you lose those events. Build alerting on webhook-handler health.

• Polling too aggressively. Polling every second is wasteful and may hit rate limits. Default to 5-10 second intervals for fast-feedback dev work, 30-60 seconds for steady-state.

How the OpusClip API will support both patterns

The OpusClip API is currently in early access. Both async patterns are first-class:

• Polling: the standard GET /jobs/{id} endpoint returns status, progress percentage, and final output URL when complete

• Webhooks: configure a webhook URL per account or per submission, get notified on job lifecycle events (started, progress, completed, failed)

• HMAC SHA-256 signature on every webhook for verification

• Configurable retry policy (default: exponential backoff up to 24 hours)

• Optional polling-fallback support for hybrid setups

Full code examples and parameter reference will publish to the developer docs when the v1 spec is finalized. To get notified or apply for early access, visit opus.pro/api.

FAQ

Which is better, webhooks or polling?

Webhooks for production at scale; polling for dev, low-volume use, and stateless serverless. Most production teams run both — webhooks as the default, polling as a fallback for missed deliveries.

How do I verify a webhook came from a real video API?

Every webhook from a reputable API includes a signature header — typically an HMAC SHA-256 of the request body computed with your webhook secret. Compare it with constant-time comparison. Never use string equality on signatures.

What happens if my webhook endpoint is down?

Most APIs retry with exponential backoff over hours or days. The OpusClip API will retry up to 24 hours with 7+ attempts. Build alerting so you know when your handler has been down long enough to risk losing events.

Can I do hybrid (webhooks with polling fallback)?

Yes, and it's the recommended pattern for mission-critical workflows. Subscribe to webhooks for normal cases; run a periodic poll to catch any jobs older than the expected webhook arrival window that haven't been processed yet.

Will the OpusClip API support both?

Yes. Webhooks for the production path, polling for dev and fallback. Both come standard from day one of the v1 GA release.

Next steps

For end-to-end pipelines that combine these patterns, see Build a YouTube-to-TikTok Automation, Convert Zoom Recordings to Social Clips, and Process Many Videos in Parallel.

Request access to the OpusClip API at opus.pro/api.