Zoho Flow webhook trigger 100 per minute vs Sume bulk-run bursts

A Sume bulk run of up to 100 items can send its per-item completion webhooks faster than a Zoho Flow webhook trigger accepts them. Zoho's FAQ says Zoho Flow supports 300 executions per minute for an app trigger and 100 per minute for a webhook trigger. Put a small buffer in front, or use the app-trigger path, and treat Sume's retries as normal.

The numbers

Why bursts happen

A bulk run takes up to 100 items with a concurrency setting. Each item can carry its own webhook, because the queue has none, so items finishing close together send close together events. Each is format.run.terminal with status, outcome and a payload receipt. Lowering concurrency spreads completions.

Absorb, dedupe, acknowledge

Sume retries failed deliveries up to 10 times, with exponential backoff for run webhooks bounded at one hour and by any Retry-After you return. If Zoho rejects some deliveries during a burst, they will come back. Make the flow idempotent: key on run_id or request_id.

• Return a fast 2xx from a buffer, then feed Zoho at its own pace.
• Verify the HMAC sume-v1= signature in the buffer.
• Read GET /v1/format-run-queues/{id} to reconcile, since canceled and skipped runs send no webhook.

Alternative: poll the queue

If a buffer is too much, skip item webhooks and have a scheduled Zoho flow read the queue endpoint. Polling reads state directly and cannot lose events. Use one method per item to avoid double handling, and replay a missed delivery with POST /v1/format-runs/{id}/webhook/redeliver.