OpenRouter LLM Cost Digest: n8n to Google Sheets + Gmail

OpenRouter LLM Cost Digest for n8n: OTLP → Google Sheets + Daily Gmail Spend Report

Turn OpenRouter Observability (Broadcast) telemetry into instant cost visibility: this n8n workflow captures every LLM call from OTLP spans, logs model/token/cost/latency to Google Sheets, then emails you a daily 24-hour spend digest via Gmail—complete with the most expensive calls.

What this workflow does

• Receives OpenRouter Observability (Broadcast) OTLP spans via a webhook endpoint.
• Extracts and normalizes each span into a single LLM call record, capturing timestamp, model, provider, token usage, cost, latency, finish reason, API key name, and user.
• Immediately acknowledges the webhook with a JSON response: {ok:true}.
• Appends every call to Google Sheets in the Calls tab as a new row.
• Sends a daily digest by running every morning, reading the full call log from the same Sheets tab.
• Aggregates the last 24 hours to compute totals and breakdowns by model, then generates an HTML email highlighting the most expensive calls.
• Emails the report through Gmail to your configured recipient (optionally including a configurable number of “top expensive calls”).

Use cases

• SaaS cost monitoring: track OpenRouter LLM spend by model and identify outlier requests.
• Automation engineers: maintain a transparent audit trail of LLM calls for debugging and optimization.
• FinOps-lite teams: get a simple daily 24-hour cost digest without building custom reporting pipelines.

Technical details

• Integrations/nodes: webhook, code, google sheets, gmail, plus set and sticky note.
• Data flow: OTLP JSON spans (OpenRouter Broadcast) → parse/normalize → append rows to Google Sheets (Calls tab) → aggregate last 24 hours → HTML email via Gmail.

Setup (high level)

Create a Google Sheet with the expected Calls tab headers, connect Google Sheets OAuth, connect Gmail OAuth and set the recipient, activate the workflow, then copy your production webhook URL into OpenRouter Observability (Broadcast).