> ## Documentation Index
> Fetch the complete documentation index at: https://nenyax.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Cost Tracking

> Per-session and aggregate cost tracking across all providers.

# Cost Tracking

Nenyax tracks the cost of every API call made during voice sessions — STT minutes, LLM tokens, and TTS characters.

## How Costs Are Tracked

1. The agent worker logs usage events in real-time via `POST /api/usage/events`
2. Each event records the provider, service type, units consumed, and calculated cost
3. The backend aggregates costs for dashboards and reports

## Provider Rates

Rates are defined in `backend/app/cost_rates.py` and can be updated in one place.

| Service | Provider                | Unit                    | Rate      | Hourly Equivalent  |
| ------- | ----------------------- | ----------------------- | --------- | ------------------ |
| STT     | Deepgram                | per minute              | \$0.0077  | \$0.46/hr          |
| STT     | AssemblyAI              | per minute              | \$0.0078  | \$0.47/hr          |
| STT     | ElevenLabs              | per minute              | \$0.0167  | \$1.00/hr          |
| LLM     | Google Gemini 2.5 Flash | per 1K tokens (blended) | \$0.00086 | \~\$0.86/1M tokens |
| TTS     | Resemble AI             | per character           | \$0.00004 | \$40/1M chars      |

<Note>
  The Gemini rate is a blended estimate assuming a \~3:1 input-to-output token ratio. Actual rates: $0.30/1M input tokens, $2.50/1M output tokens.
</Note>

## Usage Event Structure

```json theme={null}
{
  "session_id": "uuid",
  "user_id": "user-id",
  "agent_id": "agent-uuid",
  "provider": "assemblyai",
  "event_type": "stt_minutes",
  "quantity": 2.5,
  "unit_cost": 0.0078,
  "total_cost": 0.0195
}
```

## Dashboard Views

### Cost Summary

**Dashboard → Costs** shows:

* Total cost across all sessions
* This month's cost
* Breakdown by provider (pie chart)

### Cost Timeline

View costs over time with daily, weekly, or monthly granularity.

### Cost by Agent

See which agents cost the most, helping you optimize prompts and configurations.

### Per-Session Breakdown

**Dashboard → Call Logs → \[Session]** shows the cost breakdown for a single call:

| Provider      | Service | Units          | Cost         |
| ------------- | ------- | -------------- | ------------ |
| AssemblyAI    | STT     | 2.5 minutes    | \$0.0195     |
| Google Gemini | LLM     | 1,250 tokens   | \$0.0011     |
| Resemble AI   | TTS     | 450 characters | \$0.0180     |
| **Total**     |         |                | **\$0.0386** |

## What's Not Tracked

Nenyax currently does **not** track costs for:

* **LiveKit** — connection minutes (\~\$0.0005/min per participant). These are billed by LiveKit directly.
* **Twilio** — per-minute telephony charges for inbound/outbound calls. These are billed by Twilio directly.

These costs are external to the voice pipeline and must be monitored in each provider's billing dashboard.

## API Endpoints

```bash theme={null}
# Cost summary
curl -H "x-user-id: your-user-id" http://localhost:8000/api/costs/summary

# Cost timeline (daily/weekly/monthly)
curl -H "x-user-id: your-user-id" "http://localhost:8000/api/costs/timeline?period=daily"

# Cost by agent
curl -H "x-user-id: your-user-id" http://localhost:8000/api/costs/by-agent
```