posthog-cost-tuning by jeremylongshore

---
name: posthog-cost-tuning
description: |
  Optimize PostHog costs through tier selection, sampling, and usage monitoring.
  Use when analyzing PostHog billing, reducing API costs,
  or implementing usage monitoring and budget alerts.
  Trigger with phrases like "posthog cost", "posthog billing",
  "reduce posthog costs", "posthog pricing", "posthog expensive", "posthog budget".
allowed-tools: Read, Grep
version: 1.0.0
license: MIT
author: Jeremy Longshore <[email protected]>
---

# PostHog Cost Tuning

## Overview
Optimize PostHog costs through smart tier selection, sampling, and usage monitoring.

## Prerequisites
- Access to PostHog billing dashboard
- Understanding of current usage patterns
- Database for usage tracking (optional)
- Alerting system configured (optional)

## Pricing Tiers

| Tier | Monthly Cost | Included | Overage |
|------|-------------|----------|---------|
| Free | $0 | 1,000 requests | N/A |
| Pro | $99 | 100,000 requests | $0.001/request |
| Enterprise | Custom | Unlimited | Volume discounts |

## Cost Estimation

```typescript
interface UsageEstimate {
  requestsPerMonth: number;
  tier: string;
  estimatedCost: number;
  recommendation?: string;
}

function estimatePostHogCost(requestsPerMonth: number): UsageEstimate {
  if (requestsPerMonth <= 1000) {
    return { requestsPerMonth, tier: 'Free', estimatedCost: 0 };
  }

  if (requestsPerMonth <= 100000) {
    return { requestsPerMonth, tier: 'Pro', estimatedCost: 99 };
  }

  const proOverage = (requestsPerMonth - 100000) * 0.001;
  const proCost = 99 + proOverage;

  return {
    requestsPerMonth,
    tier: 'Pro (with overage)',
    estimatedCost: proCost,
    recommendation: proCost > 500
      ? 'Consider Enterprise tier for volume discounts'
      : undefined,
  };
}
```

## Usage Monitoring

```typescript
class PostHogUsageMonitor {
  private requestCount = 0;
  private bytesTransferred = 0;
  private alertThreshold: number;

  constructor(monthlyBudget: number) {
    this.alertThreshold = monthlyBudget * 0.8; // 80% warning
  }

  track(request: { bytes: number }) {
    this.requestCount++;
    this.bytesTransferred += request.bytes;

    if (this.estimatedCost() > this.alertThreshold) {
      this.sendAlert('Approaching PostHog budget limit');
    }
  }

  estimatedCost(): number {
    return estimatePostHogCost(this.requestCount).estimatedCost;
  }

  private sendAlert(message: string) {
    // Send to Slack, email, PagerDuty, etc.
  }
}
```

## Cost Reduction Strategies

### Step 1: Request Sampling
```typescript
function shouldSample(samplingRate = 0.1): boolean {
  return Math.random() < samplingRate;
}

// Use for non-critical telemetry
if (shouldSample(0.1)) { // 10% sample
  await posthogClient.trackEvent(event);
}
```

### Step 2: Batching Requests
```typescript
// Instead of N individual calls
await Promise.all(ids.map(id => posthogClient.get(id)));

// Use batch endpoint (1 call)
await posthogClient.batchGet(ids);
```

### Step 3: Caching (from P16)
- Cache frequently accessed data
- Use cache invalidation webhooks
- Set appropriate TTLs

### Step 4: Compression
```typescript
const client = new PostHogClient({
  compression: true, // Enable gzip
});
```

## Budget Alerts

```bash
# Set up billing alerts in PostHog dashboard
# Or use API if available:
# Check PostHog documentation for billing APIs
```

## Cost Dashboard Query

```sql
-- If tracking usage in your database
SELECT
  DATE_TRUNC('day', created_at) as date,
  COUNT(*) as requests,
  SUM(response_bytes) as bytes,
  COUNT(*) * 0.001 as estimated_cost
FROM posthog_api_logs
WHERE created_at >= NOW() - INTERVAL '30 days'
GROUP BY 1
ORDER BY 1;
```

## Instructions

### Step 1: Analyze Current Usage
Review PostHog dashboard for usage patterns and costs.

### Step 2: Select Optimal Tier
Use the cost estimation function to find the right tier.

### Step 3: Implement Monitoring
Add usage tracking to catch budget overruns early.

### Step 4: Apply Optimizations
Enable batching, caching, and sampling where appropriate.

## Output
- Optimized tier selection
- Usage monitoring implemented
- Budget alerts configured
- Cost reduction strategies applied

## Error Handling
| Issue | Cause | Solution |
|-------|-------|----------|
| Unexpected charges | Untracked usage | Implement monitoring |
| Overage fees | Wrong tier | Upgrade tier |
| Budget exceeded | No alerts | Set up alerts |
| Inefficient usage | No batching | Enable batch requests |

## Examples

### Quick Cost Check
```typescript
// Estimate monthly cost for your usage
const estimate = estimatePostHogCost(yourMonthlyRequests);
console.log(`Tier: ${estimate.tier}, Cost: $${estimate.estimatedCost}`);
if (estimate.recommendation) {
  console.log(`💡 ${estimate.recommendation}`);
}
```

## Resources
- [PostHog Pricing](https://posthog.com/pricing)
- [PostHog Billing Dashboard](https://dashboard.posthog.com/billing)

## Next Steps
For architecture patterns, see `posthog-reference-architecture`.