Fathom Cost Tuning

Overview

Optimize Fathom costs through smart tier selection, sampling, and usage monitoring.

Prerequisites

• Access to Fathom billing dashboard
• Understanding of current usage patterns
• Database for usage tracking (optional)
• Alerting system configured (optional)

Pricing Tiers

Cost Estimation

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

function estimateFathomCost(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

class FathomUsageMonitor {
  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 Fathom budget limit');
    }
  }

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

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

Cost Reduction Strategies

Step 1: Request Sampling

function shouldSample(samplingRate = 0.1): boolean {
  return Math.random() < samplingRate;
}

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

Step 2: Batching Requests

// Instead of N individual calls
await Promise.all(ids.map(id => fathomClient.get(id)));

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

Step 3: Caching (from P16)

• Cache frequently accessed data
• Use cache invalidation webhooks
• Set appropriate TTLs

Step 4: Compression

const client = new FathomClient({
  compression: true, // Enable gzip
});

Budget Alerts

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

Cost Dashboard Query

-- 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 fathom_api_logs
WHERE created_at >= NOW() - INTERVAL '30 days'
GROUP BY 1
ORDER BY 1;

Instructions

Step 1: Analyze Current Usage

Review Fathom 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

Examples

Quick Cost Check

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

Resources

• Fathom Pricing
• Fathom Billing Dashboard

Next Steps

For architecture patterns, see fathom-reference-architecture.