PostHog Data Handling

Overview

Handle sensitive data correctly when integrating with PostHog.

Prerequisites

Understanding of GDPR/CCPA requirements
PostHog SDK with data export capabilities
Database for audit logging
Scheduled job infrastructure for cleanup

Data Classification

Category	Examples	Handling
PII	Email, name, phone	Encrypt, minimize
Sensitive	API keys, tokens	Never log, rotate
Business	Usage metrics	Aggregate when possible
Public	Product names	Standard handling

PII Detection

const PII_PATTERNS = [
  { type: 'email', regex: /[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}/g },
  { type: 'phone', regex: /\b\d{3}[-.]?\d{3}[-.]?\d{4}\b/g },
  { type: 'ssn', regex: /\b\d{3}-\d{2}-\d{4}\b/g },
  { type: 'credit_card', regex: /\b\d{4}[- ]?\d{4}[- ]?\d{4}[- ]?\d{4}\b/g },
];

function detectPII(text: string): { type: string; match: string }[] {
  const findings: { type: string; match: string }[] = [];

  for (const pattern of PII_PATTERNS) {
    const matches = text.matchAll(pattern.regex);
    for (const match of matches) {
      findings.push({ type: pattern.type, match: match[0] });
    }
  }

  return findings;
}

Data Redaction

function redactPII(data: Record<string, any>): Record<string, any> {
  const sensitiveFields = ['email', 'phone', 'ssn', 'password', 'apiKey'];
  const redacted = { ...data };

  for (const field of sensitiveFields) {
    if (redacted[field]) {
      redacted[field] = '[REDACTED]';
    }
  }

  return redacted;
}

// Use in logging
console.log('PostHog request:', redactPII(requestData));

Data Retention Policy

Retention Periods

Data Type	Retention	Reason
API logs	30 days	Debugging
Error logs	90 days	Root cause analysis
Audit logs	7 years	Compliance
PII	Until deletion request	GDPR/CCPA

Automatic Cleanup

async function cleanupPostHogData(retentionDays: number): Promise<void> {
  const cutoff = new Date();
  cutoff.setDate(cutoff.getDate() - retentionDays);

  await db.posthogLogs.deleteMany({
    createdAt: { $lt: cutoff },
    type: { $nin: ['audit', 'compliance'] },
  });
}

// Schedule daily cleanup
cron.schedule('0 3 * * *', () => cleanupPostHogData(30));

GDPR/CCPA Compliance

Data Subject Access Request (DSAR)

async function exportUserData(userId: string): Promise<DataExport> {
  const posthogData = await posthogClient.getUserData(userId);

  return {
    source: 'PostHog',
    exportedAt: new Date().toISOString(),
    data: {
      profile: posthogData.profile,
      activities: posthogData.activities,
      // Include all user-related data
    },
  };
}

Right to Deletion

async function deleteUserData(userId: string): Promise<DeletionResult> {
  // 1. Delete from PostHog
  await posthogClient.deleteUser(userId);

  // 2. Delete local copies
  await db.posthogUserCache.deleteMany({ userId });

  // 3. Audit log (required to keep)
  await auditLog.record({
    action: 'GDPR_DELETION',
    userId,
    service: 'posthog',
    timestamp: new Date(),
  });

  return { success: true, deletedAt: new Date() };
}

Data Minimization

// Only request needed fields
const user = await posthogClient.getUser(userId, {
  fields: ['id', 'name'], // Not email, phone, address
});

// Don't store unnecessary data
const cacheData = {
  id: user.id,
  name: user.name,
  // Omit sensitive fields
};

Instructions

Step 1: Classify Data

Categorize all PostHog data by sensitivity level.

Step 2: Implement PII Detection

Add regex patterns to detect sensitive data in logs.

Step 3: Configure Redaction

Apply redaction to sensitive fields before logging.

Step 4: Set Up Retention

Configure automatic cleanup with appropriate retention periods.

Output

Data classification documented
PII detection implemented
Redaction in logging active
Retention policy enforced

Error Handling

Issue	Cause	Solution
PII in logs	Missing redaction	Wrap logging with redact
Deletion failed	Data locked	Check dependencies
Export incomplete	Timeout	Increase batch size
Audit gap	Missing entries	Review log pipeline

Examples

Quick PII Scan

const findings = detectPII(JSON.stringify(userData));
if (findings.length > 0) {
  console.warn(`PII detected: ${findings.map(f => f.type).join(', ')}`);
}

Redact Before Logging

const safeData = redactPII(apiResponse);
logger.info('PostHog response:', safeData);

GDPR Data Export

const userExport = await exportUserData('user-123');
await sendToUser(userExport);

Resources

Next Steps

For enterprise access control, see posthog-enterprise-rbac.

posthog-data-handling