Sereinly: Building a "Nothing Persists" Product on Top of a Backend That Necessarily Persists Some Things

Sereinly positioned itself in the market by emphasizing a privacy promise: what users typed in did not get stored. Precision in this claim's architecture was required, as stating that no data is stored can be misleading if focused solely on certain system layers. Key components that do persist include account information, subscriptions, usage limits for paid SaaS functionality, and a separate usage-tracking layer for metrics like session minutes on metered plans.

The core of Sereinly's no storage claim specifically applied to message content users pasted into services like Ely, Sera, or Milo for assistance. To process this content, AI functionality was routed through server-side API routes, not client-side services, after an earlier client-side version was deprecated for security concerns.

The separation between persisting account/usage data and the AI-processing pathway was verified. While the dedicated usage tracking layer seemed scoped to metering metrics rather than content, the full request lifecycle within server-side API routes for message content verification was not directly traced. This creates a notable gap in confirming that message content is never written to logs, databases, or request logs during its server-side processing.

Precision in a privacy claim extends beyond just stating "no storage" for product data; it must account for all data layers it traverses, including logging infrastructure, error tracking tools, and third-party API providers. A comprehensive claim needs to address every potential data retention path, not just the user-facing aspect the product team emphasizes in marketing material.