LIFESTYLE APPS (Uber, Starbucks, Spotify)
This NFR ensures Uber can handle 50,000 simultaneous ride requests on New Year's Eve without crashing.
What is Scalability? (Horizontal scaling with microservices allows Uber to spin up instances dynamically)
Instagram processes 95 million photos/day, requiring each upload to complete in under 2 seconds.
What is Performance? (They use CDNs and progressive image loading - notice how images sharpen?)
Apple Health can exchange data with Fitbit, Epic MyChart, and 100+ other health systems using HL7 FHIR standards.
What is Interoperability? (FHIR = Fast Healthcare Interoperability Resources - the REST API for healthcare)
Zoom's "Join meeting in 3 clicks" principle, tested to work for users aged 8 to 80.
What is Usability? (Following Nielsen's heuristic: "Recognition rather than recall")
Netflix remembers exactly where you paused "Stranger Things" across all devices.
What is Availability? (Stateful services with eventual consistency across regions)
Starbucks' app supports 31 languages and adapts currency, date formats, and even menu items by region.
What is Localization? (Goes beyond translation - "Venti" means different sizes in different countries!)
Tinder's "swipe" gesture works identically on iOS, Android, and web browsers.
What is Platform Compatibility? (React Native helps achieve "write once, deploy everywhere")
Strava must protect users' running routes from revealing home addresses or military base locations.
What is Security? (In 2018, Strava's heatmap accidentally revealed secret military bases!)
Notion automatically saves every keystroke within 500ms to prevent data loss.
What is Performance? (Conflict-free replicated data types (CRDTs) enable real-time collaboration)
Tesla's autopilot decisions must be traceable for accident investigations.
What is Explainability? ("Black box" recording + decision audit trails required by NHTSA)
Spotify must maintain 99.95% uptime, allowing only 4.38 hours of downtime per year.
What is Availability? (They use chaos engineering and redundant data centers globally)
LinkedIn logs every profile view, message, and click for compliance and user analytics.
What is Auditing? (GDPR requires ability to show users all data collected about them)
Meditation app Headspace maintains separate infrastructure to ensure HIPAA compliance for therapy features.
What is Platform Compatibility? (Different features require different compliance frameworks)
Slack Enterprise Grid tracks all messages, edits, and deletions for legal discovery requirements.
What is Auditing? (E-discovery compliance for financial services requires 7-year retention)
GitHub Copilot adapts suggestions based on your coding style, language preferences, and regional conventions.
What is Localization? (Beyond language - it learns tabs vs spaces, camelCase vs snake_case)
Uber's surge pricing algorithm must provide clear reasoning why your ride costs 3x normal, as required by EU regulations.
What is Explainability? (Algorithmic transparency laws require "glass box" not "black box" ML models)
Dating apps must implement "Privacy by Design" - collecting minimum data necessary and getting explicit consent for each use.
What is Privacy? (Bumble was fined €30M for violating GDPR's purpose limitation principle)
MyFitnessPal's 150 million users generate 50TB of daily data, requiring strategic decisions about hot/warm/cold storage tiers.
What is Sustainability? (Environmental and economic - cold storage uses 80% less energy)
Microsoft Teams must run on Windows 7, macOS 10.10, Ubuntu 16.04, and in browsers while maintaining feature parity.
What is Platform Compatibility? (Electron framework helps but creates 300MB+ apps)
Amazon's recommendation engine must balance personalization accuracy with avoiding "filter bubbles" that violate EU's Digital Services Act.
What are Performance and Privacy? (The "right to explanation" vs. proprietary algorithms)
This NFR trio creates tension when Spotify uses aggressive caching (improves X) but risks showing outdated playlists (hurts Y) while consuming more battery (impacts Z).
What are Performance, Availability, and Sustainability? (Classic NFR trade-off triangle - faster isn't always better!)
Instagram's ML-based content moderation must balance removing harmful content (X) while not censoring legitimate posts (Y), while being transparent about decisions (Z).
What are Security, Usability, and Explainability? (The "Facebook Papers" revealed this NFR tension)
Peloton's live classes require sub-100ms latency (X), 99.99% uptime during peak hours (Y), while supporting sudden 10x traffic spikes when celebrities join (Z).
What are Performance, Availability, and Scalability? (They use edge computing and predictive scaling)
Zoom's end-to-end encryption must balance security (preventing eavesdropping), performance (low latency), and explainability (showing users their data is protected).
What are Security, Performance, and Explainability? (The "Zoom bombing" crisis of 2020 exposed these tensions)
ChatGPT must maintain response times under 2 seconds (W), explain its reasoning when asked (X), prevent jailbreaking attempts (Y), while minimizing energy consumption per query (Z).
What are Performance, Explainability, Security, and Sustainability? (OpenAI reports each query uses energy equivalent to charging a phone)