Estimate infrastructure or operational capacity needed for Playlists

Problem Statement Description

Product context: Spotify is an audio streaming company; its products include music, podcasts, audiobooks, playlists, recommendations, creator tools, subscriptions, and ads.

Spotify wants to understand the infrastructure and operational capacity required to support Playlists for premium subscribers. In this guesstimate, you should size the demand generated by playlist-related activity, such as playlist creation, editing, saving, following, sharing, loading, and playback initiation.

Focus on defining the scope clearly: whether you are estimating storage, API request volume, database reads/writes, cache capacity, compute load, moderation/ops effort, or another capacity dimension. The estimate should reflect Spotify’s global scale, premium subscriber behavior, and the fact that playlists are central to personalization, retention, and music discovery.

You are not expected to know Spotify’s actual internal numbers. The interviewer is looking for a structured sizing approach, reasonable assumptions, clear math, and an ability to test whether the estimate is directionally plausible.

The experience should consider:

- The unit being estimated, such as daily playlist API calls, storage required for playlist metadata, peak request capacity, or operational workload

- The relevant population, especially premium subscribers and active playlist users within that segment

- Playlist ownership and usage behavior, including number of playlists per user, tracks per playlist, edits per month, and playlist opens per day

- Frequency differences across user cohorts, such as casual listeners, heavy playlist curators, shared playlist users, and algorithmic playlist consumers

- Infrastructure implications of reads versus writes, peak-hour traffic, caching, replication, and global availability

- Assumptions around metadata size, event logging, recommendations, search, and synchronization across devices

- Sensitivity of the estimate to the largest assumptions, such as active user share, average playlists per user, and peak-to-average traffic ratio

- Sanity checks against comparable consumer-scale audio, social, or content library products

The goal is to produce a clear, defensible capacity estimate that could help a Spotify product or infrastructure team reason about scale, prioritize system investments, and identify which assumptions would need validation before making a real planning decision.