← Spotify Interview Insights

Spotify·Machine Learning Engineer·Onsite - System Design / Architecture·Senior

Senior
Jun 2026

Summary

Spotify ML engineer system design round, one big open-ended question about building a podcast recap pipeline end to end. Took the full session and then some. Pretty thorough scope, felt like they wanted to see if you'd drown or swim.

Questions Asked (1)

Q1

Design a production system that generates short podcast recaps for newly published episodes, covering ingestion, transcription, summarization, serving, and monitoring.

System DesignTechnical Trade-offsProduct Sense & Ideation
Author's notes

This thing sprawls in every direction and I did not pace myself well.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and scale (e.g., number of new episodes per day, latency targets, recap length). Then walk through the end-to-end pipeline: ingestion, transcription, summarization, serving, and monitoring, highlighting key design choices and trade-offs at each stage. Emphasize how you would evaluate and iterate on the ML components.

Pro tip: Anchor your design around the user experience: the recap should be timely, accurate, and engaging. Discuss how you'd measure success (e.g., listen-through rate, user retention) and use that to drive technical decisions like model selection and latency budgets.

1. Clarify Requirements and Scale

Ask questions to understand the volume of new episodes, desired latency (e.g., recap available within minutes or hours), recap length, and supported languages. Identify non-functional requirements like cost, scalability, and fault tolerance.

2. Design Ingestion and Transcription

Outline how new episodes are detected (e.g., via RSS feeds or a message queue) and how audio is fetched and stored. Choose a transcription approach (e.g., pre-trained ASR like Whisper, or a cloud service) and discuss handling of long audio, speaker diarization, and language detection.

3. Design Summarization and Generation

Describe the summarization pipeline: preprocess transcript (e.g., segment, clean), apply a summarization model (e.g., fine-tuned LLM or abstractive model), and post-process for coherence and length. Discuss trade-offs between extractive and abstractive methods, and how to ensure factual consistency.

4. Design Serving and Delivery

Explain how recaps are stored (e.g., in a database or object store) and served to users (e.g., via API, push notifications, or in-app). Consider caching, CDN, and personalization (e.g., different recap lengths per user).

5. Design Monitoring and Evaluation

Define monitoring for pipeline health (e.g., latency, error rates) and model performance (e.g., transcription WER, summarization ROUGE, user engagement metrics). Include A/B testing and feedback loops for continuous improvement.

Key Points to Mention

  • Trade-offs between real-time vs. batch processing for transcription and summarization
  • Choice of ASR and summarization models: open-source vs. proprietary, accuracy vs. cost
  • Handling of long audio and context window limitations in LLMs (e.g., chunking, hierarchical summarization)
  • Scalability and cost optimization: using spot instances, caching, and asynchronous processing
  • Evaluation metrics: both automated (WER, ROUGE) and human/user-centric (engagement, satisfaction)
  • Monitoring and alerting: detecting drift, failures, and ensuring timely delivery

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.