Scale Engineer

Principal Engineer

Software EngineerIC7Very High

This interview process is designed to assess candidates for the Principal Engineer (IC7) role at Reddit. It focuses on deep technical expertise, system design capabilities, leadership potential, and a strong understanding of large-scale distributed systems. Candidates will be evaluated on their ability to tackle complex problems, mentor junior engineers, and contribute to the strategic technical direction of the company.

Rounds·4

Timeline·~14d

Experience·8 - 15 yrs

Comp band·US$180000 - US$250000

Interview time·240 min

Evaluation

What they measure.

  • Technical depth and breadth
  • System design and architecture skills
  • Problem-solving abilities
  • Leadership and mentorship potential
  • Communication and collaboration skills
  • Understanding of scalability, reliability, and performance
  • Cultural fit and alignment with Reddit's values

Preparation

How to prepare.

Tips

  1. Deeply understand Reddit's products, services, and technical challenges.
  2. Review core computer science fundamentals, data structures, and algorithms.
  3. Practice system design problems, focusing on scalability, reliability, and trade-offs.
  4. Prepare to discuss your past projects and contributions in detail, highlighting leadership and impact.
  5. Familiarize yourself with common distributed systems concepts and patterns.
  6. Research Reddit's engineering culture and values.
  7. Prepare questions to ask the interviewers about the role, team, and company.

Study plan

Fig · Study plan — 05 phases

01 / 05
01

Phase 01 of 05

Data Structures & Algorithms

Weeks 1-2: DSA Fundamentals (LeetCode Medium/Hard).

Weeks 1-2: Focus on core data structures and algorithms. Review common algorithms (sorting, searching, graph traversal) and data structures (arrays, linked lists, trees, hash maps). Practice problems on platforms like LeetCode (Medium/Hard).

Questions

Commonly asked.

  • Design a system to handle real-time notifications for millions of users.
  • How would you scale a service that is experiencing a sudden surge in traffic?
  • Describe a time you had to lead a technical project from inception to completion.
  • What are the trade-offs between monolithic and microservices architectures?
  • How do you approach debugging a complex distributed system?
  • Tell me about a significant technical failure you were involved in and what you learned.
  • How do you stay updated with the latest technologies and trends?
  • What is your experience with performance tuning and optimization?
  • How would you design a rate limiter for an API?
  • Describe your approach to code reviews and ensuring code quality.

Locations

Regional differences.

Fig · Regions — 02 locations

01 / 02

Location

San Francisco, USA

Interview focus

Emphasis on leadership and mentorship in technical decision-making.Deeper dive into architectural patterns and their application to Reddit's specific challenges.Understanding of operational excellence and site reliability engineering principles.

Common questions

  • Discuss a time you had to influence a team with a different technical opinion.
  • How do you approach mentoring and growing junior engineers?
  • Describe a complex system you designed and the trade-offs involved.
  • What are your thoughts on the current state of distributed systems and future trends?
  • How do you handle ambiguity and drive technical decisions in a fast-paced environment?

Tips

  • Be prepared to discuss your contributions to open-source projects or significant technical publications.
  • Highlight instances where you've driven technical strategy and influenced product roadmaps.
  • Showcase your ability to communicate complex technical concepts to both technical and non-technical audiences.

Rounds

Round-by-round.

Expand a step for evaluation criteria, sample questions, and prep notes.

DSA

Coding questions at Reddit.

Frequently reported on Reddit loops

View all at Reddit

Other guides

More at Reddit.