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Decagon·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Decagon software engineer interview that basically boils down to one big question: pick a project and be ready to defend every technical decision you made. They go deep, so if you exaggerate anything on your resume you will feel it.

Questions Asked (1)

Q1

Pick a project from your background and walk through it completely: why it existed, what you personally built, the technical decisions and trade-offs you made, the hardest problem you hit and how you solved it, what failed or had to be redone, the measurable impact, and what you'd change looking back.

Technical Trade-offsSystem DesignAdaptability & Ambiguity
Author's notes

This is the whole interview basically.

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AI HintsAI Generated

Suggested Approach

Choose a project where you had significant ownership and can clearly articulate the problem, your specific contributions, and the outcomes. Structure your answer as a narrative that highlights technical depth, decision-making, and learning, while keeping it concise and focused on the most impactful aspects.

Pro tip: Quantify impact with metrics (e.g., performance improvements, cost savings, user growth) and be honest about failures—interviewers value self-awareness and the ability to learn from mistakes more than a flawless story.

1. Set the Context

Briefly explain why the project existed: the business problem, user need, or technical challenge it addressed, and your role in it.

2. Describe Your Contributions

Detail what you personally built or led, focusing on your specific actions and technical work, not just the team's efforts.

3. Explain Technical Decisions & Trade-offs

Walk through key technical choices you made, the alternatives considered, and why you chose one over another, including any trade-offs.

4. Discuss Challenges & Failures

Describe the hardest problem you encountered, how you solved it, and any failures or rework, emphasizing what you learned and how you adapted.

5. Share Impact & Reflections

Quantify the measurable impact (e.g., metrics, user feedback) and reflect on what you would do differently, showing growth and hindsight.

Key Points to Mention

  • Clear problem statement and project goals
  • Your specific role and contributions (use 'I' not 'we')
  • Technical decisions with rationale and trade-offs (e.g., scalability vs. simplicity)
  • Hardest problem, debugging approach, and solution
  • Failures or rework, and how you handled them
  • Measurable impact (metrics, business outcomes) and lessons learned

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