Type · algorithms
Explain how you would write an algorithm to find the longest common prefix across asynchronous event stream log strings from multiple enterprise connectors to group duplicate execution triggers.
How to Pass the Delos Software Engineer Interview in 2026
Growth · Software Engineer Interview Guide
Interview language: English
The Delos DNA (TL;DR)
Integrating AI digital workers into tools like Microsoft Teams requires robust systems thinking. Evaluation focuses on how effectively applicants construct prompt workflows, instrument agent guardrails, and articulate trade-offs when deploying autonomous workforce solutions.
The Delos Interview Loop
Your onsite loop will typically consist of 4 rounds.
- 1
Round 1
Recruiter ScreenMotivation, role fit, logistics. - 2
Round 2
Coding ScreenLeetCode-medium algorithmic problems under time pressure. - 3
Round 3
System DesignDistributed systems, trade-offs at scale, architecture under constraints. - 4
Round 4
Onsite CodingLeetCode-hard problems, reasoning about defects, code clarity, edge cases.
The Danger Zone: Top Reasons Candidates Fail
Based on our database of Delos interview outcomes, avoid these common traps:
- Focusing purely on high-level AI prompt engineering rather than core software engineering infrastructure
- Using simple visited sets that fail to distinguish between nodes in the current recursion stack versus previously processed subgraphs
- Creating a background thread timer per tenant which scales poorly to thousands of active enterprise accounts
- Assuming downstream external APIs natively support idempotency headers without verifying their contracts
Test Yourself: Real Delos Questions
Three real prompts pulled from our database.
Type · data-structures
How would you implement a distributed sliding window rate limiter that shares state across worker nodes using minimal network roundtrips to enforce enterprise tier usage limits?
Type · algorithms-hard
How would you design an algorithm to compute the topological sort of a multi-tenant workflow graph with dynamic runtime conditional branches while detecting deadlock conditions?
+ many more questions, signals, and worked examples
Sign up to unlock the full Delos grading rubric
Delos Interview Question Bank
A sample from our database, grouped by round. Sign up to see the full set.
7 of 15 questions shown
1
Recruiter Screen
1- 1
Type · motivation
Why are you interested in building infrastructure for autonomous AI digital workers at Delos, and what technical challenges in B2B workflow automation excite you most?
2
Coding Screen
4- 2
Type · algorithms
How would you implement an in-memory token bucket rate limiter to control API calls made by AI agents to third-party integrations, supporting dynamic rate updates per tenant without blocking concurrent requests? - 3
Type · data-structures
How would you design an efficient data structure and algorithm to detect circular dependencies in a dynamic directed acyclic graph (DAG) representing custom user-defined execution steps? - + 2 more questions in this round (sign up to unlock)
3
System Design
5- 4
Type · system-architecture
Design an asynchronous execution engine for multi-step AI digital workers that interact with external enterprise APIs while guaranteeing at-least-once delivery, tenant isolation, and strict audit logging. - 5
Type · distributed-systems
How would you architect a real-time prompt guardrail and validation service that evaluates incoming agent inputs and outputs against security policies under 50ms latency at high throughput? - + 3 more questions in this round (sign up to unlock)
4
Onsite Coding
5- 6
Type · concurrency
Walk through how you would diagnose and resolve a race condition where two asynchronous agent threads concurrently update state in a shared workflow step, leading to duplicate webhook triggers. - 7
Type · algorithms-hard
How would you design an algorithm to compute the topological sort of a multi-tenant workflow graph with dynamic runtime conditional branches while detecting deadlock conditions? - + 3 more questions in this round (sign up to unlock)
Unlock all 15 Delos questions, free
No credit card. Every question with its framework, the grading signals interviewers score against, and a worked answer for each.
Interview tracks at Delos
How Delos's DNA translates across functions. Pick your role.
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Practice Delos interviews end-to-end
Delos Mock Interview
Run a live mock interview with our AI interviewer using Delos-style prompts. Get scored on structure, signal, and answer length - exactly how the real loop grades you.
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STAR Stories for Delos Behavioral Rounds
Build a Story Bank of your past wins, mapped to the leadership signals Delos interviewers grade on. Reuse them across every behavioral round.
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Delos Interview Prep Hub
The frameworks behind every Delos round: CIRCLES for product sense, hypothesis-driven debugging for analytical, STAR for behavioral. Learn each one in 10 minutes.
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Interview Frameworks
CIRCLES, STAR, AARRR, RICE, MECE. The exact frameworks that make Delos interviewers nod instead of frown. Step-by-step playbooks with the moves and the pitfalls.
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Sample answers
What a strong answer to these Delos interview questions shows.
Explain how you would write an algorithm to find the longest common prefix across asynchronous event stream log strings from multiple enterprise connectors to group duplicate execution triggers.
A strong answer shows: Selects optimal string comparison approach based on stream volume and average string length; Avoids redundant string copying by operating on character indices or memory pointers; Handles early termination as soon as a mismatch occurs across any stream string.
How would you implement a distributed sliding window rate limiter that shares state across worker nodes using minimal network roundtrips to enforce enterprise tier usage limits?
A strong answer shows: Executes atomic operations using Lua scripting or pipelined atomic commands; Balances rate limiting accuracy against memory consumption by cleaning up expired timestamps; Explores fallback strategies when cache store latency degrades or becomes unavailable.
Frequently asked questions
How long does the Delos interview process take?
Most candidates spend between 4 and 8 weeks from recruiter screen to offer. The onsite loop itself runs in a single day or is split across two half-days, with debrief and offer typically within 5 business days after.
How should I prepare specifically for Delos?
Focus on three things: (1) the company DNA shown above - what they actually grade for, (2) the rounds in your loop, especially the round most candidates underestimate, and (3) drilling on the question types in this guide using a structured framework like CIRCLES or STAR.
Does this apply to engineering or design roles at Delos?
The DNA stays the same - what changes is the round mix. SWE candidates face coding screens instead of Product Sense; designers face portfolio reviews and design exercises. The "what they value" and behavioral signals carry across all functions.
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