10 Datadog Software Engineer (New Grad) Interview Questions (2026)
Datadog's new-grad SWE loop in 2026 is a recruiter screen, one OA on HackerRank, one phone screen, and a four-round virtual onsite. The bar is heavy on practical engineering — clean code, complexity reasoning, and at least one round on systems concepts (networking, observability, distributed systems basics). Expect a take-home option for some teams.
By Sam K., Founder, InterviewChamp.AI · Last verified
What is the Datadog Software Engineer (New Grad) interview process?
New-grad timeline reports run 4-6 weeks in 2026. Flow: recruiter → OA (HackerRank, 60-90 min, 2-3 problems) → 45-min phone screen → four 45-60 minute onsite rounds. Onsite is typically two coding (medium-hard), one systems/networking concepts, and one behavioral. Some teams replace one coding round with a structured take-home worth ~3 hours.
Behavioral (3)
Tell me about a time you debugged a production-like issue. What was your process?
Frequently askedOutline
STAR. Datadog literally builds monitoring tools — they value engineers who think in terms of metrics, logs, traces. Show structured isolation: reproduce, narrow down via observable signals, hypothesize, verify. Quantify the impact and time-to-resolution. Generic 'I added print statements' answers underperform.
Why Datadog? What interests you about observability or monitoring?
Frequently askedOutline
Concrete reference works best. Mention a class or project where you wrote logs, used a debugger, or instrumented something. Tie it to the broader idea of making complex systems understandable. Generic 'cloud monitoring is hot' answers underperform; Datadog interviewers spot rehearsed enthusiasm.
Tell me about a time you had to disagree with a teammate. How did you handle it?
Occasionally askedOutline
STAR. Pick a real instance where you took a principled stand on a technical or process question. Show you listened first, brought data, escalated only when needed. End with what you learned from the disagreement, not just the outcome.
Coding (LeetCode patterns) (4)
Implement a function that computes the moving average of a stream of integers over the last N values.
Frequently askedOutline
Circular buffer of size N plus a running sum. On each add: subtract the value being evicted (if buffer is full), add the new value, append to buffer. Average is sum / current_size. O(1) per add, O(N) space. Walk through the eviction logic — wrap-around indexing trips people up.
Given a list of intervals representing busy times, return a list of free intervals between them.
Frequently askedOutline
Sort intervals by start. Walk through; for each interval, if there is a gap between previous_end and current_start, emit (previous_end, current_start). Update previous_end = max(previous_end, current_end) to handle overlap. O(n log n). Edge cases: overlapping busy intervals, intervals touching exactly.
Implement a function that returns the top K most frequent strings in a list.
Frequently askedOutline
Count frequencies in a hash map, then min-heap of size k keyed by frequency. O(n log k) time, O(n) space. Alternative: bucket sort by frequency for O(n). For tiebreaking by lexicographic order, customize the comparator. Discuss with interviewer.
Given a binary tree, return the maximum depth.
Occasionally askedOutline
Recurse: if node is null return 0; else return 1 + max(depth(left), depth(right)). O(n) time, O(h) space. Iterative alternative with BFS, tracking level count. Pick one and explain.
Technical (3)
Given a list of log entries with timestamps, find all the unique IP addresses that hit the API in the last hour.
Frequently askedOutline
Walk through: iterate entries newest-to-oldest, stop when timestamp is older than now-3600. Collect IPs into a hash set. Return as list. O(n) in worst case. Discuss: if log is sorted, you could binary-search the cutoff. If log is a stream, you would use a sliding window with a deque keyed by timestamp.
Explain what happens when you type a URL into a browser and hit enter.
Frequently askedOutline
Classic question — answer thoroughly: DNS lookup (recursive resolver, root → TLD → authoritative), TCP handshake, TLS handshake, HTTP request, server processing, response, browser parsing (HTML → DOM, CSS → CSSOM, JS execution), render. Datadog cares about depth on observability-adjacent layers: DNS, networking, server-side latency contributors.
Design a simple metrics aggregation system that ingests counter increments and returns rates over time windows.
Occasionally askedOutline
Per-metric: ring buffer of (timestamp, value) tuples bucketed by second/minute. On ingestion: add to current bucket. On query: walk buckets in the window, sum/average. Discuss retention policy (drop old buckets), concurrency (lock per metric), and aggregation across machines (some form of shuffle by metric name). Lightweight design discussion — new-grads not expected to design full distributed systems.
Datadog interview tips
- Systems-thinking matters at Datadog. Be able to talk about HTTP, DNS, TCP, networking basics, and how applications generate observable signals (metrics, logs, traces).
- Have one project you can talk about where you instrumented or debugged something — added logging, used a profiler, wrote a small monitoring script. Datadog interviewers love these stories.
- Coding rounds favor candidates who explain their reasoning out loud. Walk through complexity before coding, name your variables clearly, handle edge cases explicitly.
- Behavioral rounds probe collaboration. Datadog values low-ego engineers — avoid stories where you were the only one who could fix something.
- The take-home (if you get one) is graded on code quality as much as correctness. Submit working code with clear README, tests, and a brief design note. Do not over-engineer.
Frequently asked questions
What questions does Datadog ask in the Software Engineer (New Grad) interview?
This page collects 10 Datadog Software Engineer (New Grad) interview questions: 3 technical, 4 coding (LeetCode patterns) and 3 behavioral. The ones candidates report most often: "Given a list of log entries with timestamps, find all the unique IP addresses that hit the API in the last hour.", "Implement a function that computes the moving average of a stream of integers over the last N values." and "Explain what happens when you type a URL into a browser and hit enter.". Each has an answer outline above.
How long is Datadog's SWE new-grad interview process in 2026?
Most reports show 4-6 weeks from OA to offer. Referrals can compress to 3 weeks.
Does Datadog give a take-home assignment?
Some teams do, especially for backend and infrastructure roles. The take-home is typically a 3-hour build-and-test exercise. If offered, you can usually opt for an additional virtual round instead.
Does Datadog ask system design for new-grad SWE?
A lightweight design discussion is common. Topics are usually observability-adjacent: rate counters, metric aggregation, simple monitoring agents. New-grads are not expected to deliver senior-level designs.
What programming languages does Datadog use?
Go is heavy in the agent and backend infrastructure. Python is common for tooling and ML. The interview accepts any language; production stack knowledge is not required at the new-grad level.
Does Datadog have offices outside New York?
Yes — Boston, Seattle, Paris, Dublin, Tokyo, and a handful of other locations. Confirm with your recruiter; some teams are office-specific and remote availability varies by role.
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