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Updated weekly · Last refresh Aug 30

Grail Software Engineer Interview Questions

The questions to prepare for a Grail Software Engineer interview. Questions from real interview reports rank first. Updated weekly.

40questions
~7htotal time
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1
CodingStart here. 13 questions · ~139 min
Longest Common SubstringHard
Practice

Find the longest contiguous substring shared by two strings using dynamic programming.

Dynamic ProgrammingArraysStringsGrail
Reverse a String in PythonEasy
Practice

Reverse a string in Python using character traversal and return the reversed result.

StringsfunctionspythonGrail
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2
Execution5 questions · ~53 min
Prioritize Features for New LaunchMedium

Explain how you would prioritize launch features when stakeholders want different things and the first release needs clear success criteria.

Trade-offsFeature PrioritizationRoadmappingGrail
Scalable Notification SystemMedium

Tests your system design skills for scalability, reliability, and delivery guarantees.

Launch PlanningTrade-offsRoadmappingGrail
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3
System Design3 questions · ~32 min
Offline and Online ML EvaluationHard

Tests ability to design rigorous evaluation pipelines and online experimentation.

Feature StoreModel ServingRecommendation SystemsGrail
Cold Start and Feature DriftHard

Tests production ML robustness, monitoring, and mitigation strategies.

Cold StartFeature DriftModel ServingGrail
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4
Behavioral & Leadership17 questions · ~181 min
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5
More topics2 questions · ~21 min
SQL Duplicate Records QueryEasy
Practice

Use GROUP BY and HAVING to identify duplicated Grail assay sample identifiers and their record counts.

Group ByHavingAggregationsGrail
Build Patient CRUD MicroserviceHard

Tests your ability to design and implement a production-ready microservice for patient data at Grail.

microservicesGrail

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Hands-on SQL practiceWrite and run real queries in the editor. 2 drills · ~20 min
Sum From 1 to 1,000,000Easy
Practice
Practice drill

Calculate the sum of integers from 1 to 1,000,000 using PostgreSQL aggregation and filtering.

AlgorithmsVirtu Financial
SQL Duplicate DetectionEasy
Practice
Practice drill

Find duplicate customer profiles by grouping on identifying fields and returning only repeated records.

Group ByHavingAggregationsAdtalem Global EducationAmerisave MortgageCitrine Informatics
The finish line: interview-readyComplete all 40 questions plus 2 hands-on drills to finish this plan.