Meta Backend Engineer Interview Questions (2026)

1. 1Recruiter screen30 minEasy

   Process overview, level calibration, and prep guidance — Meta recruiters actively coach on round formats.

2. 2Technical screen45 minHard

   Two DSA problems in 45 minutes on a plain shared editor with no autocomplete or execution.

3. 3Coding round ('Ninja')45 minHard

   Two more problems at loop difficulty; clean near-compilable code and verbalized complexity analysis expected.

4. 4System design ('Pirate')45 minHard

   Design a Meta-scale product system (feed, Stories, chat) with emphasis on read-heavy fan-out, caching, and data modeling.

5. 5Behavioral ('Jedi')45 minMedium

   Deep past-experience discussion on conflict, growth, and impact aligned to Meta values; graded as a real signal round.

1. Q1

   In a practical product design drill, answer this: Design classes for assigning Marketplace users to experiments

   MediumLow Level DesignA/B experiment SDK

   How to answer: Model Experiment, Variant, Allocation, EligibilityRule, AssignmentService, and ExposureLogger; use deterministic hashing and log exposures once. Optimize for simple, scalable product objects and fast iteration.

2. Q2

   In a Meta product/system design round, answer this: Design an experimentation platform for WhatsApp

   HardHigh Level DesignA/B testing platform

   How to answer: Use deterministic assignment, experiment config service, exposure logging, metrics pipeline, guardrails, and analysis dashboards; handle mutually exclusive experiments. Discuss read-heavy fanout, ranking, privacy, and product trade-offs.

3. Q3

   In a practical product design drill, answer this: Design a reusable API client for Reels with auth refresh and request signing

   MediumLow Level DesignAPI client with auth

   How to answer: Separate HttpClient, AuthProvider, TokenStore, RequestSigner, RetryPolicy, and Serializer; refresh tokens safely and avoid logging secrets. Optimize for simple, scalable product objects and fast iteration.

4. Q4

   In a Meta product/system design round, answer this: Design an API gateway for Instagram Stories backend services

   MediumHigh Level DesignAPI gateway

   How to answer: Handle auth, routing, rate limits, request validation, retries/timeouts, observability, and versioning. Keep business logic out of the gateway. Discuss read-heavy fanout, ranking, privacy, and product trade-offs.

5. Q5

   In a fast 45-minute Meta-style coding round, solve this: Code a mapper from a raw Marketplace API response to a stable internal model

   HardCodingAPI response mapper

   How to answer: Validate required fields, provide defaults for optional fields, isolate external schema changes, and test unknown fields and backward compatibility. Keep the solution direct and code-ready under time pressure.

6. Q6

   In a Meta product/system design round, answer this: Design an ad-serving system for Groups

   HardHigh Level DesignAd serving

   How to answer: Separate request routing, candidate retrieval, auction/ranking, budget pacing, frequency capping, logging, and fraud detection; optimize p99 latency. Discuss read-heavy fanout, ranking, privacy, and product trade-offs.

7. Q7

   In a fast 45-minute Meta-style coding round, solve this: Infer character order from sorted News Feed labels in an unknown alphabet

   HardDSAAlien dictionary

   How to answer: Build precedence edges from first differing characters, then topologically sort. O(total characters); detect invalid prefixes and cycles. Keep the solution direct and code-ready under time pressure.

8. Q8

   In a Getting-to-Know-You conversation, answer this: Tell me about a time you had to deliver a Threads project with ambiguous requirements

   MediumBehavioralAmbiguity

   How to answer: Use STAR: clarify the ambiguity, list options, align stakeholders, deliver an MVP, quantify outcome, and mention what you changed after learning. Emphasize impact, speed, and cross-functional collaboration.

9. Q9

   In a fast 45-minute Meta-style coding round, solve this: Write code to call multiple Groups services concurrently and return partial results safely

   MediumCodingAsync fanout

   How to answer: Use async tasks/futures with per-call timeouts, collect successes and errors separately, limit concurrency, and preserve result ordering if required. Keep the solution direct and code-ready under time pressure.

10. Q10

    In a practical product design drill, answer this: Design a low-level audit logger for Threads administrative actions

    MediumLow Level DesignAudit log component

    How to answer: Model AuditEvent, Actor, Target, Metadata, Sink, and Redactor; ensure append-only semantics and safe handling of PII. Optimize for simple, scalable product objects and fast iteration.

11. Q11

    In a fast 45-minute Meta-style coding round, solve this: Implement autocomplete over a static set of Marketplace terms

    MediumCodingAutocomplete function

    How to answer: Build a trie or sorted array with binary-search prefix range; return ranked top N; test empty prefix, Unicode, and tie ordering. Keep the solution direct and code-ready under time pressure.

12. Q12

    In a fast 45-minute Meta-style coding round, solve this: Generate all valid configurations for a small Reels rule set with constraints

    MediumDSABacktracking combinations

    How to answer: Use DFS/backtracking, pruning invalid partial states early. Complexity is exponential; explain pruning and output-size limits. Keep the solution direct and code-ready under time pressure.

13. Q13

    In a fast 45-minute Meta-style coding round, solve this: Validate nested delimiters in a Threads expression language

    MediumDSABalanced parentheses

    How to answer: Use a stack of opening delimiters and match each closing delimiter. O(n), O(n); reject mismatches and leftover openings. Keep the solution direct and code-ready under time pressure.

14. Q14

    In a Getting-to-Know-You conversation, answer this: Give an example of balancing ship speed and engineering quality for WhatsApp

    MediumBehavioralBalancing speed and quality

    How to answer: State deadline and risks, define acceptable quality bar, ship safe slice, add follow-up debt plan, and measure post-launch outcomes. Emphasize impact, speed, and cross-functional collaboration.

15. Q15

    In a fast 45-minute Meta-style coding round, solve this: Implement a batcher for Groups events that flushes by size or time

    HardCodingBatching helper

    How to answer: Buffer events, flush when max size or max age is reached, make flush thread-safe, and test empty, timer, size, and failure behavior. Keep the solution direct and code-ready under time pressure.

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Be fast and correct on coding; for design, drive the conversation; prepare impact-focused behavioral stories

Indicative Backend Engineer pay in India: ~₹10–45 LPA (role-level range, not a Meta-specific figure).

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