Hireable 100

100 concepts every interview-ready engineer should know, organized by track. Free, open-source, contributions welcome.

How to use

• Pick the track that matches your target role.
• For each concept, you should be able to (a) define it in one sentence, (b) cite a real-world tradeoff, (c) recall a story or example.

Track 1 — Data Engineering (17)

1. ACID properties (atomicity, consistency, isolation, durability)
2. Star schema vs snowflake schema
3. SCD Type 1 / 2 / 3
4. Partitioning vs bucketing
5. Z-ordering / liquid clustering
6. CDC (change data capture)
7. Idempotent writes
8. Lakehouse architecture
9. Medallion (bronze/silver/gold)
10. Backfill strategies (replay vs reset)
11. Watermarking in stream processing
12. Exactly-once vs at-least-once semantics
13. Skew handling (salting, broadcast)
14. Cost vs latency tradeoffs in jobs clusters
15. Data contracts and schema registry
16. Lineage and column-level dependency
17. DR/RPO/RTO for analytical platforms

Track 2 — ML / AI Engineering (17)

1. Bias-variance tradeoff
2. Train/val/test split discipline
3. Cross-validation flavors (k-fold, time-series)
4. Loss functions (MSE, cross-entropy, contrastive)
5. Optimizers (SGD, Adam, AdamW)
6. Regularization (L1/L2, dropout, weight decay)
7. Data leakage and how to detect it
8. Feature store (online vs offline)
9. Embedding spaces and similarity metrics
10. RAG architecture
11. Prompt engineering vs fine-tuning vs retrieval
12. LLM eval methods (perplexity, BLEU, human pairwise)
13. Quantization and distillation
14. Online inference latency budgets
15. Drift detection (data, concept, label)
16. Shadow vs canary model deployment
17. Feedback loops and label noise

Track 3 — Backend / Distributed Systems (17)

1. CAP theorem
2. Consistency models (strong, eventual, causal)
3. Quorum reads/writes
4. Leader election (Raft, Paxos basics)
5. Idempotency and dedupe keys
6. Backpressure and circuit breakers
7. Rate limiting (token bucket, leaky bucket)
8. Caching layers (read-through, write-through, write-back)
9. Pub/sub vs queue semantics
10. Event sourcing
11. CQRS
12. Sagas and compensating transactions
13. Multi-region replication
14. Sharding strategies (hash, range, directory)
15. Service mesh basics
16. SLO / SLI / error budget
17. Observability: logs vs metrics vs traces

Track 4 — Frontend / Product Engineering (17)

1. CSR vs SSR vs SSG vs ISR
2. Hydration costs and partial hydration
3. Critical rendering path
4. Web Vitals (LCP, INP, CLS)
5. Accessibility (WCAG, ARIA basics)
6. Form validation patterns
7. State management (Redux, Zustand, signals)
8. Suspense and concurrent rendering
9. Streaming SSR
10. Edge vs origin rendering
11. Build-time vs runtime feature flags
12. A/B testing infra basics
13. Analytics events naming conventions
14. CSP and XSS hardening
15. Cookie semantics (HttpOnly, SameSite)
16. Image optimization (responsive, AVIF/WebP)
17. PWA fundamentals (manifest, service worker)

Track 5 — Behavioral / Leadership (16)

1. STAR method
2. Quantifying impact (the metric-first story)
3. Influencing without authority
4. Conflict resolution patterns
5. Mentorship and growing engineers
6. Tech lead vs IC tradeoffs
7. Driving technical strategy
8. Scoping and prioritization
9. Communicating to non-technical stakeholders
10. Postmortem culture (blameless analysis)
11. Hiring bar / leveling
12. Performance management basics
13. Roadmap vs backlog discipline
14. Estimation and uncertainty bands
15. Decision-making frameworks (RAPID, DACI)
16. Diversity, equity, inclusion in practice

Track 6 — System Design (16)

1. Functional vs non-functional requirements
2. Capacity estimation (back-of-envelope)
3. Read-heavy vs write-heavy patterns
4. Hot-key mitigation
5. Storage choice tradeoffs (SQL, KV, doc, wide-column, search)
6. Indexing strategies
7. Geospatial design (geohash, S2, h3)
8. Notifications fanout
9. Feed ranking architecture
10. Search architecture (inverted index, ANN)
11. Real-time analytics pipelines
12. Multi-tenant isolation strategies
13. Consistency vs availability (real-world picks)
14. Graceful degradation patterns
15. Migration playbooks (dual-write, shadow read)
16. Cost-aware architecture review checklist

Contributing

Pull requests welcome at the Hireable GitHub repo. Add tracks, swap entries, link deep dives.