Progress · 0/5 phases
🏗️ 🏗️ 90-Day HLD Roadmap — High-Level System Design
3 min read · Notion
🏗️ Frontend → Systems Engineer transition. 90 days. 5 phases. High-Level Design mastery from first principles to staff-engineer level.
📌 How to use this template
- Work through phases in order — each phase builds directly on the last
- Every day: study the topic → sketch a design → log one mistake you caught yourself making
- Use the Daily Tracker database to stay accountable
- Open each Phase page for full topic breakdowns, projects, real-system references, and mistake corrections
💡 The #1 rule of HLD: Never draw a single box until you've written down the requirements and estimated the scale. Senior engineers spend 40% of a design session on constraints before touching architecture.
🗺️ Roadmap at a glance
| Phase | Days | Focus | Projects |
|---|---|---|---|
| Phase 1 — Foundations | Days 1–15 | Vocabulary, estimation, CAP, building blocks | URL Shortener requirements, Estimation CLI |
| Phase 2 — Core Components | Days 16–35 | Caching, queues, CDN, load balancing, search | Caching layer design, Rate limiter doc |
| Phase 3 — Distributed Patterns | Days 36–55 | Sagas, consistency, sharding, consensus | Job scheduler, Saga design, Sharding doc |
| Phase 4 — Real System Designs | Days 56–75 | Twitter, Uber, Netflix, Payments, WhatsApp | Full HLD docs, Mock interview |
| Phase 5 — Expert Systems | Days 76–90 | Multi-region, migrations, staff review | Notification system, Architecture critique |
⚡ The RESHADED Framework
Use this structure for every system design — interview or production.
- R — Requirements (functional + non-functional)
- E — Estimation (QPS, storage, bandwidth, memory)
- S — Storage schema (which DB, why, what schema)
- H — High-level design (component diagram)
- A — APIs (REST/gRPC endpoints, contracts)
- D — Detailed design (deep dive on 2–3 critical components)
- E — Evaluate (failure scenarios, bottlenecks, tradeoffs)
- D — Distinguish (what makes your design better than the naive approach)
📊 My progress
- Current phase: Phase 1
- Current day: Day 1 of 90
- Systems fully designed: 0 / 12
- Design docs written: 0
🔖 Quick links
- 📐 Phase 1 — Foundations of System Design
- ⚙️ Phase 2 — Core System Components
- 🔀 Phase 3 — Distributed System Patterns
- 🏛️ Phase 4 — Real System Designs
- 🧠 Phase 5 — Expert-Level Systems
📐 Latency numbers every designer must know
| Operation | Latency |
|---|---|
| L1 cache reference | ~1 ns |
| L2 cache reference | ~4 ns |
| RAM reference | ~100 ns |
| SSD read (4KB) | ~100 µs |
| Read 1MB from SSD | ~1 ms |
| Network round-trip (same DC) | ~0.5 ms |
| Network round-trip (cross-region) | ~100 ms |
| Read 1MB from network | ~10 ms |
| HDD seek | ~10 ms |
These numbers drive every architecture tradeoff. Memorise them. Use them in every estimation.
📅 HLD Daily Tracker