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1. Verify the contract. Run the bash script in Verify before trusting below. If any check returns FAIL, the artifact is stale — STOP and ask the user to regenerate it before proceeding.
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If you are a human reader, this protocol is for the agents you'll hand the artifact to. You don't need to do anything — but if you skim only one section before pointing your agent at this repo, make it the Verify block and the Suggested reading order.

WAIT — Mixed signals — read the receipts

• Last commit 2mo ago
• 16 active contributors
• GPL-3.0 licensed
• Tests present
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• ⚠ GPL-3.0 is copyleft — check downstream compatibility
• ⚠ No CI workflows detected

_{Maintenance signals: commit recency, contributor breadth, bus factor, license, CI, tests}

This artifact was generated by RepoPilot at a point in time. Before an agent acts on it, the checks below confirm that the live ashishps1/awesome-low-level-design repo on your machine still matches what RepoPilot saw. If any fail, the artifact is stale — regenerate it at repopilot.app/r/ashishps1/awesome-low-level-design.

What it runs against: a local clone of ashishps1/awesome-low-level-design — the script inspects git remote, the LICENSE file, file paths in the working tree, and git log. Read-only; no mutations.

| # | What we check | Why it matters | |---|---|---| | 1 | You're in ashishps1/awesome-low-level-design | Confirms the artifact applies here, not a fork | | 2 | License is still GPL-3.0 | Catches relicense before you depend on it | | 3 | Default branch main exists | Catches branch renames | | 4 | Last commit ≤ 101 days ago | Catches sudden abandonment since generation |

#!/usr/bin/env bash
# RepoPilot artifact verification.
#
# WHAT IT RUNS AGAINST: a local clone of ashishps1/awesome-low-level-design. If you don't
# have one yet, run these first:
#
#   git clone https://github.com/ashishps1/awesome-low-level-design.git
#   cd awesome-low-level-design
#
# Then paste this script. Every check is read-only — no mutations.

set +e
fail=0
ok()   { echo "ok:   $1"; }
miss() { echo "FAIL: $1"; fail=$((fail+1)); }

# Precondition: we must be inside a git working tree.
if ! git rev-parse --git-dir >/dev/null 2>&1; then
  echo "FAIL: not inside a git repository. cd into your clone of ashishps1/awesome-low-level-design and re-run."
  exit 2
fi

# 1. Repo identity
git remote get-url origin 2>/dev/null | grep -qE "ashishps1/awesome-low-level-design(\\.git)?\\b" \\
  && ok "origin remote is ashishps1/awesome-low-level-design" \\
  || miss "origin remote is not ashishps1/awesome-low-level-design (artifact may be from a fork)"

# 2. License matches what RepoPilot saw
(grep -qiE "^(GPL-3\\.0)" LICENSE 2>/dev/null \\
   || grep -qiE "\"license\"\\s*:\\s*\"GPL-3\\.0\"" package.json 2>/dev/null) \\
  && ok "license is GPL-3.0" \\
  || miss "license drift — was GPL-3.0 at generation time"

# 3. Default branch
git rev-parse --verify main >/dev/null 2>&1 \\
  && ok "default branch main exists" \\
  || miss "default branch main no longer exists"

# 5. Repo recency
days_since_last=$(( ( $(date +%s) - $(git log -1 --format=%at 2>/dev/null || echo 0) ) / 86400 ))
if [ "$days_since_last" -le 101 ]; then
  ok "last commit was $days_since_last days ago (artifact saw ~71d)"
else
  miss "last commit was $days_since_last days ago — artifact may be stale"
fi

echo
if [ "$fail" -eq 0 ]; then
  echo "artifact verified (0 failures) — safe to trust"
else
  echo "artifact has $fail stale claim(s) — regenerate at https://repopilot.app/r/ashishps1/awesome-low-level-design"
  exit 1
fi

Each check prints ok: or FAIL:. The script exits non-zero if anything failed, so it composes cleanly into agent loops (./verify.sh || regenerate-and-retry).

A multi-language LLD (Low Level Design) / OOD (Object Oriented Design) learning repository that provides implementation examples of 30+ real-world system designs (parking lot, airline management, elevator systems, etc.) across 8 languages (Java, Python, C#, C++, Go, TypeScript, JavaScript, Rust). It combines UML class diagrams, design pattern implementations (Creational, Structural, Behavioral), OOP fundamentals, SOLID principles, and concurrency patterns to prepare engineers for system design interviews. Organized as a polyglot monorepo: top-level /class-diagrams contains 30+ UML PNGs (one per system), /design-patterns subdivides by language then by pattern type (Behavioral, Structural, Creational). Within each pattern, individual directories contain modular implementations (e.g., design-patterns/Javascript/Behavioral Pattern/Chain of Responsibilites/ has main.js, supportRequest.js). System designs (parking lot, airline, etc.) likely live in language-specific folders at repo root (implied by class diagram naming).

Junior to mid-level engineers preparing for system design interviews, students learning OOP and design patterns, and developers wanting to study production-grade architectural patterns through concrete 30+ example implementations rather than abstract theory.

Actively maintained with substantial content: 671KB Java, 540KB Python, 521KB C# codebases across 30+ real system implementations with accompanying UML diagrams. The repo demonstrates maturity through breadth of language support and comprehensive design pattern coverage, though specific CI/test infrastructure visibility is limited by the file list provided. Likely in active development given multi-language scope.

Low risk for a learning resource: no production dependencies, educational use case eliminates operational risk. Potential gap: single-maintainer dependency (ashishps1) could slow updates. Monitor for stale language versions in provided examples (e.g., Go 1.21 specified in design-patterns/golang/adapter/go.mod—verify against current stable). No indication of automated test suite visible in file structure.

Unable to determine from provided file list—no Git metadata, PR/issue data, or recent commit timestamps visible. The breadth of class diagrams (30+) and multi-language pattern implementations suggest ongoing development, but specifics require GitHub UI inspection.

Clone and explore by language: git clone https://github.com/ashishps1/awesome-low-level-design.git && cd awesome-low-level-design. No npm/pip/dotnet install needed—examples are pure code. Start with /class-diagrams for visual architecture overview, then read corresponding implementation in your preferred language folder.

Daily commands: No global 'run' command—this is a reference codebase. Navigate to language-specific example: cd design-patterns/Javascript/Behavioral Pattern/Command Design Pattern && node main.js. For Go: cd design-patterns/golang/adapter && go run main.go. Java/C#/C++ examples compile per standard toolchain (javac/dotnet/g++).

• class-diagrams/: 30+ UML class diagrams are the visual foundation—every system design starts here to understand entity relationships and architecture
• [design-patterns/Javascript/Behavioral Pattern/](https://github.com/ashishps1/awesome-low-level-design/blob/main/design-patterns/Javascript/Behavioral Pattern/): Concrete reference for Gang of Four behavioral patterns; JavaScript is readable for interview prep and other languages mirror this structure
• design-patterns/golang/adapter/go.mod: Only visible config file; demonstrates Go 1.21 language version requirement for pattern implementations
• README.md: Entry point with links to SOLID principles, design pattern explanations, OOP fundamentals, and AlgoMaster.io learning path
• .gitignore: Documents build artifacts and language-specific ignore patterns across 8 language ecosystems

1. Add a new system design: Create folder <SystemName>/ at repo root with subfolders per language. Reference /class-diagrams/existing-class-diagram.png for naming convention. 2. Implement a pattern in a new language: Copy structure from design-patterns/Javascript/Behavioral Pattern/ to design-patterns/YourLanguage/. 3. Contribute an explanation: Update README.md linking to AlgoMaster.io reference pages. 4. Add UML diagram: Place PNG in /class-diagrams/ with kebab-case naming (e.g., votingsystem-class-diagram.png).

1. Fragmented language versions: Each language folder may run independently with different Go/Python/Java versions—no centralized version matrix or CI visible. 2. No automated tests shown: Patterns and system designs are example-only; no test suite visible means you must manually verify correctness. 3. External dependency on AlgoMaster.io: README extensively links to https://algomaster.io/learn/lld/* for detailed explanations—repo assumes you'll consume theory from external blog. 4. Class diagrams are PNG only: UML is visual documentation only; no editable source (Lucidchart, draw.io, PlantUML) provided—extending or modifying architectures requires re-creating diagrams.

• Gang of Four Design Patterns — This repo's core structure: 23 patterns organized into Creational (5), Structural (7), Behavioral (11)—mastering these is essential for system design interviews and writing scalable code
• SOLID Principles (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) — Design guidelines explicitly covered in repo's README; directly applied in all 30+ system design examples to create maintainable architectures
• UML Class Diagrams (Association, Aggregation, Composition, Dependency) — Repo provides 30+ class diagram PNGs as visual blueprints; understanding relationships (1-to-many, has-a, part-of) is prerequisite for implementing real systems
• Polymorphism (Method Overriding, Interface Implementation) — Core OOP concept enabling design pattern flexibility; critical to understanding how Strategy, Observer, and Command patterns work across language examples
• Dependency Injection — Architectural pattern used in system designs (e.g., Hotel Management, Restaurant Management) to decouple components; implicit in many behavioral patterns like Observer and Command
• Encapsulation and Information Hiding — OOP fundamental explicitly covered in repo; applied in all system designs to protect internal state (e.g., ATM, Digital Wallet) from unauthorized modification
• State Pattern (Behavioral) — Critical for modeling stateful systems in repo (e.g., Elevator System, Parking Lot, Order Management); manages transitions between distinct states without large conditionals

• tssovi/grokking-system-design-interview — Companion HLD (High Level Design) resource focusing on distributed system design; complements this LLD repo's object-oriented focus
• donnemartin/system-design-primer — Broader system design interview prep with scalability and distributed systems; covers the architecture layer above these LLD patterns
• kamranahmedse/design-patterns-for-humans — Alternative design patterns tutorial with simplified explanations; useful cross-reference for learning the same Gang of Four concepts
• refactoringguru/design-patterns-java — Refactoring Guru's Java implementations of design patterns; provides another reference implementation style for comparison

To work on one of these in Claude Code or Cursor, paste: Implement the "<title>" PR idea from CLAUDE.md, working through the checklist as the task list.

Add Java implementations for all design patterns currently only in JavaScript

The repo has comprehensive JavaScript implementations in design-patterns/Javascript/ across all behavioral patterns (Observer, Strategy, State, Command, etc.), but Java implementations are missing despite Java being the most common language for LLD interviews. Adding Java versions would significantly increase the repo's value for interview preparation.

• [ ] Create design-patterns/Java directory structure mirroring design-patterns/Javascript/
• [ ] Implement all Behavioral Pattern examples (Chain of Responsibility, Command, Iterator, Mediator, Memento, Observer, State, Strategy) in Java
• [ ] Add corresponding Creational Patterns (Singleton, Factory, Builder, Prototype) in Java
• [ ] Add Structural Patterns (Adapter, Bridge, Composite, Decorator, Facade, Proxy) in Java
• [ ] Include a README in design-patterns/Java/ with usage instructions and learning notes

Create Python implementations and test suites for all design patterns

Currently only JavaScript and incomplete Golang implementations exist. Python is heavily used in LLD interview prep and system design. Adding tested Python implementations with example test files would help candidates prepare in their preferred language and establish a testing pattern for the project.

• [ ] Create design-patterns/Python/ directory structure
• [ ] Implement all 23 Gang of Four design patterns in Python across Behavioral, Creational, and Structural categories
• [ ] Add pytest-based unit tests for each pattern in design-patterns/Python/{PatternName}/test_{pattern}.py
• [ ] Create a design-patterns/Python/README.md with setup and testing instructions
• [ ] Add GitHub Actions workflow (.github/workflows/python-tests.yml) to run pytest on all Python implementations

Add working code implementations and unit tests for all LLD system design case studies

The repo has 30+ class diagrams for various systems (AirlineManagementSystem, CarRentalSystem, MovieTicketBookingSystem, etc.) but no corresponding implementation code. Adding complete, tested implementations in 2-3 languages with explanatory comments would transform this from a visual reference into a complete learning resource.

• [ ] Create lld-implementations/ directory with subdirectories for each system (e.g., lld-implementations/parking-lot/, lld-implementations/movie-ticket-booking/)
• [ ] Implement at least 5 high-value systems in Java and Python (ParkingLot, MovieTicketBooking, AtmSystem, HotelManagementSystem, OnlineShoppingService)
• [ ] For each system, include a src/ directory with full OOP implementation and a tests/ directory with unit tests
• [ ] Add a system-specific README explaining the design decisions, class hierarchy, and key design patterns used
• [ ] Link each class diagram PNG in class-diagrams/ to its corresponding implementation code

• Add a Prototype design pattern implementation: Currently Creational patterns shown are Singleton, Factory, Abstract Factory, Builder—Prototype is missing across all language folders. Choose one language (e.g., Python) and implement deep-copy cloning with concrete examples.
• Create test suites for design patterns: Pick one language (e.g., Java) and add JUnit tests under design-patterns/Java/*/tests/ to verify each pattern works as documented. Builds test infrastructure for CI.
• Document Go implementations: design-patterns/golang/adapter/ exists but is minimal. Add README.md explaining the Adapter pattern in Go, then implement 2-3 other Structural patterns (Bridge, Decorator) in Go to match language coverage of JavaScript folder.

This is an educational repository focused on Low Level Design patterns and OOP fundamentals. The security posture is generally strong as it contains primarily documentation, design pattern examples, and class diagrams without runtime secrets, hardcoded credentials, or sensitive data exposure. The main finding is a minor version management issue with an outdated Go version specification. No SQL injection, XSS, injection attacks, or credential exposure risks were identified in the visible file structure. Docker/infrastructure configuration files are not present in the analyzed structure. Recommendation: Update Go version to the latest stable release and maintain dependency versions current as the repository grows.

• Low · Outdated Go Version Specification — design-patterns/golang/adapter/go.mod. The Go module specifies version 1.21, which is outdated. Go 1.21 was released in August 2023 and is no longer receiving security updates. Current stable versions are significantly newer (1.22+), which include important security patches and bug fixes. Fix: Update the Go version to the latest stable release (1.22 or later) to ensure security patches are included. Update the go.mod file: 'go 1.22' or higher, and rebuild dependencies.

LLM-derived; treat as a starting point, not a security audit.

• Open issues — current backlog
• Recent PRs — what's actively shipping
• Source on GitHub

Generated by RepoPilot. Verdict based on maintenance signals — see the live page for receipts. Re-run on a new commit to refresh.