Learn System Design by Building, Not Reading
ScaleDojo is the hands-on system design practice platform. Drag cloud components onto an interactive canvas, connect them with data flows, and get instant scoring from a deterministic engine and AI architect reviewer. 338+ challenges across six labs. Free to start.
What is ScaleDojo?
ScaleDojo is an interactive system design learning platform built for software engineers who want to practice designing distributed systems hands-on. Instead of passively reading about how a URL shortener or payment gateway works, you design one yourself on a visual canvas and receive automated feedback.
The platform offers four distinct labs covering the full spectrum of system design: High-Level Design (HLD) architecture with 70 progressive levels, Low-Level Design (LLD) database schema modeling with 50 missions, API Design with 50 levels of REST API practice, and a GenAI Systems Lab with 50+ pipeline design challenges covering RAG, vector search, LLM agents, and production AI architectures.
Every submission is evaluated by a deterministic scoring engine across five dimensions: correctness, scalability, reliability, cost efficiency, and latency optimization. An AI Architect reviewer (powered by Google Gemini) then provides specific feedback on your topology, identifies single points of failure, and suggests improvements.
Four Interactive Labs
HLD Architecture Lab
70 LevelsDesign high-level distributed system architectures. Drag real cloud components onto a canvas - load balancers, databases, caches, message queues, CDNs - and connect them with data flows. Design URL shorteners, rate limiters, chat systems, video streaming platforms, and more.
LLD Schema Design Lab
50 LevelsDesign database schemas on an interactive ER diagram canvas. Model entities, define columns with types and constraints, draw relationships. Covers normalization (1NF-BCNF), indexing strategies, and real-world data modeling for e-commerce, social networks, and more.
API Design Lab
50 LevelsDesign production REST APIs. Define endpoints, HTTP methods, request/response schemas, error handling, pagination, authentication, and versioning patterns. Progressive difficulty from basic CRUD to complex multi-resource APIs with rate limiting.
GenAI Systems Lab
50+ ChallengesDesign generative AI pipelines. Build RAG systems, LLM-powered agents, vector search implementations, prompt engineering chains, AI gateways, and production deployment architectures. Scored on cost efficiency, latency, and safety compliance.
How ScaleDojo Works
Pick a Challenge
Choose from 338+ system design challenges across HLD, LLD, API Design, GenAI, SQL Lab, and Forge. Each level presents a real-world system to design with clear requirements and constraints.
Design on the Canvas
Drag cloud components from the drawer onto an interactive canvas. Connect them with directed edges representing data flow. For LLD, create entities and define schemas. For API, define endpoints and schemas.
Get Instant Scoring
A deterministic engine scores your design across 5 dimensions: correctness, scalability, reliability, cost efficiency, and latency. No waiting - results appear immediately.
AI Architect Review
An AI reviewer analyzes your complete topology and provides specific feedback: bottlenecks identified, improvements suggested, real-world comparisons drawn. Like having a principal engineer review your design.
How ScaleDojo Compares to Other Resources
| Resource | Type | Approach | Reading & History Content | Hands-On Practice |
|---|---|---|---|---|
| ScaleDojo | Interactive Platform | Build architectures on canvas, get scored - plus read the Origin Files and Engineering Blog | ||
| ByteByteGo | Visual Guides + Newsletter | Read illustrated explanations | - | |
| System Design Primer | GitHub Study Guide | Read markdown documentation | - | |
| Grokking (Educative) | Text Course | Read guided text lessons | - | |
| DDIA (Kleppmann) | Book | Read distributed systems theory | - |
ScaleDojo is the only platform where you actually design systems on a canvas and receive automated scoring. The best approach: read theory from books/blogs, then practice on ScaleDojo.
Who Uses ScaleDojo
Interview Candidates
Engineers preparing for system design interview rounds at FAANG, startups, and top tech companies.
Senior Engineers
Working developers who want to sharpen their architecture skills and validate design intuitions against scoring.
Tech Leads & Architects
Leaders who need to pressure-test design patterns and explore trade-offs before committing to production decisions.
Free Resources
Beyond the labs, ScaleDojo maintains a free learning roadmap, an engineering blog, an origin-story series, and a reference wiki - no paywall, no signup required.
Learning Roadmap
A guided skill tree from networking basics to planet-scale architectures, linked to relevant levels and blog posts.
Engineering Blog
150+ deep-dive articles tracing how real systems evolved - from ARPANET to modern distributed architectures.
The Origin Files
Chapter-by-chapter histories of HLD, LLD, API Design, GenAI, and Forge - why every pattern and component exists.
System Design Wiki
A searchable reference manual covering trade-offs, real-world blueprints, and production-tested patterns.
Topics Covered
Follow Along
We ship updates constantly - see the changelog or follow us here.
Start Designing Systems Today
37+ free levels across all four labs. No credit card required. Build your first architecture in under 5 minutes.