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. 486 challenges across seven 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. ScaleDojo is built and operated by Scaling Future Private Limited.
The platform offers seven labs covering the full spectrum of system design: High-Level Design (HLD) architecture with 100 progressive levels, a Database Lab combining LLD schema design (80 missions, ER diagrams and normalization) with SQL practice (50 detective noir cases - JOINs, window functions, CTEs), API Design with 50 levels of REST API practice, a GenAI & AI Lab track - GenAI Systems (50 pipeline design challenges covering RAG, vector search, LLM agents, and production AI architectures) and AI Lab (72 Python challenges implementing ML algorithms from scratch: gradient descent, decision trees, neural networks, and a scalar autograd engine), and the Forge Algorithm Lab with 76 coding challenges.
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.
Five Lab Groups, 486 Challenges
HLD Architecture Lab
100 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.
Database Lab
130 Levels (LLD Schema + SQL)Two complementary tracks in one: LLD schema design (80 missions - ER diagrams, normalization 1NF-BCNF, indexing, foreign key constraints on an interactive canvas) and SQL Lab (50 detective noir cases - SELECT, JOINs, GROUP BY, window functions, CTEs, and query optimization).
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 & AI Lab
122 Levels (GenAI Systems + AI Lab)Two AI tracks: GenAI Systems (50 challenges - design RAG pipelines, LLM agents, vector search, and production AI architectures) and AI Lab (72 Python challenges - implement ML algorithms from scratch: gradient descent, k-means, decision trees, neural networks, and a scalar autograd engine, autograded instantly).
Forge Algorithm Lab
76 LevelsDSA coding interview prep: implement heaps, LRU caches, Bloom filters, consistent hashing, WAL logs, circuit breakers, and Raft consensus from scratch. Submissions run in a real sandbox in Python or Java.
How ScaleDojo Works
Pick a Challenge
Choose from 486 challenges across HLD, Database Lab (LLD Schema + SQL), API Design, GenAI & AI Labs, and Forge. Each level presents a real-world system to design with clear requirements and constraints.
Design on the Canvas
Drag cloud components onto an interactive canvas and connect them with data flows. Database Lab: create entities and define schemas. API: define endpoints and contracts. AI Lab: write Python code implementing ML algorithms.
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
Start Designing Systems Today
47+ free levels across all six labs. No credit card required. Build your first architecture in under 5 minutes.