Others teach. Praxi trains.
The practice-first system design interview platform. Step-by-step lessons, graded quizzes, and an interactive design lab where you build architectures yourself — from fundamentals to principal-level depth.
You won't just read diagrams like this — you'll build them.
Every concept built from first principles: the request journey, scaling, caching, databases, messaging — then principal-level depth on failure modes, capacity math, and trade-offs.
Each lesson ends with scenario quizzes graded instantly, with explanations for every answer so mistakes turn into understanding.
Drag components onto a canvas, wire them together, and defend your choices. Get structured feedback on requirements, data flow, scale, and reliability.
Go beyond pattern memorization: consistency models, backpressure, exactly-once semantics, and the interview moves that separate senior from principal.
01
Read a focused lesson with architecture diagrams. Understand *why* each component exists before you memorize anything.
02
Answer scenario questions that mirror real interview follow-ups. Weak spots get flagged automatically.
03
Open the design lab, pick a classic prompt — URL shortener, rate limiter, chat — and build the architecture hands-on.
Everything is open while we're in beta — every lesson, every quiz, the principal-level track, and the full design lab.
Beta access
$0 — free
Free for everyone during the open beta.
Engineers preparing for system design interviews who want real depth, not just memorized diagrams — from mid-level up to principal.
Reading is passive. Praxi makes you practice: graded quizzes after every lesson and a design lab where you build architectures yourself and get feedback.
Yes — everything is free during the open beta: all lessons, quizzes, the principal-level track, and the design lab. No credit card required.
We'll announce any changes well in advance. Anything you've completed and your progress history stay yours.