Interview preparation for software engineers
Walk into the interview with a design you can defend.
Clotiv teaches system design and behavioral interviews the way strong candidates actually prepare: 59 lessons, 21worked case studies, and an AI tutor that has read the lesson you’re on.
36 lessons are free to read, signed in or not. No card required.
Available today
Two tracks, one place to prepare
Lessons that build up to real prompts
44 system design lessons — fundamentals, building blocks, and 21 case studies from URL shortener to an LLM inference service and an AI agent platform. 15 behavioral lessons turn your own stories into answers.
AI Help that has read the lesson
Ask why a design choice was made, push on a trade-off, or get a follow-up question. The tutor is grounded in the lesson text you’re reading and can search the web when the answer isn’t in it.
Notes and progress that stay with you
Save versioned notes per topic, mark lessons read, and pick up where you left off on any device.
Plans
Start free, upgrade when the lessons run out
Free
$0Everything you need to find out whether Clotiv is for you.
- 36 open lessons, including the most-asked case studies
- A monthly allowance of AI Help
- Notes and reading progress
Plus
See plansThe full library and room to use the AI tutor every day.
- All 59 lessons, including every worked case study
- A generous monthly AI Help allowance, with top-ups
- Job application tracking, included when it ships
Pro
See plansFor a serious loop: unlimited AI Help on every lesson.
- Everything in Plus
- Unlimited AI Help on /learn (fair use)
- Priority access to new lessons
Prices in USD, billed by our payment processor. Cancel anytime; access continues to the end of the period. Details in the Terms.
On the roadmap
Coming soon
These are being built on the same lesson corpus. None of them is available yet — we say so here rather than on a pricing page.
Job application tracking
Coming soonKeep every application, contact and next step in one place. Included with Plus and Pro when it ships.
Question bank
Coming soonThe questions behind each lesson, filterable by company, level and topic, with model answers.
Mock interviews
Coming soonTimed, AI-run system design and behavioral rounds with a written debrief against the lesson rubric.
Live interview helper
Coming soonReal-time prompts during a practice or real interview, built on the same lesson corpus.
Start with the most-asked questions
System design interview questions, worked end to end — free
- Design a URL shortener like TinyURL or Bitly.20 min
- Design a distributed rate limiter for an API.18 min
- Design Twitter's news feed.20 min
- Design a real-time chat system like WhatsApp.22 min
- Design a video streaming platform like YouTube.20 min
- Design a service that serves a large language model to many concurrent users.19 min
- Design a platform that runs autonomous AI agents with tool access, safely and at scale.19 min
Questions people ask
- What is Clotiv?
- Clotiv is an interview-preparation site for software engineers. It has 59 lessons across two tracks — 44 on system design (fundamentals, building blocks and 21 worked case studies) and 15 on behavioral interviews — plus an AI tutor that answers questions using the text of the lesson you are reading.
- Is Clotiv free?
- Yes to start. 36 of the 59 lessons are free to read without an account, including the most-asked system design case studies. A free account adds the AI tutor with a monthly allowance, notes and progress. Plus and Pro plans unlock every lesson and larger AI allowances; current prices are on the Plans section.
- How should I prepare for a system design interview?
- Learn the fundamentals first (scaling, consistency, sharding, databases), then the building blocks interviewers expect you to reach for (caches, queues, load balancers, CDNs), then practice complete case studies out loud within a 45-minute structure: requirements, estimates, high-level design, deep dives, trade-offs. Clotiv's System Design track is ordered exactly that way.
- Which system design interview questions are asked most often?
- Across 2026 interview reports the most common prompts are a URL shortener, a rate limiter, a news feed (Twitter), a chat system (WhatsApp) and a video platform (YouTube); AI-first companies now add serving an LLM and designing an AI agent platform. All seven of those case studies are free on Clotiv.
- How do I answer behavioral interview questions?
- Build a small bank of true stories and tell each with the STAR structure — situation, task, action, result — leading with your own actions and a measurable outcome. Clotiv's Behavioral track covers the universal questions, story selection, and the six competencies interviewers score: failure, ambiguity, influence, ownership, leadership and collaboration.
- What is Clotiv's AI Help, and can I trust it?
- AI Help is a chat tutor available on every lesson. Its answers are grounded in the lesson's own text and it can search the web when the answer isn't there. It is an educational aid: it can be wrong, so check its output against the lesson and never treat it as professional or career advice.
- What is a CloToken?
- A CloToken is Clotiv's internal unit for metering AI features. Every plan includes a monthly allowance that resets each billing cycle, shown to you as a percentage used; one-time top-ups add more and do not expire while your account is active. CloTokens have no cash value.
- Does Clotiv offer mock interviews, a question bank or job application tracking?
- Not yet. Mock interviews, a question bank, a live interview helper and job application tracking are on the roadmap and are labelled "Coming soon" on the site; job application tracking will be included with Plus and Pro when it ships. Today Clotiv is the lessons, the AI tutor, notes and progress.
- Do I need an account to read the lessons?
- No. Open lessons can be read signed out. An account (email link, GitHub or LinkedIn) is needed for AI Help, saving notes, tracking progress and for the paid lessons.
Your next loop is closer than you think.
Read the first lesson now — no account needed until you want the AI tutor.