sys0 is a system design course from Rakesh K, who the terms name as the founder of Coder's Gyan. The public pages describe a written path plus labs: you read a module, then design a system and put it under load. Checked 2 November 2026. This note did not sign in, did not pay, and did not open a lab canvas.
It is a different thing from Breakscale and GonnaCrash. Those two are simulators you can open in a browser. sys0 is a paid course whose syllabus is mostly still scheduled, and the lesson and lab URLs tried here stopped at a Google login.
What is published
The path page and the homepage both say 19 modules, 137 lessons, 18 labs, about 31 hours, plus 16 system labs. The three part headings add up to that lesson count: Foundations 10 modules and 62 lessons, Distributed systems 8 modules and 56 lessons, Under the hood 1 module and 19 lessons.
On 2 November 2026 the path page had lesson text only for module 1, "What is system design?". Lessons 1.1 and 1.2 are marked Free. Lessons 1.3 and 1.4, and the clinic lab (1.5, listed as 30 minutes), are not. Modules 2 through 19 are headings and one-line plans, with dates from October 2026 through June 2027. Module 2 still said "Rest coming Oct 2026" on this read, after that month had ended. The terms, last updated 14 October 2026, say those dates are a plan, and lessons may be changed, reordered, or rewritten.
The labs index lists 16 product designs. Two are marked Free: a URL shortener (13 steps, about 45 minutes) and a Udemy-like database (14 steps, about 75 minutes). The other 14, including YouTube, Instagram, WhatsApp, Spotify, and a Dynamo-style store, are marked Soon. The page says each system is modelled on a known product and that sys0 is not affiliated with those companies.
Fetching https://sys0.in/path/what-it-means and https://sys0.in/labs/url-shortener without a session returned the same page: "Log in to keep building" and "Continue with Google". The syllabus and the lab list are public. The free lesson and the free lab were not readable from this session. The FAQ says lessons marked Free are open to everyone so you can try the course before paying. That sentence and the login wall are both on the site.
Price and account
The homepage served to this network offered a founding membership, billed yearly, for the first 500 members at 50% less for as long as they stay subscribed. The figures on the page were ₫2,817,051 crossed out, ₫1,408,525 per year, and about ₫117,377 a month. It says the higher figure returns after the first 500 members, and that the founding price lasts until the path is complete. A web-search snippet of the same homepage showed $300 a year and an end date of 30 October 2026. Those strings are not in the HTML fetched here. The privacy policy says the country is inferred from the connection, a cookie remembers it, and prices are shown in that currency. Treat the dong amounts as the price this network was shown on 2 November 2026, not as a worldwide price.
Checkout, the lesson, and the lab all redirected to the Google login when opened logged out. The terms say:
- Sign-in is a Google account, one person per account.
- The membership renews every year until you cancel it from the billing page. Access runs to the end of the year already paid.
- Payments are handled by Dodo Payments. The terms say sys0 does not see card details. The refund page also names card, UPI, and bank account as ways the money can return.
- Founding price stays while the subscription stays active. A lapse or a refund drops it.
The refund policy, also dated 14 October 2026, refunds 97% if you email hello@codersgyan.com within 24 hours of the payment, from the sign-in address. The other 3% is described as the processor fee, which they say is not returned to them either. They say they reply within 2 working days, access ends when the refund is made, and banks usually take 5 to 10 working days. A mistaken double charge, or a failure on their side that blocks access, is a full refund with no 24-hour limit. The terms say the contract follows the laws of India.
The FAQ says a subscriber gets every lesson that is already out and each new one while the subscription lasts, and that three new lessons ship every week. That weekly rate is the FAQ's sentence. The module dates on the path page are the other public schedule.
What the pages say they store
The privacy policy, dated 14 October 2026, lists:
- Name, email, and profile photo from Google.
- Finished lessons, and what you write or design in labs and exercises.
- Whether you have paid, the plan, and its dates. Card or bank details stay with the payment provider.
- Country, from the connection, for the price currency.
- Page visits and actions such as finishing a lesson.
- Waiting-list or support email, if you send one.
Processors named there are Google for sign-in, Dodo Payments for the subscription, PostHog for usage analytics, and OpenAI for review of the text you submit for feedback. The policy says OpenAI gets that answer text and not the account details. Hosting and the database are mentioned and not named. Cookies named in the policy are a sign-in cookie, a country cookie, and analytics cookies. It says they do not sell data and do not use advertising cookies. Account deletion is by email to hello@codersgyan.com, with a stated reply within 7 days, except payment records the law requires them to keep. The policy says the site is not for children under 13.
The terms say some exercises return feedback from an AI model, that the feedback can be wrong, and that it is not professional advice. What you write and design stays yours. The lessons, diagrams, labs, and code stay theirs. The footer links X (https://x.com/sys0HQ), LinkedIn (https://www.linkedin.com/company/sys0), and GitHub (https://github.com/codersgyan). A search of that GitHub account for a repository named sys0 returned no match. The course source was not found in public.
See also: Breakscale · GonnaCrash · Syscraft · System design fundamentals · Designing For Distributed Failure