LeetSys

What it does

Master system design interviews with AI-powered practice sessions. Interactive whiteboard, voice conversations, and real problems from Google, Meta, Amazon. Start practicing today!

Learn system design with guided interactive walkthroughs, live architecture diagrams, and design decisions, then practice in AI-assisted mock interviews.

Follow guided, interactive walkthroughs—then practice the same system in a mock interview with a whiteboard, voice or chat, and focused AI feedback. A focused workspace for prompts, diagrams, conversation, and feedback—without switching tools. Get real-time feedback on your architecture choices from an intelligent interviewer that adapts to your seniority level. Draw system diagrams with an intuitive canvas. Create components, map data flows, and explain your design visually. Practice common interview-style prompts, from URL shorteners to globally distributed social networks. An AI tutor walks you through one system at a time. Watch the architecture take shape, make the decisions that…from leetsys.dev

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  Design Interview Sessions2024 · ▲5

  LeetCode for System Design

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  I couldn't afford interview prep, so I built a free alternativeSep 2026 · learningto.co · ▲41

  Learning to pass the Google interview? Master data structures, algorithms, and system design with interactive visualizations, a code playground, and AI feedback.

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  System Design Practice and Discussion2022 · workat.tech · ▲8

  Many platforms exist for a candidate to practice leetcode style questions. Created one to practice and discuss system design problem statements. There is no auto evaluation as high level design is subjective, but we support upvotes/downvotes and a comment section for feedback and discussion. Looking for early feedback.

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  Mocked2025 · trymocked.com · ▲14

  Hi HN, I launched an AI tool a few months back to help with product management interviews. It's Leetcode-style prep, but you can verbally respond to questions and receive feedback. I originally started it as a side project, but it blew up on Linkedin and we're nearing 5-figure ARR. I would be grateful for some honest feedback and advice on both the growth and engineering side. I'm particularly interested in: - What's one feature you feel is glaringly missing? - How did similar educational consumer apps (7sage, Leetcode) scale beyond just ads? - Should I implement a landing page? I wanted to…

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  I made an AI coach that listens in your interviews and shows answers2024 · milio.ooo · ▲7

  You can use it live during your interview or practice mocks interviews. It can also solve Leetcode and IQ questions on the go. Making online and telephone interviews easy peasy.

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  AI Mock System Design InterviewJan 2026 · systemdesigntrainer.com · ▲8

  Master System Design Interviews Before the Real One

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  /dev/null▲484

  a social network for devs

  Dev tools · 3d ago · dev-null.sh

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  Whiteboard (YC W26) – an open-source IDE for thoughtful software design▲423

  open-source IDE for thoughtful software design. Contribute to devdotfast/whiteboard development by creating an account on GitHub.

  Dev tools · 28d ago · github.com

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  Reladraw – A diagram language where you decide where to place things▲411

  Contribute to reladraw/reladraw development by creating an account on GitHub.

  Dev tools · 26d ago · github.com

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  OpenBot▲362

  Grok Bot alternative: free, local, open-source, multiplayer

  Dev tools · 23d ago · openbot.run

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  Talanoa▲346

  Hi HN, I’m a fullstack developer, and honestly, I’ve lost count of how many side projects I’ve worked on over the years. But one idea kept coming back to me: a different kind of email client. It first came to me in 2014: “What if we could handle emails more like conversations?” Every year, I’d revisit this concept in my “Build Notes.” Ten years later, no one had built exactly what I had in mind — so I finally decided to do it myself. That’s how Talanoa was born. I wanted something focused on people, not timelines. I was tired of marking messages as unread just to remember to reply later, or…

  Dev tools · 21d ago · talanoa.email

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  CoreSpeed▲332

  One MCP for everything your agents need: apps, memory, tools

  Dev tools · 28d ago · corespeed.io

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  Trace▲1,555

  Workflow Automations for the Human 👾 AI Workforce

  AI · 2025 · trace.so

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  I spent 6 years building a ridiculous wooden pixel display▲1,145

  I built the world's most impractical 1000-pixel display and anyone in the world can draw on it. It draws a single pixel at a time and takes 30-60 minutes to complete a single image. Anyone can participate in the project by voting for the next image to be drawn, and submitting images. https://kilopx.com/

  Work · 2025 · benholmen.com

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  Indy AI by Contra▲1,070

  Job boards are dead. Your network is alive

  AI · 2025 · contra.com

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  Kitten TTS – 25MB CPU-Only, Open-Source TTS Model▲1,003

  Kitten TTS is an open-source series of tiny and expressive text-to-speech models for on-device applications. We are excited to launch a preview of our smallest model, which is less than 25 MB. This model has 15M parameters. This release supports English text-to-speech applications in eight voices: four male and four female. The model is quantized to int8 + fp16, and it uses onnx for runtime. The model is designed to run literally anywhere eg. raspberry pi, low-end smartphones, wearables, browsers etc. No GPU required! We're releasing this to give early users a sense of the latency and voices…

  AI · 2025 · github.com

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  I was curious about spherical helix, ended up making this visualization▲865

  I was wondering how I can arrange objects along a spherical helix path, and read some articles on it. I ended up learning about parametric equations again, and make this visualization to document what I learned: https://visualrambling.space/moving-objects-in-3d/ feel free to visit and let me know what you think!

  Life & fun · 2025 · visualrambling.space

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  The current sky at your approximate location, as a CSS gradient▲788

  For HTML Day 2025 [1], I made a web service that displays the current sky at your approximate location as a CSS gradient. Colours are simulated on-demand using atmospheric absorption and scattering coefficients. Updates every minute, without the use of client-side JavaScript. Source code and additional information is available on GitHub: https://github.com/dnlzro/horizon [1] https://html.energy/html-day/2025/index.html

  Dev tools · 2025 · sky.dlazaro.ca