Embedded interview prep for engineers who read the datasheet. AI writes the first draft now. Interviews test the rest: find what it got wrong, fix it, and explain the mechanism. Then answer the follow-up.
Anyone can generate a ring buffer. The interview asks why it drops one byte in ten thousand at 921600 baud.
What you get
Memorised answers survive one question. Interviews go three deep. Every exercise here makes you explain the mechanism.
Firmware with planted bugs. Flag the lines and say what breaks. Then fix it and build it with clang against a mock Cortex-M target.
Bits, arrays, strings, memory, lists and checksums. Write it, run it, see which test failed and what it expected. clang runs in your browser.
What each company's embedded teams hire for, how the rounds usually run, and the challenges that match.
After each challenge the interviewer asks the next question, then the one after. Every answer gets PASS, PARTIAL or FAULT, with the reason.
Five questions a day on C, Cortex-M and RTOS. Expect integer promotion. Interviewers do.
Every submission is logged, with accuracy by track. Sign in and it syncs across devices.
How it works
The three things an interviewer checks. About ten minutes a challenge.
Read code an AI assistant wrote. Flag every line you'd stop in a review.
Edit it and build it with clang. Quick checks catch the common misses. The reviewer judges the logic.
The interviewer asks the follow-up a senior engineer would. Then it grades the answer.
AI interviewer
Prepared answers cover the first question. The second and third ask for trade-offs, out loud. That is where the decision gets made.
Coverage
Pick a company you're targeting and get a playlist of challenges, their usual rounds and a question bank.
HeapCrash is not affiliated with or endorsed by these companies. Prep is based on their public job descriptions and product information; practice questions are original.
Pricing
Every challenge is free. Pro buys more AI interviewer time for the weeks before your interviews.
Everything you need to start.
Cancel any time. Pro stays on until the end of the month you paid for.
FAQ
Not to read. Bug hunts, Fix-it quick checks, company guides and the daily quiz work without one. Running code and the AI interviewer need a free Google sign-in. So does syncing progress.
C everywhere. C++17 in Basics, because product companies use it on larger parts. Python for the validation track, because test rigs run on it. The compiler is clang 21 built for WebAssembly. It runs in your browser, so your code never leaves your machine.
Final-year students and working engineers preparing for embedded software, firmware, and embedded validation roles. Most of the content assumes you know C.
One follow-up interview after a challenge, one company mock round, the AI reviews of one challenge's fixes in a month, or (Pro) the AI error explanations for one problem in a month. Allowances reset on the 1st of each month.
No. Questions are original, written to match the skills in each company's public job descriptions. Users can mark questions they were asked, which helps others see what's common.
From your account menu, any time. You won't be charged again, and Pro stays active until the end of the month you've paid for. See the refund policy.
Start with the UART ring buffer. It has four bugs. How many can you find?
Find the bugs