Interview mode: HardCoding · System design · Behavioral · Negotiation
The interviewis the boss fight.
Add your CV, paste a job link. Hardmode builds that role’s interview loop and runs every round with an AI interviewer who has read both. No passive prep. Just reps.
[ System status: ready when you are · 20 free credits on sign-up ]
// 01 — The simulator
It doesn’t just ask the question. It asks the next one.
- 00:42INTERVIEWER
“Your CV mentions the API gateway you built at your last job. Let’s go further: design a rate limiter that works across multiple servers.”
- 01:15YOU
“I’d probably start with a token bucket algorithm—”
- 01:31INTERVIEWERFollow-up
“Okay. What happens when two servers receive requests for the same user at the same time?”
- 01:38YOUThinking out loud
1algo : token bucket2key : user_id3limit : 100 req / min4state : ???5sync : ???6// shared state across nodes?
- What went well
- Focus areas
- Try this
// 02 — How it works
From job link to interview loop.
- 01
Add your CV, paste the job
Upload your CV once (optional), then drop in a job posting URL or paste the description.
- 02
We read both
Hardmode parses the posting in the background (role, level, stack, and hints about the process) and compares it with your CV.
- 03
Get your loop
A realistic interview plan for that job, with what each round is likely to probe given your background. Add, drop, or reorder rounds. The plan is free.
- 04
Pick a difficulty, run the rounds
Easy, Medium, or Hard. The AI interviewer knows your CV and asks about your actual career. Retry as often as you like.
- 05
Get feedback, then rerun
Detailed, supportive feedback after every session: what went well, what to work on, and how. No scores. Download the recording to rewatch.
$ read jobs.example.com/senior-backend
fetching posting parsed · comparing with cv
- role
- senior backend engineer
- domain
- payments
- stack
- go · postgres · kafka
- signals
- “design for scale” · “on-call”
- your cv
- 5 yrs · python · aws · no kafka
- 01Intro screenwhy payments, why now15–20 min10 cr
- 02Live codinggo · concurrency45 min25 cr
- 03System designidempotent payment ledger45–60 min30 cr
- 04Technicalkafka · not on your cv, expect it45 min20 cr
- 05Behavioralyour billing migration story30–45 min20 cr
- 06Negotiationthe offer call15–20 min10 cr
// 03 — Every round in the loop
Eight rounds.
One loop.
Practise the full loop for a job, or pick any single round on its own. No job description needed.
- 15–20 minIntro & recruiter screenThe first call. Tell your story, explain why this role, and handle the logistics questions without fumbling.10 credits
- 45 minQuestion bankLive codingAlgorithms and data structures in an in-browser editor, while you explain your approach out loud.25 credits
- Build asyncQuestion bankTake-home assessmentBuild a realistic assignment on your own time, then defend your decisions in a live review.25 credits
- 45 minTechnical interviewFundamentals, past projects, and debugging. How deep your understanding actually goes.20 credits
- 45–60 minQuestion bankSystem designDesign a system at scale, sketch it on the scratchpad, and defend every tradeoff.30 credits
- 30–45 minLeadership & behavioralConflict, ownership, failure, and influence. Real stories, structured well, that survive follow-up.20 credits
- 30–45 minProduct senseFor product-minded engineers: who the user is, what to build first, and how you’d know it worked.20 credits
- 15–20 minSalary negotiationThe final boss. Rehearse the offer call: anchoring, counter-offers, and asking for more without flinching.10 credits
// 04 — Difficulty
Choose your
difficulty.
Warm up on Easy, rehearse on Medium, and switch to Hard when you want the full boss fight.
- Warm-up
Easy
A friendly interviewer who wants you to do well.
- + Encouraging and patient
- + Hints when you’re stuck
- + Time to think
- + Gentle follow-ups
Best for a first attempt, warming up, or getting your confidence back.
- RealisticDefault
Medium
A fair, professional interviewer. What most interviews feel like.
- + Real follow-up questions
- + The occasional nudge
- + Normal pacing
- + Expects you to drive
Best for regular practice and rehearsing for a specific loop.
- Bar-raiser
Hard.
A proper grilling, like a big-tech bar-raiser loop.
- + Relentless follow-ups
- + Every assumption challenged
- + Constraints change mid-answer
- + Few hints, tight clock
Best for the week before the real thing, or proving to yourself you’re ready.
Same credits at every level · Feedback is just as supportive on Hard
// 05 — Questions
Our questions. Or yours.
A curated bank for the rounds where the problem matters most, matched to the level and stack of the job. Got a question from a past loop, or one a friend was asked? Paste it and run it as a full round.
bank/curated
From the question bank
Problems picked for the role, with follow-ups that change the constraints once you have a working answer.
bank/custom
Bring your own question
Works for live coding, take-home briefs, and system design. The interviewer treats it like any other round: clarifications, follow-ups, and a review at the end.
// 06 — Feedback & progress
Feedback, not a verdict.
Every interview ends with detailed feedback: what went well, what to work on, and how. No scores, no pass or fail. The point is to get better, not to feel graded.
- What went well
- You asked about traffic before drawing anything, and used the estimate to justify a cache-first read path.
- Focus area
- Shared state across nodes. This is where the design paused when the follow-up came. Practise naming two options and their tradeoffs before choosing.
- Try this
- “I see two options: a central store like Redis, or sticky routing per user. Redis is simpler to reason about; the cost is an extra network hop…”
- Next step
- Try the same round on Medium, with a different distributed-state problem.
Highest difficulty completed
- Intro screenHard
- Live codingMedium
- System designMedium
- BehavioralEasy
- NegotiationNot yet
Focus areas
- Clarify requirements before codingImproving
- Shared state in distributed designsPractising
- Say “I”, not just “we”, in storiesNew
Your dashboard tracks the rounds you’ve covered, the difficulty you’ve reached, and the focus areas that keep coming up, until they stop. Credits never expire, so take a break after your search and pick up where you left off next time.
// 07 — Switch seats
Watch the boss fight.
Take the interviewer’s chair. The AI plays the best candidate for the job you pasted and shows you how they work through the problem, while asking the questions you should be asking. Watch, or steer it with your own follow-ups.
Clarify first
Requirements and constraints before a single box is drawn.
Show the math
Estimates said out loud, and used to justify choices.
Name the tradeoff
What each decision costs, not just what it buys.
Ask good questions
The questions a strong candidate asks the interviewer.
- 00:12You
“Let’s design a URL shortener.”
- 00:20CandidateClarifying
“Before I draw anything: is this public, and roughly how many redirects a day are we expecting?”
- 00:31You
“Public. Say a hundred million redirects a day.”
- 00:44CandidateEstimating
“That’s around twelve hundred reads a second on average, so the redirect path should be cache-first. Writes are rare by comparison. I’ll keep them simple and spend my time on reads.”
- 01:10CandidateAsking you
“Is it acceptable if a new link takes a second or two to work everywhere, or does it need to be instant?”
// 08 — The mission
You don’t get better by reading answers.
You get better by thinking out loud, defending your decisions, getting stuck, and learning to recover. Hardmode is built around the part of interview prep that actually matters: practice under pressure.
01 —
Think out loud
Practice explaining your reasoning, not just producing the right answer.
02 —
Pushback, at your pace
Follow-up questions that challenge your assumptions, from friendly on Easy to relentless on Hard.
03 —
Get better every run
Every session ends with detailed, supportive feedback and a clear next step. No scores, no verdicts.
// 09 — Pricing
Pay per rep.
Every round costs credits, at any difficulty. Buy a pack when you need it, or subscribe while you’re searching. Credits never expire, so take a break and come back for your next search.
- On sign-up
- 20free credits
- Typical full loop
- ~95credits
Credit packsOne-time
- Starter100 credits$12
- Loop300 credits$29
- Offer Season800 credits$69
MonthlyCancel anytime
- Practice250 credits$19/mo
- Hardmode700 credits$45/mo
USD · Taxes calculated at checkout
Compare plans and credit costs// 10 — FAQ
Questions.
Who is Hardmode for?
Do I need to upload my CV?
What’s the difference between Easy, Medium, and Hard?
Will I get a score?
Do I need a job description?
What if the job posting is behind a login?
Does Hardmode know the actual questions a company asks?
Is the interviewer a person?
Can I retry a round?
Do I speak or type?
Can I rewatch my sessions?
How much does it cost?
What happens to my CV, recordings, and code?
// 11 — Player 1
Get ready for hard mode.
Paste the job you want. Run the loop until the real one feels like a rematch.
20 free credits · No card required