Practice on your own
A solo run: no candidate link, no consent, straight into the board with the clock and the reveals. It scores against your rubric so a month of practice becomes a progression.
Diagraw Interviews
The whole round, not just the whiteboard
One board, two roles, one clock the server owns. You get the phase plan, the prompt you reveal in pieces and a private lane for notes and scores. They get the board, the statement and the time left. It ends in a report you can read six weeks later.
No card to start. Your candidate joins from a link, without an account and with nothing to install.
Pick the problem, or write your own
No inventing the question five minutes beforehand. The bank ships ten system design prompts from junior to staff, each with the facts you hold back and the concepts you expect to hear. If none of them is your problem, write yours with its own reveals and the interview runs identically.
- Ten prompts, three open on the free plan
- Levelled, in your language, and each one lists the concepts a good answer tends to reach.
- Your own statement
- Title, problem and the reveals you want to drop later. Free accounts get one a month; Pro is unlimited.
- A rubric your team already agreed on
- Your axes and their weights, versioned. Comparing two candidates across two versions is refused rather than averaged.
- A phase plan you can change
- Four by default. On the free plan a longer plan is scaled down to fit the 30 minutes instead of being rejected.
Four links, four different amounts of access
Creating an interview mints one board and four secrets. The link decides the role before the connection is registered, so nobody is one query parameter away from the wrong half of the room.
- The candidate needs no account
- They open the link, give a name and land in a waiting room with a connection check.
- Consent before the board opens
- They read what is kept and answer. The answer is recorded with the version of the text they agreed to.
- Observers are announced
- Up to five on Pro. Everyone in the room sees they are there, the candidate included.
- A report link you can share
- It carries the scored report without your private notes, so it can go to a hiring panel as it is.
The two people in the room see different things
This asymmetry is the feature. Everything the candidate must not see is built per role on the server: their frame is assembled without your notes, your rubric, the phase plan and the reveals you have not dropped yet. It is not filtered afterwards, so a filtering slip cannot leak it.
You run the round
Everything you need, none of it reaching the other side.
- Advance the phase when you are ready, not when a timer says so.
- Reveal the load figures once the design is on the board. Every reveal is timestamped.
- Mark the minute they proposed sharding, and score an axis while it is fresh.
- Pause. The clock stops and so does the board, because a pause used to be free drawing time.
They design
The board, the problem, and how long is left.
- Six tools, no menus: box, arrow, text, database, queue, cache.
- The current phase and its remaining time. Not your plan, not the total.
- The statement as it stands, growing as you reveal.
- Their own copy of the diagram at the end, with no note or score attached.
A dropped connection should not cost anybody a phase
Laptops die and wifi drops. When the person being evaluated disappears, twenty-five seconds of grace absorb the tunnel and then the clock stops and the board freezes with it. When they come back, both start again — and only if the pause was automatic, because one you asked for is yours to undo.
- You can close the tab and come back
- An interview that is still open keeps a way back in from your list. It used to be lost with the tab.
- Nothing stays open forever
- A room that was never used is cancelled and stops counting against your month; one that ran is closed with what it captured.
- Activity signals, in the open
- The board records when the tab loses focus, when a large paste lands, and when a stretch of diagram appears at once. It goes to you, and only to you.
The candidate is told this runs. The consent notice they answer before the board opens names it: window changes, copying and pasting. They do not get a live read-out, because a real-time warning is a training aid for whoever wanted to game it.
Every one of these signals has an innocent reading — reading the statement in another tab looks exactly like reading an answer in another tab. They are something to ask about, never something that scores. And they are not a lock: anyone determined can stop a browser from reporting them.
A report you can still read six weeks later
You close with a verdict and a line of summary. What lands is the scored rubric, the notes at the minute you wrote them, the moments you marked, and what the finished board ended up covering against what the prompt expected.
- Markdown, PDF or the link
- Copy it into your ATS, download it, or send the report link to the panel.
- Compare candidates on one prompt
- Side by side on the same axes. Across two rubric versions it says so instead of averaging them.
- Retention you choose
- The session is purged on the window you set, and the candidate can ask for deletion from the report itself.
Replay the session, not a screenshot of the end
Every accepted change to the board is appended to a log while the interview runs. The first entry is the board as the candidate found it, so the player rebuilds the session forwards rather than reconstructing it backwards from the final picture.
- Watch the order they built it in
- Whether the data model came before the caching layer tells you more than the finished diagram does.
- Jump to a marked moment
- Phase changes, reveals and the moments you marked are ticks on the scrubber.
- Settle a disagreement
- When two interviewers remember the round differently, the log is what actually happened.
Not only for hiring
The same session machinery, pointed at three different jobs.
A class of thirty
One prompt, one board per student. The room a student walks into is the same one a candidate would, and you can walk the grid from your own view of each.
A team that shares a rubric
Members share the prompts, the rubric and the retention window. Suspending someone frees their seat and keeps their history.
What it costs
Free is a real plan, not a trial. Interviewing is bursty by nature, so a seat you are not using can be freed.
Free
0 €- Two interviews a month
- Up to 30 minutes each
- Three of the ten prompts
- One written statement a month
- The full report and the replay
Pro
6 € / month, or 60 € a year- Unlimited interviews
- Up to 3 hours each
- All ten prompts
- Unlimited written statements
- Up to five observers
Team
19 € / interviewer a month- From three seats
- A shared rubric and prompt bank
- A retention window for the whole team
- Suspending a member frees their seat
- 190 € a year per seat
Prices include the plan for the whole product, not only the interview feature. Cancel any time; payment is handled by Paddle.
Frequently asked questions
Does my candidate need an account?
No. They open the link you send, type a name and they are in. There is nothing to install and no signup, which is deliberate: the first three minutes of a round should not be spent on a login form.
Can I use my own problem instead of one from the bank?
Yes. Write the title, the statement and the facts you want to reveal later, and the interview runs exactly as it does with a bank prompt. Free accounts can write one a month; Pro is unlimited.
What exactly does the candidate not see?
Your notes, your rubric and its scores, the phase plan, the reveals you have not dropped yet, the verdict, and the activity signals. Their frame is built on the server without those fields rather than filtered afterwards, so it cannot leak through a mistake in the client.
Is the candidate told they are being recorded?
Yes, before the board opens. They read what is kept and answer, and their answer is stored with the version of the text they agreed to. The notice also names the activity signals: window changes, copying and pasting. What they do not get is a live warning while it happens.
Do the activity signals decide anything?
No, and nothing in the product turns them into a number. Each one has an innocent reading, so they exist to be asked about. They are also not a barrier: a determined person can stop their browser from reporting them, which is why we would rather tell you what they are worth than oversell them.
What happens if somebody's connection drops?
Twenty-five seconds of grace, so a reload costs nothing. Past that, if the person being evaluated is still gone, the clock stops and the board freezes with it, and both restart when they come back. If it was you who dropped, your candidate keeps designing and the clock keeps running.
How long is a session kept?
For the retention window you choose. After that the board, the notes and the replay are purged. The candidate can ask for deletion from the report itself, and an interview nobody ever opened is cancelled rather than kept.
Can somebody watch without taking part?
Yes, with the observer link, and up to five of them on Pro. They can read the private lane but cannot draw, and everyone in the room is told they are there — the candidate included.
Can I use it for teaching rather than hiring?
Yes. A class opens one board per student on the same prompt, and each of those boards is an ordinary interview, so the room a student enters is the room a candidate would. There is also a solo practice mode with no candidate and no consent step.
Is it really free to start?
Yes. Two interviews a month of up to thirty minutes, three of the ten prompts and the full report and replay, with no card. Pro raises the caps at 6 € a month.
Run one this afternoon
Open a board, pick a prompt and send the link. The first interview takes about a minute to set up, and you can practise on your own first if you would rather not learn on a candidate.
Start an interview free