stonebox

Find your next great engineer.

We run a hackathon built for your team. You hire the winner.

Find your next great hire How it works

Your first 5 candidates are free.

Stonebox · Live leaderboard

Senior ML engineer · hackathon

5 candidates, compared at the same minute

Hour

2:41

  1. 1Maya O.852
  2. 2Sofia R.740
  3. 3Jun P.694

An example hackathon leaderboard: five candidates for a senior ML engineer role, each shown at 2 hours 41 minutes into their own four hours. Maya leads with 852, then Sofia with 740 and Jun with 694.

People who can do your job
Built from your kind of work.
No scheduling, no drop-outs
Candidates start anytime. One live leaderboard.
Nothing to grade
Every submission scored on hidden test data.
AI welcome, no faking it
A 5-minute voice interview checks understanding.

The problem

Coding tests don't show who can do the job.

  • They aced the test. They couldn't ship.
  • The take-homes sit unread.
  • The best candidates drop out.

The only real signal is real work. Now you can see every candidate's.

How it works

Three steps to your next hire.

  1. Role
    Senior backend engineer
    Stack
    TypeScript, Postgres
    Problem
    Orders drop under load
    Scored on
    Orders, speed, accuracy

    1

    We build your hackathon

    From the real work of your role.

  2. Time left

    1:19:07

    Score

    852

    Rank

    1/5

    2

    Candidates compete

    Four hours, any time, any tools.

  3. 1Maya Okafor852
    2Sofia Reyes740
    3Jun Park694

    3

    You hire the winner

    Ranked on hidden test data and a voice interview.

Async

A real race. No scheduling.

Everyone is compared at the same minute of their own four hours.

Scores at hour 2:41 of each person's 4 hours

  • Sofia

    Raced on Sunday

    740Final 812

  • Maya

    Racing now

    852

  • Jun

    Starts Thursday

    Not started yet

Different days. Same minute, same race.

Why Stonebox

Not another coding test.

  • Real work from your role

    Yes

    Coding tests: no · Take-homes: sometimes · AI interviewers: no

  • AI allowed

    Yes

    Coding tests: no · Take-homes: sometimes · AI interviewers: no

  • Graded without your team

    Yes

    Coding tests: yes · Take-homes: no · AI interviewers: yes

  • Checks they understand their code

    Yes

    Coding tests: no · Take-homes: sometimes · AI interviewers: no

  • A race candidates want to win

    Yes

    Coding tests: no · Take-homes: no · AI interviewers: no

Hackathons

Built for your team.

Start from one of ours, or we build yours from scratch.

Try one yourself See what each one measures

What you get

Know who to hire before the first interview.

Senior ML engineer · shortlist

5 candidates · fraud detection hackathon

Example
RankCandidateFinal scoreUnderstanding
1

Maya Okafor

Found the data bug in hour one. Explained every change.

85288
2

Sofia Reyes

Steady and careful. Made it fastest.

74074
3

Jun Park

High score, but couldn't explain their own code.

Had trouble explaining their code		69431
4

Alex Novak

Fixed the crashes. Ran out of time.

54865
5

Dev Kim

Working first version. Missed the main bug.

37158
Final score:
their work on test data they never saw.
Understanding:
how well they explained it, out of 100.

Jun would have passed your coding test. The voice interview caught it.

Get started

Tell us who you're hiring.

Two minutes to set up. Your first 5 candidates are free.

Set up your hackathon

Questions

Will strong candidates spend 4 hours?

Yes. It replaces your coding test and take-home, and it's a race, not homework.

Do they need to be online together?

No. Everyone is compared at the same minute of their own four hours.

Can they use AI?

Yes. The voice interview shows who understands their code.

How fast can we start?

Within a few days. Same day if one of our hackathons fits.

What does it cost?

Your first 5 candidates are free.