React · Vue · Angular · Node · Python · Go · QA · DevOps · Game dev

Assess judgment,
not syntax.

AI can write the take-home now, so we stopped grading the artifact. Candidates work in live sandboxes on genuinely broken systems — copilots allowed — and what gets measured is the judgment around the code: what they fixed, what they distrusted, and how they verified what a model wrote for them.

From $399/month · Invoiced, not charged · Live in a working day

No webcams · No lockdown browser · No keystroke logging — ever

running
src/ledger/transfer.tsRace condition
async function transfer(from, to, amount) {
const balance = await db.balanceOf(from);
if (balance < amount) throw new InsufficientFunds();
await db.debit(from, amount);
await db.credit(to, amount);
}

The catalogue

Exactly what you can dispatch, before you ask for access.

10 calibrated tracks, 26 ready-to-dispatch challenges — every one proven against a deliberately flawed baseline and a reference solution before any candidate sees it. No guesswork, no “contact us to find out”: if it is not on this list, we do not sell it as ready.

React / TypeScript

4 challenges
ReactTypeScriptVite

junior → senior · calibrated

Vue 3

1 challenge
Vue 3Composition APIVite

junior · calibrated

Angular

3 challenges
AngularRxJSTypeScript

junior → senior · calibrated

Node.js services

3 challenges
Node.jsTypeScriptExpress

junior → senior · calibrated

Python backend

1 challenge
Python 3.12FastAPIpytest

mid · calibrated

Go services

1 challenge
Go 1.24net/httpgo test

mid · calibrated

QA Automation

5 challenges
PlaywrightTypeScript

junior → senior · calibrated

Manual & Exploratory QA

4 challenges
Test designRepro reports

junior → senior · calibrated

DevOps / CI

3 challenges
DockerGitHub ActionsCI caching

mid → senior · calibrated

Game development

1 challenge
PhaserCanvasTypeScript

senior · calibrated

In the pipeline — labelled honestly

  • Java / Spring Bootnext in line — warm-start loop proven at ~1.2s on live E2B
  • .NET / C#planned — warm-start loop proven at ~2.1s on live E2B, follows Java

Scale tier · engineered for you

Your stack. Your failure modes. Calibrated like everything else we ship.

The public library tells you someone can engineer. Only your own domain tells you they can engineer here. A Custom Calibrated Track is a genuinely broken system that looks like yours — your framework versions, your architecture’s sharp edges, the incident your seniors still talk about — rebuilt by our engineers as a timed, gradable challenge. And it goes through the same harness as every public track: a flawed baseline that predictably fails, a reference solution that scores 100%, proven on live cloud sandboxes before your first candidate sees it.

Exclusive to your workspace

Enforced by a database policy, not a promise. No other customer can see it, dispatch it, or know it exists.

You give us an hour

One scoping call with a tech lead; a sealed, calibrated track in your dashboard in about two weeks. We author, you inform.

Candidates meet your real work

The honest job preview generic quizzes cannot give — and a signal AI assistance does not wash out, because the failure is contextual.

Request a track consultation

Ruby, Rust, C++, or something stranger — the harness that calibrated the ten public tracks points wherever you hire.

The case

Your senior engineers are the most expensive part of your funnel.

A first-round technical screen costs an hour of someone who could be shipping, plus the context switch on either side of it. Most of that hour confirms what a well-built exercise would have told you before anyone joined a call.

So the funnel filters progressively. Everyone gets a ten-minute fundamentals task, auto-graded, no human in the loop. Only the people who pass reach a deep dive, and only those reach your tech lead — who opens one view holding the code, the grader report and the recruiter’s notes.

Worked example

Applicants per opening
40
Filtered by the 10-minute screen
~65%
Senior engineer time per deep dive
75 min

Engineering hours returned

~30/month

26 of 40 filtered before a tech lead opens anything; 14 deep dives × 75 min ≈ 32 hours returned. Substitute your own numbers — the shape is the point, not our arithmetic. At $399 a month, break-even is under three of those hours at a loaded senior rate; the other twenty-nine are the product.

The pipeline

Every stage removes people the next stage would have wasted time on.

Every track in the catalogue runs the same shape of funnel with different tasks in it. The point is not the tasks — it is that nobody expensive looks at anybody until something cheaper has already said they are worth it.

  1. 01Recruiter

    Open the position, screen, dispatch

    Everything starts from a position. Your recruiter opens one, adds candidates into it, reviews fit with the CV and notes attached, and dispatches the assessment from there. They never see code — that boundary is a database policy, not a hidden button.

    No engineering time

  2. 02Calibrated

    The challenge is fitted, not picked

    Routing reads the CV and the role: stack, seniority, domain. Every underlying challenge was proven against a flawed baseline and a reference solution before any candidate saw it — the wording adapts to the person, the bar never moves.

    Stack · profile · seniority

  3. 03Automated

    A live sandbox, graded twice over

    A ten-minute screen filters the field; survivors get a 45–55 minute deep dive in a genuinely broken repo. A hidden suite scores correctness; the weighted rubric scores the craft — what they fixed, and how.

    Correctness + craftsmanship

  4. 04AI-drafted

    The interview guide

    After submitting, the candidate can write a short debrief — next steps, doubts, where AI helped and how they checked it. A model reads the diff and those words, and drafts questions for your tech lead, anchored to file and line. Never a score, never a recommendation.

    From the real diff

  5. 05Tech lead

    A person decides

    The diff, the grader report, the guide and the recruiter’s notes in one view. Your lead reads, asks, and makes the call — no candidate is ever subject to a decision made solely by software.

    GDPR Art. 22 · human decision

The moat

Everything a candidate touches is real infrastructure.

Not a code box that shells out to an evaluator. A container, a database with its own isolation boundary, and a grader that reports structured evidence rather than whatever landed on stdout — because judgment can only be measured against systems real enough to have judgment about.

Execution

Real Docker containers

Every attempt boots a genuine sandbox with a filesystem, a package manager and a network. Candidates run the suite, read the failure, and iterate the way they would on a Monday — because a challenge that cannot be run is a quiz about code, not a test of engineering.

CANDIDATE SANDBOXGRADER SANDBOXsrc/tests/visible.spec.tspackage.jsongit bundle (their diff)grader-report@1tests/hidden.spec.tsdiff onlyhidden suite mounted here, never there
The candidate’s diff travels to the grader. The hidden suite never travels the other way.

Isolation

Row-level security

Every tenant’s data is separated by Postgres policies, forced on every table, with no application role able to bypass them.

alter table assessments
  force row level security;

create policy tenant_scope
  on assessments
  using (tenant_id
    = app.current_tenant_id());

The Debrief

Three questions after the timer stops

When they submit, the pressure ends and the signal starts: what would you do next, what do you trust least, where did AI help and how did you check it. Voluntary, five minutes, verbatim to your reviewer — the asynchronous version of the best moment of pair programming. Their own words become the opening questions of the interview, which is why bluffing them is pointless.

Our stance

No spyware. AI allowed.

No webcams, no lockdown browsers, no keystroke logging — surveillance selects for candidates with no alternatives, which is the opposite of the pool you are paying to reach. Copilots are permitted, disclosed, and discussed: we evaluate how an engineer verifies what a model writes, because that is the job now.

After grading

The interview, pre-drafted

Hidden suites and a weighted rubric decide the score. A model then reads the diff the candidate wrote — and their own post-submit debrief — and drafts three or four questions for your tech lead, each anchored to a file and line. Questions — never a score, never a recommendation.

Routing

The CV picks the track

A model extracts a skill vector. Arithmetic — not the model — selects from your verified library, so the same seniority always draws comparable work.

Integrity

Advisory, never automatic

Paste bursts and focus loss are recorded and shown as context. They never move a score on their own, because a signal that silently fails someone is one you cannot defend in an appeal.

Three views

One pipeline. Three readers. Zero forwarded spreadsheets.

A hiring decision is shared by three people who have always been shown one interface built for none of them. Every Arbiter seat opens onto a view built for exactly its reader — and deliberately no fourth step: your tech lead decides, your executive is briefed, and nobody waits on a second sign-off.

Recruiters

Operate the pipeline, never the code

Open a position, add candidates, dispatch, track the funnel. Source code is invisible to this seat — enforced by database policy, so calling the API directly returns exactly what the screen shows.

Foolproof by construction

Tech leads

Pure signal, in reading order

The rubric, the diff, the candidate’s own debrief, then AI-drafted questions anchored to file and line. Human evidence always outranks generated prose — the machine asks, it never concludes.

Fifteen minutes to a confident interview

Executives

The Decision Brief

Band, score, criteria passed, time used, and the tech lead’s read — every sentence assembled from structured facts. No model writes your executive summary, so nothing in it can be hallucinated.

Informed, never bottlenecked

The difference

Inverting a binary tree does not tell you whether someone can debug a production incident.

Algorithmic screens are not useless — they measure a real skill. They simply measure a different job than the one you are hiring for. The work you are actually buying is reading unfamiliar code, distrusting a green checkmark, and finding the failure mode nobody wrote a test for.

A puzzle screen asks

  • Can you recall the right data structure under time pressure?
  • Can you write a correct function from a complete specification?
  • Can you optimise something you were told is slow?

An Arbiter sandbox asks

  • Can you find the defect the existing suite does not catch?
  • Can you tell a flaky test from a real race condition?
  • Can you work out intended behaviour when nobody wrote it down?

A green checkmark is one axis. Your engineers review on two.

Every criterion in a rubric is authored as either correctness — does it observably work — or craft — how it is built: the cleanup function, the cache key that can hit, the structure a senior flags in PR review after CI is green. Two subtotals from the same graded criteria, pure arithmetic, no model opinion anywhere.

Because “the tests pass and the code is a liability” and “one test fails and the architecture is exactly right” are opposite hiring conversations — and a single score cannot tell you which one you are about to have.

Sound approach, flawed execution

craft ✓ · correctness ✗

Correct, and built to last

both axes clear

Neither axis cleared

the rubric says why

Works, but brittle

correctness ✓ · craft ✗

The obvious question

“Why not just paste their code into ChatGPT?”

You can. It costs nothing, takes a minute, and returns a confident paragraph. Here is what you would actually be running — four failures, any one of which is enough:

I

You would be grading their model, not them

Their copilot co-wrote the artifact — pasting it into a chat measures frontier model capability with a human’s name attached. Signal now lives in what AI assistance does not erase: behaviour in a live broken system, the verification story, the debrief in their own words.

II

A 7/10 with no instrument behind it

Ask twice, get a 6 and an 8 — against no baseline, predicting nothing. LLM judges carry documented biases: sycophancy, verbosity preference, and self-preference — they rate model-written code more highly, which is exactly what candidates now submit. Every Arbiter score comes from a challenge proven to fail a flawed baseline and pass a reference solution.

III

A regulated act, performed in a consumer app

An AI system that evaluates candidates is an AEDT under NYC Local Law 144 — bias audit, notice — and high-risk under the EU AI Act’s employment annex; a solely automated rejection violates GDPR Article 22. The chat-window version has none of that, and the candidate’s code and CV now sit in a consumer tool’s history with no data processing agreement.

IV

“The chatbot said no” is your appeal record

A rejected candidate, an auditor, or a court asks why. Our answer is a signed grader report, a calibrated rubric, a process record, and a named human’s decision. The shortcut’s answer is a chat transcript.

And the part that surprises people

We run frontier models all through Arbiter — reading the CV to route a challenge, personalising the task to a candidate’s background, drafting the interview questions from their real diff. For judgment, never. That is not a capability we lack; it is the product. A chat window is not our competitor — it is a component, and a component does not come with a calibration harness, a disclosure architecture, or someone to hold liable.

Access control

Your recruiters do not need to read source code.

So they cannot. Enforced by row-level policies in the database, not by hiding buttons — a recruiter who calls the API directly gets exactly what the interface gives them.

Admin

Manage billing, workspace settings and members. Full access to candidate work.

Interviewer

Read submitted code, grader reports and rubric detail. Can overrule a grade.

Recruiter

Send and revoke assessment links, and see pass or fail. No access to code.

Pricing

The price is on the page.

One flat rate a tech lead can approve alone — priced for adopting this quarter, not for a procurement cycle. The rigour is not discounted with it: every workspace still begins with a challenge calibrated against your stack, proven against a flawed baseline and a reference solution until it separates them. That hour of our time is in the price, not behind a quote.

Billing period

Growth

Start here

One hiring team, calibrated challenges, invoiced.

$399/month, invoiced

or $3,990/year with two months free

Up to 25 seats

  • 100 assessments a month included
  • Ten calibrated tracks — React, Vue, Angular, Node, Python, Go, QA automation, manual QA, DevOps, game dev
  • Live cloud sandboxes with real containers
  • Challenges calibrated against your stack before you send one
  • Contextual flavouring from the CV
  • Admin, interviewer and recruiter roles
  • AI interview guide generated from the code they wrote
  • Integrity signals and a full audit log
Request access

Scale

Several openings in flight, and a stack of your own.

$699/month, invoiced

or $6,990/year with two months free

Up to 60 seats

  • Everything in Growth
  • 150 assessments a month included
  • One custom challenge track a year, engineered and calibrated for your stack
Request access

Enterprise

For regulated hiring and central procurement.

Talk to us

Unlimited seats

  • Everything in Scale
  • Volume pricing past 150 assessments a month
  • Custom challenge tracks, engineered and calibrated for your stack
  • Data Processing Agreement and security review
  • Custom CV and code retention windows
  • Candidate disclosure records exportable for NYC LL144
  • Annual invoicing and purchase orders
  • Named contact for candidate data requests
Request access

Asked for, not yet built

  • Java / Spring Boot track
  • Greenhouse, Lever and Ashby sync
  • SAML SSO and SCIM provisioning
  • EU data residency
  • Scheduled bias audits

Listed because you will ask, and because a feature list that quietly includes them would be one you could hold us to. Tell us which of these you need and we will tell you when — or that we will not.

Give your engineers their afternoons back.

Tell us what you are hiring for. We will have a calibrated challenge and a working workspace in front of you inside a week.

Request access