Codility tests engineers in its own VS Code environment, and business roles with short tasks done with its built-in AI Assistant, scored the same way every time. Lemonsignal gives candidates a real task in the AI tool they already use, and records how they worked, with a first read for your team to check.
Can candidates use AI in Codility?
CodilityA Codility AI for Business task: the brief, the built-in AI Assistant and the answer box. Image from codility.com/assess-ai-skills-beyond-engineering, 28 Oct 2026.
LemonsignalThe candidate works in Claude Code here, with the task brief, the time left and Recording on. They can use Codex, Claude Cowork or ChatGPT instead, in the browser or on their own computer.
Codility vs Lemonsignal: side-by-side comparison
What Codility says on its own site, checked 28 Oct 2026, next to Lemonsignal.
What candidates do
Engineering screens and structured interviews in VS Code, with a terminal and multi-file projects. AI for Business: tasks of about 20 to 60 minutes that end in a deliverable, such as a report or an account brief; an assessment can combine several
A real task from the job, such as a bug to fix or a campaign to plan
Which AI tool
A built-in AI Assistant, next to the brief. For live interviews, the interviewer chooses which AI models candidates can use. You can also turn AI off. Their site does not say whether candidates can use their own tools
Their own: Claude Code, Codex, Claude Cowork or ChatGPT, on their own computer or in the browser
Who scores
Business deliverables are scored “deterministically against an expert-defined answer space”, with no generative AI in the grading. Code is analysed automatically for quality and complexity. Their site does not describe a score for how the candidate used AI
Lemonsignal gives a first read, against a scoring sheet written before anyone takes the task. Your team watches the session, checks the read and decides
Roles
Engineering, and eight business functions: customer support, customer success, sales, product management, product marketing, marketing, data analysis and finance
Engineering, product, design, marketing, data and finance
Watching for cheating
Identity verification, impersonation detection and proctoring, with integrity signals given as a risk level for reviewers
Checks the person doing the task is the person you sent it to, and that the work matches the conversation
What you get back
A record per candidate with the deliverable, the score, integrity signals and the full AI Assistant transcript, plus skills data across your engineering team
A recommendation, six AI skills and two or three job skills, each linked to the moment in the conversation it came from
Codility vs Lemonsignal: what the hiring team gets back
CodilityA Codility Screen Report: time spent, a total score, and checks on identity, device and network. Image from codility.com/assess-ai-skills-beyond-engineering, 28 Oct 2026.
Lemonsignal. A result for an engineer who fixed a real bug with Claude Code. Every score links to the moment in the conversation it came from.
LemonsignalDana Okafor
Dana OkaforBackend engineer · Task: Fix a double charge · Claude Code · 2 h 40 min
Checked by Lemonsignal
89%Strong match
Found the cause before letting the AI write a fix.
Tested the AI’s fix instead of trusting it.
Fixed the second service with what she built for the first.
UnderstandStrongHad it reproduce the double charge, and followed one payment through the code before any fix.Turn 2
BriefSolidGave it the logs and the files that matter, and said what it must not change.Turn 4
CheckStrongRan the tests on the AI’s first fix and turned it down. Proved her own fix with a test.Turns 12, 19
CorrectStrongTold it why the first fix was wrong and where to look instead.Turn 13
Sign offSolidA small change with its test, and a note on what she did not test.
ReuseStrongSaved the steps as a skill and used it to fix the refunds service.
Skills for the job
Finding the root causeAbove the bar
Proving a fix with a testAbove the bar
Code others can maintainAt the bar
What she handed in, as she handed it in. Each mark is a skill from her result.
UnderstandStrongSign offSolid
Change noteCharge once per order, even when the gateway retries
Cause: after a gateway timeout, the retry created a second charge.
Fix: each charge carries a key for its order, so a retry returns the first charge instead of making a new one.
Test: a retry after a timeout now charges once. All 48 tests pass.
Not tested: partial captures, which we do not use yet.
CheckStrongReuseStrong
payments/charge.pyThe fix
def create_charge(order, card):
- return gateway.charge(order.total, card)
+ key = f"order-{order.id}"
+ return gateway.charge(order.total, card,
+ idempotency_key=key)
tests/test_charge.pyFails before the fix, passes after
+def test_retry_charges_once(gw, order, card):
+ gw.fail_next_with(Timeout)
+ create_charge(order, card)
+ create_charge(order, card) # the retry
+ assert gw.charges_for(order) == 1
refunds/refund.pyThe same fix in the refunds service
def create_refund(charge, amount):
- return gateway.refund(charge.id, amount)
+ key = f"refund-{charge.id}"
+ return gateway.refund(charge.id, amount,
+ idempotency_key=key)
Should you choose Codility or Lemonsignal?
Choose Codility if
You hire engineers and business roles at volume, and want short tasks scored the same way every time.
You want one platform for screening, interviews and mapping your engineering team’s skills.
You need the checks they list, such as SOC 2, ISO 27001 and WCAG 2.2 AA.
Choose Lemonsignal if
You want candidates in the AI tool they would use in the job, not a built-in assistant.
You want to watch the whole session yourself, and see the moment behind every score.
You want every score linked to the moment in the conversation it came from.
How is Lemonsignal different from Codility’s AI for Business?
Both give business roles a task done with AI. In Codility, candidates use its built-in AI Assistant for 20 to 60 minutes, and the deliverable is scored against an answer space. In Lemonsignal, candidates use their own AI tool on one longer task. Lemonsignal records how they worked and gives a first read. Your team watches the session and decides.
Can we use Codility and Lemonsignal together?
Yes. Some teams screen with short, standard tests and send a real task to the shortlist.
