Comparison. Async coding tests solved throughput. They did not solve signal.
HackerRank, CodeSignal, Codility and the rest are good products that do a real job. Most companies reading this already own one. The question is not whether they work, it is what they can and cannot tell you.
What they are genuinely good at
A comparison page that says the alternative has no strengths reads as dishonest and costs more trust than it wins.
Real strengths
- Genuinely cheap per candidate, and the cheapest way to filter a very large top of funnel
- Zero interviewer time. Nobody has to attend anything
- Objective on the narrow thing they measure: did the code pass the tests
- Mature integrations with every ATS you might use
- Candidates can take them at 11pm, which is a real convenience
Where it stops working
- They score the output and cannot see the reasoning. A candidate who guessed and a candidate who reasoned to the same answer are indistinguishable
- No system design signal worth the name, because design is a conversation
- Nobody can ask "why did you choose that", which is the question that separates levels
- Heavily gamed. The problem sets leak, and the candidates who practice the platform beat the candidates who do the job
- Widely disliked, and the strongest candidates are the ones most able to refuse a two-hour unpaid take-home
Side by side
| Async coding tests | Live | |
|---|---|---|
| What is measured | Whether the code passes | How the answer was reached, and whether it survives follow-ups |
| System design | Essentially none | First class, on a shared whiteboard with a constraint change |
| Follow-up questions | Impossible | The entire mechanism |
| Candidate time | 60 to 120 minutes, unpaid, alone | 25 to 45 minutes, scheduled by them, with a person-shaped conversation |
| Gaming | Practiced problem sets are the main failure mode | Rotating pools, exposure caps, and an interviewer who probes the answer |
| Methodology | Proprietary, unexplained | Published book plus a versioned rubric |
| Cost per interview | $20 to $50 | $16 to $25 at plan rates |
| Engineer time | None | None during, about four minutes reading the report after |
Which one you should actually buy
Not Live, if
You are filtering thousands of applicants and need a cheap first cut before any human judgment is involved. You are hiring for a role where passing tests really is the job. Or you have an established process that works and no complaints about the quality of who reaches your loop.
Live, if
Your engineers are burning hours on first-round conversations. Your hiring managers disagree with each other about the same candidate. You need a system design signal before the onsite. Or you need to be able to hand a regulator, or a candidate’s lawyer, the exact criteria you applied.
These are not mutually exclusivePlenty of teams keep an async platform for high-volume filtering and use Live for the round that decides who reaches an engineer. Live replaces an inconsistent first-round conversation, not your whole funnel.
Judge it on your own interview.
Send an interview to yourself and read your own report.