The matching model · explained
Personality-based friend matching — the Big Five, not vibes.
Every other friendship app matches on photos, prompts, and a 12-item personality quiz. Friends? scores you on a validated 120-item Big Five instrument, produces a 30-facet vector, and ranks your entire community against it — then lets the AI plan the first hang.
What we use
The IPIP-NEO-120 instrument
IPIP-NEO-120 is a public-domain Big Five personality instrument. 120 items. 30 facets. 5 Big Five domains. Developed by psychologist Lewis R. Goldberg over decades as an open-science alternative to the copyrighted NEO-PI-R. It's the gold standard for cheap, research-grade personality scoring.
When you sign up, you answer all 120 items. It takes roughly 15 minutes. We don't score any facet from fewer than 4 items (so your profile isn't overfit to a stray answer). We never delete the raw responses — you can reshoot or refine them later.
The five domains
Openness · Conscientiousness · Extraversion · Agreeableness · Neuroticism
- Openness — how much you lean into new ideas, art, novelty. Facets include Imagination, Artistic Interests, Emotionality, Adventurousness, Intellect, Liberalism.
- Conscientiousness — your orderliness, discipline, follow-through. Facets: Self-Efficacy, Orderliness, Dutifulness, Achievement-Striving, Self-Discipline, Cautiousness.
- Extraversion — how you draw energy and what pace of social life fits. Facets: Friendliness, Gregariousness, Assertiveness, Activity Level, Excitement-Seeking, Cheerfulness.
- Agreeableness — warmth, trust, cooperation. Facets: Trust, Morality, Altruism, Cooperation, Modesty, Sympathy.
- Neuroticism — emotional volatility and how you handle stress. Facets: Anxiety, Anger, Depression, Self-Consciousness, Immoderation, Vulnerability.
How we match
Facet-vector similarity — not domain averages.
Most apps that claim "personality matching" compare two people on the five domain scores. That throws away 95% of the signal. Two people can both score 60 on Extraversion while being totally incompatible — one is high on Assertiveness and low on Cheerfulness, the other is the reverse.
Friends? ranks on the full 30-facet vector. Your compatibility with another member is the weighted cosine similarity across all 30 facets, plus a shared-interest boost, plus a proximity boost. The result is a Match Score 0–100 that you see on every candidate card.
The AI planner
Matching is half the job.
Even a perfect personality match dies if neither of you can think of what to do together. So the Friend? AI companion (running on Cerebras qwen-3-235b with a Groq llama-3.3-70b fallback and Anthropic Claude as final safety net) uses your facet overlap to propose three candidate hangs the moment you match. Real venues, real times, two conversation starters. Open the DM already knowing what the first coffee looks like.
Related reading: The Big Five traits, applied to friendship · How the whole app works.
Frequently asked
Is IPIP-NEO actually research-validated?
Yes. IPIP-NEO-120 is backed by hundreds of peer-reviewed studies and is a staple in personality psychology. It's a compressed version of the IPIP-NEO-300, optimized for predictive validity at a quarter the length.
Do I have to take the full 120-item test?
Yes. We intentionally don't let users skip it — a 20-item version produces too much noise per facet to rank on. 15 minutes once per account, in exchange for a profile that actually ranks compatibility.
Can I see my own results?
Yes — your full 30-facet report is on your profile page. Domain averages, facet percentiles, and an explanation of each trait.
Is similar always better for friendship?
Not across every facet. We weight some facets for similarity (Openness, Intellect), some for complementarity (one high and one low on Dominance often work better than two highs), and some neutrally. The ranking isn't just 'most similar'.
Can friends 'game' the test?
They can try, but the test has an embedded consistency check (repeated items phrased differently) and we surface the raw answers on your profile so a match can see your actual patterns. Gaming the test hurts your own match quality, so the incentive is mostly not there.
Give it five minutes
Meet people who actually fit — and do something real.
Free tier, Big Five test, three matches nearby. No ads, ever.