IPIP — International Personality Item Pool
The single best hub for free, public-domain measurement: 3,000+ items and 250+ scales covering almost any personality construct. Explicitly public domain — use, edit, or embed without asking.
Annotated resource collections
The Library
Annotated collections of tools for understanding yourself — personality, values, moral psychology, mental health. The internet has no shortage of quizzes; what's scarce is a map of which instruments the evidence actually supports. Everything listed here has a real research base, every annotation says plainly what a tool measures and where its weaknesses are, and the popular tests that don't hold up aren't here — except in the section explaining why.
Personality & Individual Traits
Big Five, HEXACO, dark traits, empathy, and the single-construct classics — the trait models that actually replicate.
12 tools annotatedValues & Moral Psychology
What you prioritize, what your moral intuitions are built from, how you reason about dilemmas, and how central morality is to your identity.
10 tools annotatedMental Health & Wellbeing
The screening instruments clinics and researchers actually use — mood, anxiety, sleep, stress, and beyond — plus a short section on cognitive performance testing.
27 tools annotatedHow to read these lists
Every entry carries an evidence tier and access badges, so you can tell at a glance whether a tool is science or folklore, and whether using it costs anything.
- Strong evidence
- Replicated factor structure, cross-cultural validation, active mainstream use in peer-reviewed research.
- Moderate evidence
- A real evidence base, but with active psychometric debate, known limitations, or replication still accumulating. The annotation names the specific concern.
- Free · scored onlineFree · items + scoring keyProprietary · paid
- Access badges distinguish tools you can take scored in the browser, free item sets you score yourself, and instruments that cost money or can only be scored through a gatekeeping organization.
Meta-resources & hubs
Where to look when you want something these collections don't cover yet.
PsyToolkit Survey Library
A large library of ready-to-run academic questionnaires with citations for each — free for students and academics, and a useful reference for everyone else.
Open-Source Psychometrics Project
A huge, deliberately mixed-quality collection of interactive tests — serious instruments and self-produced quizzes side by side. Read the notes on each specific test before trusting it; as a discovery tool and open-data project, it's excellent.
YourMorals.org
The Haidt/Graham research group's public-facing site: take the Moral Foundations Questionnaire and related instruments and see how you compare with the aggregate dataset.
HealthMeasures (PROMIS)
The NIH-funded home of PROMIS — patient-reported outcome measures for emotional distress, sleep, fatigue, pain, and social function, built with modern psychometrics (item response theory) and free to use.
What you won't find here
Curation means saying no. These are excluded on the evidence — not because they're obscure, but despite being everywhere.
MBTI. Splits continuous traits into 16 boxes, and test-retest agreement is poor — a large share of people get a different type within weeks. Everything real it captures, the Big Five captures with better psychometrics.
Enneagram. A rich reflective tradition with thin empirical validation — type assignment is unreliable and the nine-type structure hasn't survived psychometric scrutiny.
DISC. Ubiquitous in workplace trainings; the peer-reviewed validity evidence outside vendor materials is remarkably thin for something so widely sold.
Learning styles (VARK and kin). The core claim — that matching instruction to your 'style' improves learning — has repeatedly failed controlled tests.
A useful rule for anything not listed: if a test only ever tells you flattering things, it's marketing. Real instruments have score distributions, known error, and at least one finding their authors wish weren't true.