TL;DR: Choose User Interviews if you need a large consumer and UX panel (~7.5M participants across 34 countries) plus tooling to run moderated and unmoderated product studies and manage your own recruited pool. Choose Prolific if you're running surveys and academic-grade studies that demand tight data quality, representative sampling, and transparent per-participant cost — its ~300K vetted pool, attention checks, and reproducibility controls are why researchers trust it. But both platforms only recruit participants. Once someone is booked, you still schedule, moderate, transcribe, and analyze every session yourself. Koji handles that second half: its AI moderates adaptive voice or text interviews and themes the results into a report automatically. Koji starts free, then €29/month.
User Interviews vs Prolific at a glance
| User Interviews | Prolific | |
|---|---|---|
| Panel size | ~7.5M participants, 34 countries | ~300K active participants (1M+ waitlist) |
| Audience strength | Consumers, UX/product participants, some B2B | Vetted research participants, representative samples |
| Best for | Moderated + unmoderated product research | Surveys, experiments, academic-grade studies |
| Pricing model | PAYG from ~$49/session + subscriptions | PAYG; platform fee added on top of incentives |
| Data-quality controls | Screeners, participant ratings | Attention checks, ID verification, reproducibility |
| Runs the interview for you? | No — recruiting only | No — recruiting only |
| Analyzes the data for you? | No | No |
Both are excellent at what they do: finding the right people. Neither runs or analyzes the research. That distinction is the whole story — so keep it in mind as we go.
The problem both tools solve (and the one they don't)
Recruiting is genuinely hard. In one widely cited industry survey, 61% of researchers said finding participants was their biggest time sink in 2024, up from 45% the year before. That is exactly the pain User Interviews and Prolific exist to remove.
But recruiting is only the first half of a research project. After a participant is booked, someone still has to schedule the session, moderate it live, take notes, transcribe the recording, tag the themes, and write the report. That back half is where most research hours disappear — and neither User Interviews nor Prolific touches it. See how to recruit user research participants for the full recruiting playbook, and /docs/finding-research-participants for Koji's approach.
User Interviews: the consumer and UX recruiting workhorse
User Interviews runs one of the largest research panels available — roughly 7.5 million participants across 34 countries — and in January 2026 it was acquired by UserTesting, folding it into a broader customer-insights suite. It shines when you need consumers or everyday product users fast, and it offers a Hub for managing participants you've recruited yourself.
Pricing. The Recruit pay-as-you-go plan starts around $49 per session, with subscription tiers (Essential and Professional) lowering the per-session rate for committed volume. Incentives paid to participants are separate, so a fully loaded completed interview commonly lands in the $130–$282 range once you add the incentive. If you're weighing it against the field, our User Interviews alternatives guide breaks down the post-acquisition options.
Strengths: huge consumer reach, fast fielding, strong screener and scheduling automation, own-panel management. Limits: per-session cost adds up, incentives are extra, and — critically — it stops at the handoff. You still run and analyze every conversation.
Prolific: the data-quality and academic favorite
Prolific is built for surveys and experimental studies where data quality is everything. Its pool of 300,000+ active participants (with over a million on the waitlist) is vetted, ID-verified, and subject to attention checks and reproducibility standards that academic and quant teams depend on. It's the go-to when you need a representative sample or clean survey data at scale.
Pricing. Prolific is pure pay-as-you-go with no monthly fees. You pay participants directly — Prolific recommends at least £9/$12 per hour (minimum £6/$8) — and the platform adds a fee on top: 42.8% for corporate customers, 33.3% for academic and non-profit users. So a study with $70 in participant payments costs roughly $100 all-in for a corporate account. Pricing is refreshingly transparent, but the model is optimized for short, structured tasks, not deep two-way conversations.
Strengths: best-in-class data quality, representative sampling, transparent cost, ideal for surveys and experiments. Limits: smaller pool than consumer panels, less suited to long qualitative interviews, and — like User Interviews — it recruits but never moderates or analyzes. Compare the depth trade-off in surveys vs interviews: when to use each.
User Interviews vs Prolific: which should you pick?
- Pick User Interviews if your work is product/UX research, you need consumers fast, you want scheduling automation, or you're managing your own panel.
- Pick Prolific if you're running surveys or experiments, need representative samples, care most about data quality and reproducibility, or you're on an academic/non-profit budget.
- Pick neither alone if your real goal is insight, not just a booked calendar slot — because that's where both stop.
Recruiting is half the job. Koji does the other half.
Here's what neither platform does: run the interview and analyze it for you. Koji is an AI-native research platform that moderates the conversation and themes the results automatically.
- AI-moderated voice or text interviews. Koji's AI asks your questions, listens, and — unlike a static survey — asks adaptive follow-ups in the moment, with no scheduling and no no-shows. Learn how at /docs/ai-moderated-interviews.
- Six structured question types. Every study can mix qualitative and quantitative signal in one flow:
open_ended,scale,single_choice,multiple_choice,ranking, andyes_no. Details at /docs/structured-questions-guide. - Automatic thematic analysis. When interviews finish, Koji themes every conversation and produces a one-click report with quotes and sentiment — see /docs/thematic-analysis-guide and /docs/generating-research-reports. No moderator bias, no manual coding.
- Fewer participants, deeper data. Because each AI interview probes deeper than a survey and analysis is instant, you typically need fewer recruited participants — which lowers your User Interviews or Prolific bill.
The winning workflow is not either/or. Recruit hard-to-reach or representative participants on User Interviews or Prolific, then send them a Koji link. Koji interviews them on their own schedule and hands you the analysis — turning a two-week research slog into hours. See how Koji compares directly to Prolific and to User Interviews.
The bottom line
User Interviews and Prolific are both great — at recruiting. User Interviews wins on consumer reach and product-research tooling; Prolific wins on data quality and representative sampling for surveys. But recruiting is only half the job, and the expensive half — moderating and analyzing — is still on you.
Koji closes that gap. Pair a panel for reach with Koji for the actual interviewing and analysis, or run end-to-end on Koji when you can bring your own audience. Start free, then €29/month — question to insight in hours, not weeks.
Ready to stop analyzing interviews by hand? Try Koji free and run your first AI-moderated study today.
