TL;DR: Koji and Prolific get compared a lot, but they solve different halves of the research problem. Prolific is a participant recruitment panel — it gives you access to 200,000+ vetted, fairly paid respondents, then you take them to a survey or interview tool of your own. Koji is the end-to-end, AI-native research platform that designs the study, runs AI-moderated voice and text interviews, probes for the "why," and delivers analyzed insights in hours. If you only need bodies for a questionnaire you already built, Prolific is a marketplace. If you need the research itself — moderation, follow-up probing, thematic analysis, and a finished report — Koji does the work, and pairs cleanly with any panel (Prolific included) when you need fresh respondents.
Quick comparison: Koji vs Prolific at a glance
| Koji | Prolific | |
|---|---|---|
| What it is | End-to-end AI customer research platform | Participant recruitment panel |
| Runs the interview/survey | Yes — AI-moderated voice + text | No — you run it in another tool |
| AI moderation & follow-up probing | Yes | No |
| Automatic thematic analysis | Yes | No |
| One-click insight reports | Yes | No |
| Structured question types | 6 (open-ended, scale, single choice, multiple choice, ranking, yes/no) | N/A — depends on your tool |
| Participant sourcing | Built-in panel recruitment (credit-quoted) + bring-your-own | 200,000+ active vetted participants (1M+ total pool) |
| Pricing | From €1 per qualified interview; pay as you go, no subscription | Platform fee on top of participant pay (33.3% academic / 42.8% commercial) |
| Best for | Teams who need insights, not just respondents | Researchers who already have a study and just need participants |
What is Prolific?
Prolific is an online participant recruitment platform with a pool of 200,000+ active, ID-verified participants and more than a million people total. It built its reputation in academia, where its fair-pay standards stand out: Prolific enforces a minimum participant rate of $8.00/£6.00 per hour and recommends at least $12.00/£9.00 per hour. Pricing for researchers is pay-as-you-go — you pay each participant for their time, plus a platform fee on top (around 33.3% for academic and non-profit users and 42.8% for commercial customers).
The key thing to understand: Prolific is not a research tool. It does not host your questionnaire, moderate a conversation, ask intelligent follow-up questions, or analyze what people say. You design your study somewhere else — Qualtrics, Google Forms, a usability tool — and route Prolific participants into it. Prolific answers one question extremely well: who will I talk to?
What is Koji?
Koji is an AI-native customer research platform that runs the entire research workflow for you. From a short brief, Koji's customizable AI consultant designs the study, then conducts AI-moderated voice interviews (powered by ElevenLabs) and text interviews that adapt in real time, probing each respondent for the reasoning behind their answers — with no moderator bias and 24/7 availability. Every transcript is automatically themed with supporting quotes, and you get a shareable insight report in one click.
Koji also lets you mix six structured question types in a single study — open-ended, scale, single choice, multiple choice, ranking, and yes/no — so one conversation produces both qualitative depth and quantitative structure. Pricing is transparent and accessible. Interviews start as low as €1 per qualified interview, and €3 per qualified voice interview. You get 10 free credits at signup, no card, then pay as you go with no subscription needed. There is no overage. You pay as you go, and you only ever pay for the conversations that bring insights.
Koji answers the question Prolific doesn't: how do I actually get the insight?
The core difference: recruitment vs research
This is the whole comparison in one line. Prolific is supply: a fast, ethical, well-vetted pool of humans. Koji does both halves. Panel recruitment is built in, so you describe the audience you want and approve a live per-respondent quote in credits before launch, and then Koji does the research: the moderation, the probing, the analysis, and the report. Buying a Prolific seat and expecting finished insights is like hiring a catering staffing agency and expecting a menu: you'll get great people, but someone still has to cook.
In practice, teams that try to do depth research with a panel alone end up stitching together three or four tools: the panel for recruitment, a survey builder for the questionnaire, a transcription tool, and a spreadsheet (or an analyst) for coding. Koji collapses that stack. Learn more in our guide to the automated user research platform and how AI-moderated interviews replace manual moderation.
Where Prolific wins
- Large representative quantitative samples. If you need 1,000 demographically balanced responses for a statistical study, Prolific's pool and screening are purpose-built for it.
- Academic and AI-data work. Strict pay ethics and ID verification make it a default for universities and for sourcing high-quality human data for model training and evaluation.
- Speed of sourcing. A pre-vetted, responsive pool fills studies fast when you bring your own instrument.
Where Koji wins
- Depth, not just data. AI follow-up probing surfaces the why behind every answer — the part a static survey can never capture. Industry data backs this up: AI-moderated interviews have been shown to generate roughly 4.5x more insightful responses than traditional surveys.
- No moderator bias, infinite scale. Every participant gets the same consistent, adaptive interview, day or night. See AI vs human moderators.
- Analysis is included. No manual transcript coding — themes, sentiment, and quotes are generated automatically. Compare approaches in AI interviews vs surveys.
- Mixed-method in one study. Six structured question types mean you don't choose between qualitative and quantitative — you get both.
- Transparent pricing. No per-response platform fees stacking up; interviews as low as €1 per qualified interview and €3 per qualified voice interview.
Can you use Koji and Prolific together?
Yes: and it's a great combination. Koji has panel recruitment built in (describe your audience, approve a per-respondent quote in credits), and it also works with respondents you bring yourself, so you can source fresh, screened respondents from a panel like Prolific and then run the actual AI-moderated interview and analysis in Koji. You get Prolific's reach plus Koji's depth and automated insight — without the manual coding in between.
Pricing compared
Prolific's cost scales with sample size and the fee on top of participant pay, which is appropriate for one-off quantitative fielding but unpredictable for ongoing discovery. Koji's pricing, as low as €1 per qualified interview and €3 per qualified voice interview, is built for continuous research — weekly discovery, churn interviews, concept tests — where you're running studies all the time rather than fielding a single large survey.
Which should you choose?
- Choose Prolific if you already have a survey or experiment built, need a large representative sample, and your priority is ethically-paid, verified participants at scale.
- Choose Koji if you need the research done — adaptive interviews, the reasoning behind the numbers, and analyzed insights without hiring a moderator or an analyst.
- Choose both if you want panel reach and AI-moderated depth in one workflow.
The bottom line
Prolific is a strong answer to "where do I find participants?", and Koji answers that one too: describe the audience and approve a per-respondent quote in credits. Koji is the best answer to "how do I turn conversations into decisions — fast?" For most founders, PMs, and lean research teams in 2026, the bottleneck isn't finding people; it's turning what they say into insight without weeks of manual work. That's the gap Koji closes.
Ready to go from question to insight in hours, not weeks? Start free with Koji — get 10 credits to run your first AI-moderated study today. Bring your own respondents, let Koji recruit them for you, or use a panel like Prolific when you prefer.
