Prolific matters out of all proportion to its size for one reason: it is the only company in this entire vertical that publishes what it keeps.
From its own pricing page: "our platform fee is usually 42.8% for corporate customers, and a discounted 33.3% for academic or non-profit customers." Minimum participant pay is £6.00/$8.00 per hour; the recommended rate is £9.00/$12.00 (Prolific pricing).
Why 42.8% is the number to remember
The fee is charged on top of participant rewards, not deducted from them. So a researcher paying £100 to participants pays £142.80, and participants receive 100/142.80 = ~70% of total spend — which is exactly how Sacra frames the same arrangement (Sacra). The two descriptions are arithmetically identical, and that consistency is the point: this is the one place in the market where the gross and net figures can be derived from each other without a leak.
Set it against everything else that is pinned down:
| Company | Take / gross margin | Basis |
|---|---|---|
| Prolific | 42.8% fee on top of pay (~30% of gross) | Published |
| Mercor | 27% (2025), 33% (Q2 2026) gross margin | Leaked to The Information |
| Handshake AI | 60–70% paid to contractors ⇒ ~30–40% take | Reported |
| micro1 | ~30–40% implied by $150–200M net on $500M gross | Reported, internally inconsistent |
| Appen | 40.3% gross margin | Audited |
| Innodata | 49% adjusted gross margin | Audited |
Prolific's disclosure brackets Mercor's leaked margin from above, and Appen and Innodata bracket it from the public side. The convergence of six independent figures on a 30–45% band is the strongest evidence in the atlas about what this vertical's spread actually is — and it is a services spread, not a software one. See What a rake can actually be and GMV is not revenue.
What it sells now
Prolific began in 2014, founded by two Oxford PhD students, as a marketplace for academic research participants. CEO Phelim Bradley has pivoted it into AI evaluations, RLHF and red-teaming, which is where Sacra attributes the growth to ~$350M annualised as of April 2026 — a figure that, because Prolific books its platform fee rather than the participant rewards it sits on top of, is close to net and not comparable to the gross run-rates elsewhere in this vertical.
That $350M is a Sacra estimate, not a company disclosure, and is tagged [WEAK] in the research notes. Prolific has never published a revenue figure.
If the estimate is even directionally right, Prolific is the highest revenue-per-dollar-raised business in the sector: ~$350M of revenue on ~$33.4M of total capital, roughly 10x. Compare Scale AI at ~$1.6B raised, or Mercor at ~$484M.
Supply
200,000+ ID-verified active participants across 40+ countries, a 2M+ waitlist, 11,000+ AI annotation specialists and 5,000+ active AI taskers (Sacra).
Note "ID-verified." Prolific's original buyer — an academic running a behavioural experiment — cares about data integrity in a way a lab buying volume historically did not, and identity verification is baked into the product rather than bolted on. That matters more now than it did: academic work confirms that chatbot-assisted cheating contaminates crowdsourced behavioural research at scale (Asher et al., 2026). See Who is actually on the other end.
The read
Prolific sits at the cheap end of the wage ladder — $8/hr minimum, $12/hr recommended, against Handshake AI's $100–125/hr average and Mercor's $81–100+/hr. It is not competing for the same supply as the expert-data names, and it is not winning nine-figure lab contracts.
What it demonstrates is the shape of the business stripped of the GMV headline. A ~30% share of gross, a fee that is visible on the pricing page, a fragmented buyer base of researchers and labs rather than two dominant customers, and no valuation mark to defend. On One customer is a binary event alone it is structurally safer than anything else in this vertical.
Prolific's valuation, profitability, customer concentration and 2026 revenue are all undisclosed. The 42.8% fee is the only hard number the company itself has put on the record.