How do their growth rates compare?

Prolific has a month-over-month growth rate of -1.8%; Reos has -84.8%.

How does pricing compare?

Prolific: Paid. Usage-based for requesters: you pay participant rewards plus a platform fee, with custom quotes for large or managed programmes. Participants earn per completed study; joining is free. Reos: Paid, Contact for Pricing. Enterprise-oriented: Reos lists a Pricing section and an Enterprise plan, and guides visitors to sign up or book a demo. Specific tiers and prices are not published on the public homepage, so contact the team for a quote.

What are alternatives to Prolific and Reos?

Other tools in related categories include Branded, Listen Labs, Labelbox, Appen, Outset.ai.

Prolific vs Reos — Traffic (18.7M vs 533), Pricing & Verdict

Open AI Tools

Prolific vs Reos — Traffic (18.7M vs 533), Pricing & Verdict | Open AI Tools

Side-by-Side Traffic & Specification Matrix

Dimension / Metric	Prolific	Reos
Official Domain	prolific.com	reos.ai
Pricing Model	Paid	Paid, Contact for Pricing
Monthly Visits	18.7M (18,697,671)	533 (533)
MoM Traffic Delta	-352.04K (-1.8%)	-2.97K (-84.8%)
Primary Market & Share	🇺🇸 United States (48.8%)	🇺🇸 United States (100%)
Direct Visits / mo	12.98M	209
User Rating	4.6	4.2
Supported Platforms	Website	Website

Prolific

High-quality human data for AI training, evaluation, and research

Verified, targetable participant pool

Filter participants by detailed demographic, professional, and behavioural criteria and reach narrow or representative samples rather than a generic crowd.

AI data and human feedback

Collect human preference data for model fine-tuning, run safety evaluations and red-teaming, and use a feedback API to plug humans into automated pipelines.

Built-in data-quality controls

Attention checks, honesty screening, and approval workflows help filter out careless or fraudulent responses before you analyse results.

Fast study launches

Publish a study and begin collecting responses quickly, with tooling that supports screening, quotas, and longitudinal designs.