High-quality human data for AI training, evaluation, and research
SourceBae: Connects AI enterprises with specialized domain experts for data collection and evaluation, but has a smaller talent pool. OpenTrain AI records 1,469,348 monthly visits with +11.2% month-over-month growth and Contact for Pricing pricing. SourceBae records 21,727 monthly visits with +20.1% growth and Contact for Pricing pricing.
Train AI with domain experts and real-world data
| Dimension / Metric | ![]() | |
|---|---|---|
| Official Domain | opentrain.ai | sourcebae.com |
| Pricing Model | Contact for Pricing | Contact for Pricing |
| Monthly Visits | 1.47M (1,469,348) | 21.73K (21,727) |
| MoM Traffic Delta | +147.68K (+11.2%) | +3.63K (+20.1%) |
| Primary Market & Share | 🇺🇸 United States (18.6%) | 🇮🇳 India (80.7%) |
| Direct Visits / mo | 607.07K | 3.66K |
| User Rating | 4.2 | 4.1 |
| Supported Platforms | Website | Website |

Hire tested AI trainers and data labelers for RLHF, evaluation, and annotation
Post a project and receive a shortlist drawn from a network of more than 711,000 people across 240+ countries, available in 120+ languages.
Applicants pass automated interviews and domain skill assessments, and managed programs add live proctored testing, so candidates are matched on demonstrated ability rather than self-reported skills.
Hire managers can add experts straight into Label Studio, CVAT, Labelbox, Argilla, or another tool they already run, avoiding data migration.
Beyond standard labeling, the network covers RLHF preference ranking, DPO pair generation, reasoning verification, adversarial red teaming, and human benchmarking.
Train AI with domain experts and real-world data
Generate supervised fine-tuning prompts, reference answers, demonstrations and review rubrics with specialists matched to your subject area rather than generalist annotators.
Collect comparison data on accuracy, relevance, instruction following and domain quality so models can be tuned against ranked human preferences.
Capabilities Assessment responses against expert-defined criteria to surface errors, knowledge gaps and inconsistent behaviour, and run adversarial prompts to expose safety failures.
Capture real tasks in households, factories, warehouses, workshops, farms, labs and clinical settings to build training data for robotics and Physical AI.
High-quality human data for AI training, evaluation, and research

AI-powered talent marketplace connecting experts with frontier AI work

Free / Open-sourceThe agent recruits, you manage talent

Massive global pool of subject matter experts for RLHF and model training, but features less personalized curation.
Massive global pool of subject matter experts for RLHF and model training, but features less personalized curation.

SpecialistOffers crowdsourced data collection and annotation at scale, but lacks specialized frontier-model RLHF training workflows.
SpecialistOffers crowdsourced data collection and annotation at scale, but lacks specialized frontier-model RLHF training workflows.
Agentic skills intelligence for hiring, developing, and planning talent

SpecialistEnterprise-grade data labeling and annotation platform, but places more emphasis on tooling than direct expert recruitment.
SpecialistEnterprise-grade data labeling and annotation platform, but places more emphasis on tooling than direct expert recruitment.

AI-powered candidate matching inside Arc's vetted remote-talent marketplace
AI-powered candidate matching inside Arc's vetted remote-talent marketplace

SpecialistAdvanced multimodal data annotation platform with robust enterprise management tools, but relies more on software than managed talent.
SpecialistAdvanced multimodal data annotation platform with robust enterprise management tools, but relies more on software than managed talent.

Hire real people for tasks AI agents can't do in the physical world
Hire real people for tasks AI agents can't do in the physical world

Provides highly vetted human data and evaluation workforces for frontier labs, but caters primarily to enterprise clients.
Provides highly vetted human data and evaluation workforces for frontier labs, but caters primarily to enterprise clients.
Free / Open-sourceFree open course for prompt engineering and AI security
Free / Open-sourceFree open course for prompt engineering and AI security