OpenTrain AI records 1,469,348 monthly visits with +11.2% month-over-month growth and Contact for Pricing pricing. StackRef records 765 monthly visits with +184.4% growth and Contact for Pricing pricing.
Hire tested AI trainers and data labelers for RLHF, evaluation, and annotation
Senior cloud, DevOps and security consulting plus a self-hosted hackathon manager
| Dimension / Metric | | |
|---|---|---|
| Official Domain | opentrain.ai | stackref.com |
| Pricing Model | Contact for Pricing | Contact for Pricing |
| Monthly Visits | 1.47M (1,469,348) | 765 (765) |
| MoM Traffic Delta | +147.68K (+11.2%) | +496 (+184.4%) |
| Primary Market & Share | 🇺🇸 United States (18.6%) | 🇮🇩 Indonesia (100%) |
| Direct Visits / mo | 607.07K | 305 |
| User Rating | 4.2 | 4 |
| 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.
Senior cloud, DevOps and security consulting plus a self-hosted hackathon manager
Hands-on architecture, security, and cost optimization across AWS, GCP, and Azure, led by a CISSP-certified architect with 20+ years of experience.
Focused engagements on hardening cloud environments and supporting compliance, with an emphasis on robust, well-governed infrastructure.
Practical work to reduce cloud spend and right-size infrastructure without sacrificing reliability.
A self-designed, self-hosted, end-to-end internal hackathon manager covering sandbox environments and AI scoring to run innovation events.
AI-driven talent marketplace matching domain experts with AI labs, focusing more on long-term remote roles than short tasks.
AI-driven talent marketplace matching domain experts with AI labs, focusing more on long-term remote roles than short tasks.
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.
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.
Free / Open-sourceGoogle's batteries-included framework for scalable web apps
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.
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
Free / Open-sourceCommunity hub for data science, machine learning and AI practitioners
Free / Open-sourceCommunity hub for data science, machine learning and AI practitioners
SpecialistThe job board built for AI, ML, and data science careers
SpecialistLow-smoke, halogen-free rigid PVC conduit for safer electrical containment
SpecialistLow-smoke, halogen-free rigid PVC conduit for safer electrical containment
Connects AI enterprises with specialized domain experts for data collection and evaluation, but has a smaller talent pool.
Connects AI enterprises with specialized domain experts for data collection and evaluation, but has a smaller talent pool.
