Mercor vs Scale AI: which training data company should you pick in 2026?
Answer in brief: Pick Mercor when your model has to do real professional work and you need credentialed people to write, grade and benchmark it. Mercor is our runner-up for best for LLM post-training. Pick Scale AI when you want one long-established vendor across post-training data, enterprise evaluation and fine-tuning, physical AI, automotive and the public sector. Scale is our runner-up for best for enterprise fine-tuning. This is independent research based on each company's own website and on AP and CNBC reporting. We did not test either service.
Top pick for professional-domain data: Mercor. Mercor says it has more than 5 million experts and publishes partner benchmarks with public leaderboards. If you need to know how well a model handles legal, accounting, engineering or banking work, Mercor is built for that question. Visit Mercor →
Side-by-side comparison
| Factor | Mercor | Scale AI |
|---|---|---|
| Our verdict | Runner-up: LLM post-training | Runner-up: enterprise fine-tuning |
| Founded focus | Expert hiring network turned human-data and research company | Data labeling since 2016, now data plus applications |
| Strongest data | Profession-graded evals, APEX benchmarks, RL environments | Post-training data, private leaderboards, physical AI, automotive |
| Enterprise offer | Enterprise AI with forward-deployed engineers; sale of anonymized business data | Enterprise evaluation, monitoring, RAG optimization, fine-tuning; GenAI apps |
| Notable names | Benchmark partners Harvey, Cognition, Sierra | Meta, Mayo Clinic, BP, Physical Intelligence, U.S. CDAO |
| Ownership and funding | $10B valuation, $350M round (CNBC, Oct 2025) | Meta owns 49% after a $14.3B investment (AP, June 2025) |
| Pricing | Custom | Custom, by demo |
Mercor's edge: people who have done the job
- Partner benchmarks graded on finished work. Harvey LAB scores memos and redlines. APEX-Accounting measures long-horizon tasks across accounting software, spreadsheets and PDFs. Physical-Engineering's Last Exam uses full project folders and governing codes.
- From measurement to post-training. Mercor's research team, announced October 8, 2026, builds expert data where models fail and post-trains to close the gap.
- A way to earn from your own data. Mercor's data-monetization program masks more than 60 categories of sensitive identifiers automatically and leaves you in control of what you share.
Scale AI's edge: breadth and enterprise depth
- Evaluation that feeds improvement. Scale's enterprise evaluation combines automated benchmarks, custom domain metrics, human-in-the-loop review, production monitoring and fine-tuning.
- Physical AI and defense. Scale reported more than 150,000 hours of physical-AI data, ten new robotics customers and U.S. defense contracts worth nearly $200M (January 2026).
- A profitable data business. Scale said in January 2026 that its data business was profitable while its applications revenue grew.
When to pick which
- Pick Mercor for legal, finance, accounting, medicine or engineering work, or when you want your evals tied to public leaderboards.
- Pick Scale AI for multimodal or robotics data, government programs, or an enterprise evaluation-and-fine-tuning loop run in a controlled environment.
- Check neutrality either way. If you compete with Meta, read Scale's data-isolation statement. With Mercor, confirm whether your project is run by its human-data team or its enterprise-AI team.
Pricing model
Both quote custom work. Mercor publishes what it pays experts (a $90/hr average contracted rate), which helps you estimate expert-hour costs. Scale prices by demo. See our pricing comparison.
FAQ
Is Mercor bigger than Scale AI?
By reported valuation, no. CNBC reported Mercor at $10 billion in October 2025, while Meta's 2025 investment valued Scale above $29 billion, according to Scale.
Does Scale AI do enterprise fine-tuning?
Yes. Scale's enterprise evaluation turns what it finds into improvements through RAG optimization and fine-tuning, with human-in-the-loop review.
What are Mercor's APEX benchmarks?
APEX is Mercor's benchmark family for professional work, including APEX-Accounting, APEX-SWE and APEX-Agents, with public leaderboards.
Your next move
Visit Mercor → · Visit Scale AI →
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