Index.dev vs Mercor: full comparison for 2026
Quick verdict
Index.dev (4.2/5) edges ahead of Mercor (3.7/5) overall. Index.dev is the better choice for startups that want a 30-day refundable trial before committing to a remote ML engineer. Mercor is the stronger option for AI labs and research teams that need specialist contractors in large numbers. The right choice depends on your project size, budget, and required tech stack.
Index.dev vs Mercor: head-to-head summary
| Criterion | Index.dev | Mercor |
|---|---|---|
| Founded | 2019 | 2023 |
| HQ | London, United Kingdom | San Francisco, California, USA |
| Team size | 30,000+ network | 300–400 staff; large contractor network |
| Rating | 4.2 / 5 | 3.7 / 5 |
| Primary differentiator | A 30-day trial with full refund on every placement | AI-run interviews and matching built for high-volume expert hiring |
| Pricing model | Monthly rate per engineer; direct-hire fee option; 30-day trial with refund; rates on request | Contractor rate plus platform fee (about 30%, Sacra estimate) |
| Min. engagement | Not published | Not published |
| Primary tech stack | Python, PyTorch, TensorFlow | Python, PyTorch, OpenAI |
| Industries served | SaaS, Fintech, E-commerce, Healthcare, AI labs | AI labs, Technology, Finance, Legal, Healthcare |
Index.dev vs Mercor: overview
Index.dev
Index.dev is a London company, founded in 2019 according to its own job ads, trading under the legal name Index Soft Limited. It calls itself an AI-first engineering talent platform. Its main network has more than 30,000 engineers in Latin America and Central and Eastern Europe, and a separate AI unit supplies Master's and PhD-level people for LLM fine-tuning and RAG work. Every engineer goes through five stages of vetting run by people, including a live screening call and technical validation, and Index.dev says about 1% are accepted. All placements come with a 30-day trial and a full refund if the match fails.
Mercor
Mercor was founded in San Francisco in 2023 and uses AI interviews to screen applicants. It raised money at a $10 billion valuation in October 2025, mainly on the strength of supplying experts to AI labs for model training and evaluation. Product teams can hire engineers through it, but the platform is built for volume, and Sacra estimates its fee at about 30% of contractor pay. If you want two senior ML engineers for a year-long roadmap, look elsewhere. A firm that employs and manages its people fits that job better.
Services and capabilities: Index.dev vs Mercor
| Capability | Index.dev | Mercor |
|---|---|---|
| ML engineers | ✓ | ✓ |
| LLM / GenAI engineers | ✓ | ✓ |
| AI agent developers | ✗ | ✗ |
| MLOps engineers | ✗ | ✗ |
| Computer vision engineers | ✗ | ✗ |
| NLP engineers | ✗ | ✗ |
| Data engineers | ✗ | ✗ |
| Engineer-led technical screen | ✗ | ✗ |
| Fractional / part-time experts | ✗ | ✗ |
| Trial before commitment | ✓ | ✗ |
| Nearshore time-zone overlap | ✓ | ✗ |
| Direct hire option | ✓ | ✗ |
Tech stack comparison: Index.dev vs Mercor
| Framework / platform | Index.dev | Mercor |
|---|---|---|
| PyTorch | ✓ | ✓ |
| TensorFlow | ✓ | N/A |
| LangChain | ✓ | N/A |
| Hugging Face | ✓ | N/A |
| OpenAI | ✓ | ✓ |
| AWS | ✓ | ✓ |
| Azure | N/A | N/A |
| Google Cloud | ✓ | N/A |
| Databricks | N/A | N/A |
| Kubernetes | N/A | N/A |
Pricing comparison: Index.dev vs Mercor
| Criterion | Index.dev | Mercor |
|---|---|---|
| Minimum engagement | Not published | Not published |
| Engagement models | Dedicated engineer, Dedicated team, Direct hire, Trial period | Freelance contract |
| Rate transparency | Not public | Not public |
| Price tier | Mid-market | Mid-market |
Target audience comparison: Index.dev vs Mercor
| Dimension | Index.dev | Mercor |
|---|---|---|
| Best company size | Startup to mid-market | Startup to mid-market |
| Best industries | SaaS, Fintech, E-commerce | AI labs, Technology, Finance |
| Best use cases | Trialling a Latin American ML engineer for a month before committing, Hiring a PhD-level specialist to fine-tune an open-source LLM | Hiring dozens of domain experts to evaluate a model, Adding a contract ML engineer for a research sprint |
| Typical project type | Dedicated engineer | Freelance contract |
Index.dev vs Mercor: pros and cons
| Index.dev | |
|---|---|
| + | The 30-day refundable trial is the most generous published trial on this page |
| + | A separate AI unit for advanced work such as fine-tuning |
| + | Clients can hire directly as well as contract |
| - | Vetting is human-led but not specifically run by ML engineers |
| - | Network figures and acceptance rates are company claims |
| - | Founding date only appears in job listings |
| Mercor | |
|---|---|
| + | Fast access to a large pool of specialists |
| + | Well funded |
| + | Experienced with AI-lab evaluation and training work |
| - | AI interviews, not engineers, do the first screen |
| - | Fee of about 30% adds up over a long engagement |
| - | Founded in 2023, so a short track record with product teams |
Who should choose Index.dev?
A typical fit: trialling a Latin American ML engineer for a month before committing.
A 30-day trial with full refund on every placement. Minimum engagement is not publicly disclosed. Works best with clients in SaaS, Fintech, E-commerce, Healthcare, AI labs.
Who should choose Mercor?
A typical fit: hiring dozens of domain experts to evaluate a model.
AI-run interviews and matching built for high-volume expert hiring. Minimum engagement is not publicly disclosed. Works best with clients in AI labs, Technology, Finance, Legal, Healthcare.
Decision matrix: Index.dev vs Mercor
| Your situation | Recommended choice |
|---|---|
| You want a working engineer, not a recruiter, to run the technical screen | Neither documents an engineer-led screen; run your own technical interview |
| You need one specialist for a few days a week | Neither advertises part-time experts; ask about reduced hours |
| You need several engineers working as one team | Neither lists dedicated teams; check team size before signing |
| You want to test an engineer before committing | Index.dev |
| Your budget is at the lower end | Compare: Index.dev (Not published) vs Mercor (Not published) |
| Your team works U.S. hours | Index.dev |
| You may want to hire the engineer permanently later | Index.dev |
Use case fit: Index.dev vs Mercor
| Use case | Index.dev fit | Mercor fit | Winner |
|---|---|---|---|
| Trialling a Latin American ML engineer for a month before committing | Strong | Limited | Index.dev |
| Hiring a PhD-level specialist to fine-tune an open-source LLM | Strong | Strong | Both equally |
| Hiring dozens of domain experts to evaluate a model | Strong | Strong | Both equally |
| Adding a contract ML engineer for a research sprint | Limited | Strong | Mercor |
Verdict: Index.dev vs Mercor
Index.dev (4.2/5) is the stronger overall choice for most AI Engineer Staffing projects. A 30-day trial with full refund on every placement.
Mercor (3.7/5) is worth a look if you need adding a contract ML engineer for a research sprint. If your situation matches that, Mercor is a competitive option.
Related comparisons
Index.dev vs Mercor FAQ
Is Index.dev better than Mercor?
Index.dev (4.2/5) scores higher overall, but "better" depends on your use case. Index.dev's strongest advantage: the 30-day refundable trial is the most generous published trial on this page. Mercor's strongest advantage: fast access to a large pool of specialists.
How do Index.dev and Mercor differ in pricing?
Index.dev uses monthly rate per engineer; direct-hire fee option; 30-day trial with refund; rates on request pricing. Mercor uses contractor rate plus platform fee (about 30%, sacra estimate) pricing. Neither firm publishes a full rate card; a discovery call is required for project-specific quotes.
Which is better for enterprise: Index.dev or Mercor?
Mercor is the larger team and typically the better enterprise-scale choice. For very large programmes, verify team size and compliance coverage directly with each company before shortlisting.
What are the main differences between Index.dev and Mercor?
Index.dev's primary differentiator is: a 30-day trial with full refund on every placement. Mercor's primary differentiator is: AI-run interviews and matching built for high-volume expert hiring. They also differ in team size (30,000+ network vs 300–400 staff; large contractor network), minimum engagement (Not published vs Not published), and primary industries served (SaaS, Fintech vs AI labs, Technology).
Verify all details directly with each company before making a decision.