# Appen vs mcp.so

Appen records 665,840 monthly visits with +0.2% month-over-month growth and Contact for Pricing pricing. mcp.so records 286,704 monthly visits with -3% growth and Free pricing.

| Metric | [Appen](https://openaitools.app/tool/appen-com) | [mcp.so](https://openaitools.app/tool/mcp-server) |
| :--- | :--- | :--- |
| Website URL | https://appen.com | https://mcp.so |
| Categories | AI Models, Large Language Models (LLMs), AI Developer Tools | AI Tools Directory, Large Language Models (LLMs), AI Developer Tools |
| Pricing Model | Contact for Pricing | Free |
| Monthly Visits | 665,840 | 286,704 |
| MoM Growth Rate | +0.2% | -3% |
| Primary Market | United States | United States |
| Direct Visits | 238,314 | 107,648 |
| Review Score | 4.4 | 4.2 |
| Saved Count | 2 | 0 |
| Supported Platforms | Website | Website |

## Appen

Appen is one of the oldest pure-play AI data companies, tracing its roots to 1996 when it began building human-labeled datasets for speech recognition and NLP. Over three decades it supported successive generations of model development — search relevance in the 2000s, machine translation, deep-learning vision annotation, Transformer-era semantics, GPT-3 scale corpora, RLHF for conversational AI, and now agentic and multimodal foundation models.

Today Appen positions itself around six specialised capability areas: Frontier Alignment (chain-of-thought reasoning traces, SME RLHF, supervised fine-tuning demonstrations, adversarial red teaming), Agentic AI (golden trajectories, RL environment design, failure-mode taxonomies, SWE-driven evaluation), Multimodal and Speech AI (multilingual ASR and conversational corpora, expressive TTS annotation, VLM training data, video action labelling), Physical AI (LiDAR point-cloud annotation, multi-camera sensor fusion, robotics demonstration trajectories, world-model rollouts), Model Integrity (hallucination benchmarking, bias detection, regulatory audits and continuous monitoring), and Research Services (context engineering, calibrated LLM-as-a-judge, synthetic data and custom benchmarking).

Delivery runs through Appen's AI Data Platform (ADAP), which blends automation with human oversight, and the company cites SOC 2 and ISO 27001 certification, 500+ global locales, and a client roster that includes major cloud, search, retail and aerospace organisations. Appen does not publish self-serve pricing; engagements start with a scoping conversation and are quoted per project, so cost depends on data volume, language coverage, modality and annotation complexity.

**Pricing & Plans:** Enterprise/contact-for-pricing. Appen does not publish self-serve plans; projects are scoped and quoted individually. Appen also sells off-the-shelf (OTS) datasets and crowd/contractor workforce programs with separate terms.

- **Frontier alignment data:** Chain-of-thought reasoning traces, SME-level RLHF, supervised fine-tuning demonstrations and adversarial red teaming for the most capable models.
- **Agentic AI datasets:** Golden trajectories, RL environment design, failure-mode taxonomies and software-engineering-driven deep evaluation for autonomous agents.
- **Multimodal and speech corpora:** Multilingual ASR and conversational speech data, expressive TTS annotation, vision-language model training data, video action labelling and voice-agent evaluation.
- **Physical AI annotation:** LiDAR point-cloud labeling, multi-camera sensor fusion, robot demonstration trajectories, world-model rollouts and embodied interaction logs.
- **Model integrity and evaluation:** Hallucination benchmarking, bias detection, regulatory audits and continuous monitoring, plus independent model evaluation.
- **AI Data Platform (ADAP):** A production platform that combines automation with human oversight, with SOC 2 and ISO 27001 certification and 500+ locales covered.

**Strengths:** Three decades of annotation methodology, tooling and workforce management experience; Very broad coverage: frontier alignment, agentic, speech, multimodal, physical AI and evaluation in one vendor; 500+ locales and multilingual expertise that most in-house teams cannot match; Enterprise-grade security posture (SOC 2, ISO 27001) and publicly listed governance

**Limitations:** No transparent self-serve pricing; every engagement requires a sales/scoping cycle; Enterprise-oriented contracts can be heavy for small teams or indie developers; Quality depends on workforce management, so results vary by project and locale; Overlaps with many cheaper specialist annotation vendors, making vendor selection non-trivial

[Profile (Markdown)](https://openaitools.app/tool/appen-com.md)

## mcp.so

mcp.so organises the fast-growing Model Context Protocol ecosystem in one searchable place. You can browse servers by category (developer tools, AI and agents, cloud infrastructure, memory and knowledge, media and design), inspect remote endpoints, and read setup details before wiring a server into Claude, Cursor or another MCP-compatible client. Featured and trending sections surface popular or newly added servers, and rankings help you gauge what the community is adopting.

Beyond raw server listings, the site collects MCP clients (apps, IDEs and frameworks that speak the protocol), official CLI tools such as Bun, Cloudflare Wrangler, DuckDB and FFmpeg, reusable agent loops and skills, and curated collections. A feed tracks new arrivals, and submit/claim flows let maintainers add or take ownership of their own listings.

For anyone building with AI agents, mcp.so works as a discovery and reference layer: pick a capability, check how the server connects and authenticates, follow the setup guide, and keep an eye on what the community is installing each week. It is a directory, so it does not itself host or run the servers it lists.

**Pricing & Plans:** Free to browse and use the directory. Advertising, featured placement and claiming listings are handled through the site; no subscription is required for normal browsing.

- **Searchable MCP server directory:** Find servers by name, category, tag, runtime or integration, with featured, trending and newest sections that track community activity.
- **Remote endpoints and setup guides:** Review hosted MCP endpoints, authentication requirements and per-client setup instructions before you connect anything.
- **Clients, CLI tools and skills:** Discover MCP-compatible clients, official command-line tools, agent loops and reusable Claude/Codex skills in dedicated sections.
- **Submit and claim listings:** Maintainers can publish new servers and claim existing listings so entries stay accurate and attributable.
- **Categories, rankings and feed:** Browse top categories, compare curated selections and follow a live feed of newly added servers, tools and skills.

**Strengths:** Broad, regularly updated coverage of MCP servers and clients; Setup and authentication details gathered together in one place; Free to use with no account needed for browsing; Includes CLI tools, agent skills and curated collections beyond raw listings

**Limitations:** Listings are community-submitted, so quality and freshness can vary; It is a directory only, not a place to run or host MCP servers; Ad and featured placements can push less relevant results higher

[Profile (Markdown)](https://openaitools.app/tool/mcp-server.md)

## Frequently Asked Questions

### How do Appen and mcp.so compare in monthly traffic?

Appen has 665,840 monthly visits, while mcp.so has 286,704. Traffic estimates describe audience size, not product quality.

### How do their growth rates compare?

Appen has a month-over-month growth rate of +0.2%; mcp.so has -3%.

### How does pricing compare?

Appen: Contact for Pricing. Enterprise/contact-for-pricing. Appen does not publish self-serve plans; projects are scoped and quoted individually. Appen also sells off-the-shelf (OTS) datasets and crowd/contractor workforce programs with separate terms. mcp.so: Free. Free to browse and use the directory. Advertising, featured placement and claiming listings are handled through the site; no subscription is required for normal browsing.

## Alternatives

| # | Tool Name | Monthly Visits | MoM Growth Rate | Pricing Model | Summary | Profile (Markdown) |
| :--- | :--- | :--- | :--- | :--- | :--- | :--- |
| 1 | [Prolific](https://openaitools.app/tool/prolific-com) | 18,697,671 | -1.8% | Paid | Connects teams directly with verified human participants for preference tuning and studies, but lacks managed end-to-end labeling pipelines. | [.md](https://openaitools.app/tool/prolific-com.md) |
| 2 | [Invisible Technologies](https://openaitools.app/tool/invisible-technologies-inc) | 1,364,520 | +64.4% | Contact for Pricing | Blends custom software with dedicated human expert teams to handle complex operations, but operates as a bespoke service. | [.md](https://openaitools.app/tool/invisible-technologies-inc.md) |
| 3 | [Labelbox](https://openaitools.app/tool/labelbox) | 762,803 | -22.8% | Contact for Pricing | Combines robust data labeling tools with automated workflows, but focuses more on software tooling than managed human workforces. | [.md](https://openaitools.app/tool/labelbox.md) |
| 4 | [Scale](https://openaitools.app/tool/scale) | 616,915 | +12.5% | Contact for Pricing | Provides enterprise-grade AI training data and model evaluation at massive scale, but often with higher enterprise pricing. | [.md](https://openaitools.app/tool/scale.md) |
| 5 | [Dang.ai](https://openaitools.app/tool/dang-ai) | 552,907 | +17.5% | Free | Curated directory and search engine cataloging thousands of general AI products rather than MCP developer integrations. | [.md](https://openaitools.app/tool/dang-ai.md) |
| 6 | [Futurepedia](https://openaitools.app/tool/futurepedia-find-the-best-ai-tools-software) | 527,719 | +22.5% | Free | Massive general AI tools directory, offering broader software discovery but less focus on specific MCP servers. | [.md](https://openaitools.app/tool/futurepedia-find-the-best-ai-tools-software.md) |
| 7 | [SkillsMP — Agent Skills Marketplace](https://openaitools.app/tool/agent-skills-marketplace) | 470,744 | -3.7% | Free | Independent public directory indexing open-source agent skill files and MCP integrations for AI developers. | [.md](https://openaitools.app/tool/agent-skills-marketplace.md) |
| 8 | [SuperAnnotate](https://openaitools.app/tool/super-annotate) | 386,034 | +37.4% | Free Trial, Contact for Pricing | Delivers advanced multimodal data curation and annotation infrastructure, but requires your own annotation workforce for labeling tasks. | [.md](https://openaitools.app/tool/super-annotate.md) |
| 9 | [Arize AI](https://openaitools.app/tool/arize-com) | 249,028 | +3.2% | Paid, Contact for Pricing | Agent observability, evaluation, and continuous improvement for production AI | [.md](https://openaitools.app/tool/arize-com.md) |
| 10 | [Encord](https://openaitools.app/tool/encord-com) | 244,204 | +9.4% | Contact for Pricing | The multimodal data layer for computer vision and physical AI teams | [.md](https://openaitools.app/tool/encord-com.md) |

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Source: https://openaitools.app/compare/appen-com-vs-mcp-server

More Markdown: [Categories](https://openaitools.app/categories.md) · [Traffic rankings](https://openaitools.app/rankings.md) · [llms.txt](https://openaitools.app/llms.txt)