SpecialistConnects teams directly with verified human participants for preference tuning and studies, but lacks managed end-to-end labeling pipelines.

Appen records 665,840 monthly visits with +0.2% month-over-month growth and Contact for Pricing pricing. Models.dev records 200,451 monthly visits with -3.9% growth and Free pricing.

Open-source database of AI models, prices and capabilities
| Dimension / Metric | ![]() | ![]() |
|---|---|---|
| Official Domain | appen.com | models.dev |
| Pricing Model | Contact for Pricing | Free |
| Monthly Visits | 665.84K (665,840) | 200.45K (200,451) |
| MoM Traffic Delta |
| +1.1K (+0.2%) |
| -8.17K (-3.9%) |
| Primary Market & Share | 🇺🇸 United States (22%) | 🇨🇳 China (23%) |
|---|
| Direct Visits / mo | 238.31K | 136.32K |
|---|
| User Rating | 4.4 | 4.4 |
|---|
| Supported Platforms | Website | Website |
|---|

Human-validated training data and evaluation services for frontier AI models
Chain-of-thought reasoning traces, SME-level RLHF, supervised fine-tuning demonstrations and adversarial red teaming for the most capable models.
Golden trajectories, RL environment design, failure-mode taxonomies and software-engineering-driven deep evaluation for autonomous agents.
Multilingual ASR and conversational speech data, expressive TTS annotation, vision-language model training data, video action labelling and voice-agent evaluation.
LiDAR point-cloud labeling, multi-camera sensor fusion, robot demonstration trajectories, world-model rollouts and embodied interaction logs.

Open-source database of AI models, prices and capabilities
Every model uses a consistent provider/model format so the same model across providers can be compared directly.
Side-by-side context window, output limit, reasoning, tool calling, structured output, and temperature support.
Input and output prices per million tokens listed alongside release and update dates.
Covers closed flagship APIs and open-weight models from many labs in one sortable catalogue.
SpecialistConnects teams directly with verified human participants for preference tuning and studies, but lacks managed end-to-end labeling pipelines.


Blends custom software with dedicated human expert teams to handle complex operations, but operates as a bespoke service.


Combines robust data labeling tools with automated workflows, but focuses more on software tooling than managed human workforces.
Provides enterprise-grade AI training data and model evaluation at massive scale, but often with higher enterprise pricing.

Delivers advanced multimodal data curation and annotation infrastructure, but requires your own annotation workforce for labeling tasks.

SpecialistAgent observability, evaluation, and continuous improvement for production AI
SpecialistThe multimodal data layer for computer vision and physical AI teams

SpecialistIncludes model pricing trackers and developer news alongside tools directories, but less focused on raw API specs.
Offers pre-packaged AI training datasets and custom data collection services, but with a smaller global crowd than Appen.

Free / Open-sourceProvides a flexible open-source annotation platform for self-hosting, but lacks Appen's managed enterprise human workforce services.


Supplies expert human annotators for specialized training and evaluation datasets, but operates at a smaller scale.

SpecialistCatalogues and compares AI infrastructure tools and services across categories, but lacks deep per-token pricing tables.
SpecialistConnects teams directly with verified human participants for preference tuning and studies, but lacks managed end-to-end labeling pipelines.
Blends custom software with dedicated human expert teams to handle complex operations, but operates as a bespoke service.
Combines robust data labeling tools with automated workflows, but focuses more on software tooling than managed human workforces.
Provides enterprise-grade AI training data and model evaluation at massive scale, but often with higher enterprise pricing.
Delivers advanced multimodal data curation and annotation infrastructure, but requires your own annotation workforce for labeling tasks.
SpecialistAgent observability, evaluation, and continuous improvement for production AI
SpecialistThe multimodal data layer for computer vision and physical AI teams
SpecialistIncludes model pricing trackers and developer news alongside tools directories, but less focused on raw API specs.
Offers pre-packaged AI training datasets and custom data collection services, but with a smaller global crowd than Appen.
Free / Open-sourceProvides a flexible open-source annotation platform for self-hosting, but lacks Appen's managed enterprise human workforce services.
Supplies expert human annotators for specialized training and evaluation datasets, but operates at a smaller scale.
SpecialistCatalogues and compares AI infrastructure tools and services across categories, but lacks deep per-token pricing tables.