# actuatorlist

> Open, spec-level directory of robot actuators (QDD motors, integrated joints, smart servos, harmonic and cycloidal reducers) and the robots that use them.

The catalog holds 80 actuators from 31 brands in 6 categories, plus 22 robots with the motor in each joint. It is free, public and read-only: no account, API key or payment is needed for the site, the REST API or the MCP server. Data last updated 2026-11-01.

## When to use actuatorlist

Reach for actuatorlist when a user needs numbers about robot joint actuators:

- Pick an actuator for a quadruped leg, humanoid joint or robot arm given a torque, weight or budget target (filter by use_case, min_peak_torque_nm, max_weight_g, max_price_usd).
- Rank actuators by torque density, price per Nm, backlash or speed.
- Compare two or more specific actuators side by side (peak and rated torque, gear ratio, weight, voltage, bus, encoder, price).
- Find which motors a real robot uses in each joint, or which robots use a given actuator.
- Look up one actuator's datasheet-level specs with source links before recommending it.

How to call it:

- MCP: connect a Streamable HTTP client to https://actuatorlist.com/mcp (no auth). Tools: search_actuators, get_actuator, list_actuator_categories, list_brands, compare_actuators, recommend_actuators, list_robots, get_robot, find_robots_using_actuator, get_humanoid_joints, humanoid_joint_requirements, arm_holding_torque, list_companies, get_company, list_sites, get_metal_supply, get_metal_prices, list_policy_measures.
- REST: GET https://actuatorlist.com/api/v1/actuators?use_case=quadruped_leg&sort=torque_density_nm_per_kg returns JSON, no key needed.
- Markdown: append .md to any page URL, or send Accept: text/markdown.

## Connect

- MCP server: `https://actuatorlist.com/mcp` (Streamable HTTP, server name actuatorlist, anonymous and read-only)
- Docs MCP server: `https://actuatorlist.com/mcp/docs` (the site documentation over MCP, same terms)
- [MCP server card](https://actuatorlist.com/.well-known/mcp/server-card.json): tools and endpoint before you connect
- [OpenAPI description](https://actuatorlist.com/openapi.json): machine-readable REST contract
- [API reference](https://actuatorlist.com/docs/api): endpoints, parameters and examples
- [API index](https://actuatorlist.com/api): JSON list of every endpoint
- [auth.md](https://actuatorlist.com/auth.md): why no credentials are needed

## Docs for agents

- [llms-full.txt](https://actuatorlist.com/llms-full.txt): the whole catalog as text in one fetch
- [agents.md](https://actuatorlist.com/agents.md): agent guide: when to use, MCP, REST, limits
- [pricing.md](https://actuatorlist.com/pricing.md): free plan, rate limit and license
- [Actuators section](https://actuatorlist.com/actuators/llms.txt): one line per actuator with its markdown spec sheet
- [Robots section](https://actuatorlist.com/robots/llms.txt): robots and the motors in each joint
- [API docs section](https://actuatorlist.com/docs/llms.txt): REST endpoints and discovery documents
- [Agent skill](https://actuatorlist.com/.well-known/agent-skills/actuatorlist/SKILL.md): SKILL.md teaching an agent to use the API and MCP server

## Catalog pages (markdown)

- [Home](https://actuatorlist.com/index.md): overview, top actuators by torque density, FAQ
- [Actuators](https://actuatorlist.com/actuators.md): every actuator in one table, plus categories
- [Robots](https://actuatorlist.com/robots.md): robots with per-joint motors

## Engineering guides and tools (markdown)

- [Humanoid robot actuators](https://actuatorlist.com/guides/humanoid-robot-actuators.md): static torque per joint (pose and arithmetic shown) and catalog actuators that reach it; same data from the MCP tool humanoid_joint_requirements and, on the page, WebMCP tools get_humanoid_joint_requirements and show_humanoid_joint
- [Robot actuator selection guide](https://actuatorlist.com/guides/robot-actuator-selection.md): efficiency, thermal duty, precision and sim2real checks
- [Motor torque calculator](https://actuatorlist.com/tools/motor-torque-calculator.md): torque, power and speed relation, units and worked examples
- [Robot arm torque calculator](https://actuatorlist.com/tools/robot-arm-torque-calculator.md): static holding torque per joint; same model from the MCP tool arm_holding_torque and, on the page, WebMCP tools calculate_arm_holding_torque, set_arm_model and select_arm_joint

## Supply chain (markdown)

- [Magnet metals](https://actuatorlist.com/metals.md): Nd, Pr, Dy, Tb, Sm and Co: country share at each stage from mine to magnet, USGS reserves and years of supply, cited price history and the events behind it; same data from the MCP tools get_metal_supply and get_metal_prices
- [Actuator chain policy](https://actuatorlist.com/policy.md): export controls, tariffs, subsidies and standards from mine to robot with status history and primary sources; MCP list_policy_measures, REST /api/v1/policy, Atom feed /policy/feed.xml

## About

- [About](https://actuatorlist.com/about.md): who runs the catalog and how data is verified
- [Contact](https://actuatorlist.com/contact.md): report wrong data or contribute via GitHub
- [Privacy](https://actuatorlist.com/privacy.md): no accounts, cookies or analytics

## Optional

- [Sitemap](https://actuatorlist.com/sitemap.xml): every indexable URL
- [JSON Lines feed](https://actuatorlist.com/feeds/actuators.jsonl): one actuator object per line
- [Source repository](https://github.com/Miyamura80/getactuators): dataset (CC BY 4.0), site code (MIT License) and AGENTS.md