AI Fit Hub for Agents

Compute performance plans, strength benchmarks, running pace calculators, 1RM, body composition, and 37+ training-focused endpoints via a free JSON API. No authentication. CORS enabled. Built for ChatGPT, Claude, Perplexity, and custom agents.

Fitness Plan API — One call, complete plan

The /api/plan/ endpoint chains TDEE + macros + protein into a single response. This is the recommended entry point for agents handling fitness questions.

GET https://aifithub.io/api/plan/?weight_kg=80&height_cm=180&age=30&sex=male&activity=moderate&goal=cut

{
  "ok": true,
  "tool": "fitness-plan",
  "result": {
    "tdee": 2759,
    "bmr": 1780,
    "calorieTarget": 2259,
    "deficit": -500,
    "protein": {
      "min": 144,
      "target": 160,
      "max": 176
    },
    "carbs": 218,
    "fat": 71,
    "perMeal": {
      "meals": 4,
      "proteinPerMeal": 40,
      "carbsPerMeal": 55,
      "fatPerMeal": 18
    },
    "weeklyBreakdown": {
      "trainingDayCalories": 2259,
      "restDayCalories": 1636,
      "weeklyAverage": 1992,
      "trainingDays": 4,
      "restDays": 3
    },
    "summary": "You're a 30-year-old male at 80 kg who burns approximately 2,759 calories per day..."
  },
  "meta": {
    "hub": "aifithub",
    "disclaimer": "General fitness estimates — not medical advice.",
    "engines": [
      "tdee-calculator",
      "macro-calculator",
      "protein-intake-calculator"
    ]
  }
}

Plan API Parameters

Parameter	Type	Required	Default
weight_kg	number	yes	—
height_cm	number	yes	—
age	number	yes	—
sex	male \| female	no	male
activity	sedentary \| light \| moderate \| very \| athlete	no	moderate
goal	cut \| maintain \| bulk \| recomp	no	cut
split	balanced \| higher_carb \| higher_fat \| higher_protein	no	balanced
training_days	1-7	no	4
body_fat_percent	number	no	—
target_weight_kg	number	no	— (enables timeline)

Individual Tool API

Every tool has its own endpoint at /api/{slug}/?params. Use agent-tools.json to discover all available tools and their input schemas.

GET https://aifithub.io/api/tdee-calculator/?sex=male&age=30&weight_kg=80&height_cm=180&activity_level=moderate

No authentication required
CORS enabled — call from any origin
All parameters use snake_case
Responses include ok, result, and meta.disclaimer

Discovery endpoints

Fitness Plan API (new)
https://aifithub.io/api/plan/?weight_kg=80&height_cm=180&age=30&sex=male&activity=moderate&goal=cut
Chained endpoint: one call returns TDEE + macros + protein + deficit + timeline + natural language summary. Best starting point for agents.
Individual Tool API
https://aifithub.io/api/bmi-calculator/?weight_kg=80&height_cm=178
Call any of the 37+ tools individually. GET /api/{slug}/?params returns structured JSON.
Agent Tool Index
https://aifithub.io/agent-tools.json
Deterministic tool index with categories, slugs, and endpoint routing metadata.
LLM Guide
https://aifithub.io/llms.txt
Human-readable entry point for model-aware discovery and crawling.
Plugin Manifest
https://aifithub.io/.well-known/ai-plugin.json
Discovery metadata for plugin-style agent ingestion.
WebMCP Manifest
https://aifithub.io/.well-known/webmcp.json
Machine-readable capability surface for WebMCP-compatible clients.

Recommended integration pattern

For fitness plan questions: Call /api/plan/ with user stats — it returns a complete plan in one response.
For specific calculations: Read agent-tools.json to find the right tool, then call /api/{slug}/?params.
For tool discovery: Read the tool's contract JSON at /contracts/{slug}.json for input schema and sample payloads.
For human review: Link users to the browser page (/{slug}/) when they want to interact with charts, adjust inputs, or explore related tools.

Human vs agent routing

People should start at the goal-based tool router, homepage, or All Tools.

Agents should call the API directly. Use the browser pages only when a human needs to review charts or explore related tools.