Developers: API and MCP Server

A free, read-only API for 240+ curated off-road trails, 8,100+ campgrounds, and the same 13 calculators the site runs. Built for AI agents as well as apps: point Claude, ChatGPT, or any MCP client at our server and it can plan a trip, size tires, or budget a build. Every response includes the canonical 4x4playground.com URL for the data, and we ask that you show it.

Get a free API key

Limits: 1,000 requests per key per day and 60 per minute. We log only the key prefix, endpoint, and response time. We never share your email.

Quick start

curl "https://yszawajuybghfvfngzyg.supabase.co/functions/v1/api/trails/search?state=UT&difficulty=Hard&limit=3" \
  -H "x-api-key: YOUR_KEY"

curl -X POST "https://yszawajuybghfvfngzyg.supabase.co/functions/v1/api/tools/gear-ratio" \
  -H "x-api-key: YOUR_KEY" -H "Content-Type: application/json" \
  -d '{"stock_tire_diameter":31,"new_tire_diameter":35,"current_gear_ratio":3.73}'

Send your key as x-api-key or Authorization: Bearer. Every response has data, a source object with the canonical URL, and a disclaimer. Lists take limit (max 50) and offset and return total. Distances are in miles, weights in pounds, pressures in PSI.

Endpoints

GET /trails/searchSearch trails by keyword, state, difficulty (Easy, Moderate, Hard, Expert), type, or coordinates
GET /trails/{slug}One trail with nearby trails and the three closest campgrounds
GET /campgrounds/searchSearch campgrounds by keyword, state, amenities, or distance
GET /campgrounds/{state}/{slug}One campground with nearby trails and campgrounds
POST /tools/tire-sizeCompare two tire sizes
POST /tools/gear-ratioRecommend an axle ratio after a tire change
POST /tools/wheel-fitmentOffset to backspacing, poke, and rubbing risk
POST /tools/bolt-patternBolt pattern, hub bore, lug spec, torque
POST /tools/mpg-impactFuel economy loss from tires, lift, and racks
POST /tools/speedometerSpeedometer and odometer error
POST /tools/build-budgetPhased build plan against a budget
POST /tools/lift-costParts and labour cost for a lift
POST /tools/gear-loadoutOverlanding gear checklist with price tiers
POST /tools/payloadPayload and GVWR headroom
POST /tools/air-downTire pressure by terrain with contact patch gain
POST /tools/recovery-gearRope, winch, and recovery point ratings
POST /tools/trail-matchScore trails against a specific rig

Full schema: /openapi.json or the live spec.

MCP server

The MCP server speaks JSON-RPC 2.0 over streamable HTTP and exposes all 13 calculators and 4 matchmakers with the same key. Add it to any MCP client:

{
  "mcpServers": {
    "4x4-playground": {
      "url": "https://yszawajuybghfvfngzyg.supabase.co/functions/v1/mcp-api",
      "headers": { "x-api-key": "YOUR_KEY" }
    }
  }
}

Tools: find_trails, get_trail, find_campgrounds, get_campground, calculate_tire_size, calculate_gear_ratio, calculate_wheel_fitment, lookup_bolt_pattern, estimate_mpg_impact, calculate_speedometer_error, plan_build_budget, estimate_lift_cost, build_gear_loadout, calculate_payload, calculate_air_down_psi, recommend_recovery_gear, match_trails_to_vehicle. Agent notes live at /connectors/muse.txt.

Fair use

The API is read-only and free. Cache what you can, cite the source URL in anything you publish or show to a user, and treat calculator output as a planning estimate rather than an engineering specification. Trail conditions and campground rules change, so always check with the land manager before a trip.