Sprocket Echo

Instant signal reflection — no fuss, pure Go.

POST /echo — bounce your JSON back

Your payload, right back at you. No transforms, no side-effects — just a clean bounce. Send any valid JSON and watch it echo in under a millisecond.

Try it live

curl -X POST /echo \
  -H "Content-Type: application/json" \
  -d '{"message":"Hello, sprocket!","count":42}'

Sample response

{
  "echo": {
    "message": "Hello, sprocket!",
    "count": 42
  },
  "meta": {
    "request_id": "req_3f8a7b",
    "elapsed_ms": 0.312,
    "sprocket": "🔄",
    "timestamp": "2025-03-15T10:23:04.123456Z"
  }
}

Method not allowed

This gear only turns for POST requests. Any other method — GET, PUT, DELETE, PATCH — gets a polite but firm refusal.

Sample 405 response

{
  "type": "about:blank",
  "title": "Method Not Allowed",
  "status": 405,
  "detail": "🚫🔧 This signal path is locked — only POST allowed.",
  "sprocket": "🚫🔧"
}

Malformed JSON

Syntax error? We'll tell you exactly where it hurts. The byte offset is extracted directly from Go's JSON parser.

Sample 400 response

{
  "type": "about:blank",
  "title": "Bad Request",
  "status": 400,
  "detail": "🔧 Your payload slipped a tooth — check byte 23.",
  "sprocket": "🔧"
}

Service endpoints

POST /echo — bounce your JSON back with meta

GET /healthz — liveness probe

GET /health — healthcheck

GET /metrics — Prometheus telemetry