Public API and Es MUF widget

Sked Chat publishes its propagation and activity data as a free, read-only JSON API and as a small widget you can put on a club or personal website. No key is needed.

Rules

Base address: https://skeds.sq3swg.com/api/v1/public/. Only GET; CORS is open (Access-Control-Allow-Origin: *), so you can call it from a browser.
At most about 1 request per second per IP address (bursts of 60 are fine); more returns 429 with Retry-After. The data changes every few minutes, so poll every 5–15 minutes and respect Cache-Control.
Credit the original sources when you show propagation data: hamqsl.com (N0NBH) for solar and band data, prop.kc2g.com / GIRO for ionosonde data.
Times are ISO 8601 in UTC; frequencies of spots are in kHz. The API is version 1; fields may be added, but existing ones will not change meaning without a new version.

`GET /api/v1/public/propagation`

Sporadic-E MUF per ionosonde, a Europe summary for 6 m / 4 m / 2 m, and solar and band data. Updated every 15 minutes; 503 for a minute after a server restart.

{
  "fetchedAt": "2026-10-26T10:36:00.000Z",
  "esHopKm": 2000,
  "esFactor": 5.38,
  "europe": {
    "highest": { "station": "Roquetes, Spain", "code": "EB040", "esMuf": 22, "foEs": 4, "ageMin": 7 },
    "bands": {
      "6m": { "thresholdMHz": 50, "stations": [] },
      "4m": { "thresholdMHz": 70, "stations": [] },
      "2m": { "thresholdMHz": 144, "stations": [] }
    }
  },
  "solar": { "sfi": 89, "sunspots": 25, "aIndex": 5, "kIndex": 1, "hf": [ … ], "vhf": [ … ], … },
  "ionosondes": [
    { "code": "EB040", "name": "Roquetes, Spain", "lat": 40.8, "lon": 0.5, "time": "…",
      "foEs": 4, "esMuf": 22, "foF2": 7.85, "mufF2": 27.8 }
  ]
}

esMuf is foEs × esFactor: the highest frequency a single esHopKm sporadic-E hop can carry over that ionosonde (an estimate – see the propagation page).

`GET /api/v1/public/rooms`

How busy the band rooms are. Counts only – no callsigns.

{
  "online": 12,
  "skedsToday": 7,
  "rooms": [ { "id": "144", "name": "144 MHz", "online": 8 }, { "id": "50", "name": "50 MHz", "online": 5 }, … ]
}

`GET /api/v1/public/spots?band=144&limit=50`

Recent DX cluster spots, newest first. band is a room id (50, 70, 144, 432, 1296, uwave, hf) or omitted for all; limit is 1–200 (default 50). Only spots from the DX cluster network are published here; spots that users post on Sked Chat stay inside the chat.

{
  "band": "144",
  "spots": [
    { "time": "…", "freqKHz": 144300, "dx": "DL1XYZ", "spotter": "SP5ABC", "comment": "JO62 tropo 59", "bands": ["144"] }
  ]
}

Shows the highest sporadic-E MUF in Europe and whether 6 m, 4 m or 2 m Es is possible, and refreshes itself every 5 minutes. Paste this into your page:

<iframe src="https://skeds.sq3swg.com/widget/es" width="260" height="150"
        style="border:0;border-radius:8px" title="Sporadic-E MUF now" loading="lazy"></iframe>

Options, added to the address: ?lang=pl for Polish, ?theme=light or ?theme=dark to fix the colours (otherwise it follows the visitor's system setting), e.g. /widget/es?lang=pl&theme=light.

Preview:

Questions

Write to adam@sq3swg.com if you build something with it, need other data, or need a higher limit.

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