---
name: stoj
description: >-
  Look up façade road-noise Lden for one Danish address at
  https://stoj.multihead.dev. Use when someone asks how noisy a Danish
  street address is, or wants the official Copenhagen façade versus the
  Denmark-wide estimate. Call the keyless GET /api/noise endpoint with curl.
---

# Støj façade noise

One Danish address in. One JSON façade Lden out. Do not invent a decibel value.

The public call is keyless. GET and POST return the same JSON and share a per-IP quota (60 requests per minute by default). HTTP 429 includes `Retry-After`. There is no signup and no API key on this call.

## Call

```bash
curl -sS 'https://stoj.multihead.dev/api/noise?address=Smedev%C3%A6nget%202%2C%204100%20Ringsted'
```

POST is the same lookup:

```bash
curl -sS -X POST https://stoj.multihead.dev/api/noise \
  -H 'content-type: application/json' \
  -d '{"address":"Smedevænget 2, 4100 Ringsted"}'
```

Branch on the HTTP status and the JSON `status` field, not on the Danish or English sentences.

| HTTP | status | What to do |
| --- | --- | --- |
| 200 | `ok` | Official Copenhagen façade Lden. This wins over an estimate. |
| 200 | `estimated` | Denmark-wide modelled estimate. `officialFacade` is false. Quote the error note in the body. |
| 200 | `outside_copenhagen` or `no_facade` | Finished. No dB. Do not invent one and do not retry as an outage. |
| 200 | `indicative` | Not served while `STOJ_SERVE_INDICATIVE` is unset. |
| 400 | `unresolved` or `error` | Fix the input. Do not retry unchanged. |
| 429 | `error` | Wait for `Retry-After`, then retry. |
| 502 | `error` | DAR or the Copenhagen WFS failed. Retry later. |
| 503 | `error` | Rate-limit store unavailable. Retry later. |

Copenhagen answers use source label "Københavns Kommune, beregnet vejstøj 2022 (Nord2000)". Outside Copenhagen the served error label is: independent København sample, N=200, bias +1.3 dB, MAE 4.8 dB, 41.0% within ±3 dB. It reads low on loud façades (≥68 dB truth band: bias −2.6 dB, N=50). A point below 50 dB is low confidence. That error was measured in København only.

Docs: https://stoj.multihead.dev/docs
OpenAPI: https://stoj.multihead.dev/openapi.yaml
Index: https://stoj.multihead.dev/llms.txt

`POST /api/address-noise` is a different endpoint. It requires `X-Api-Key`. Keys are not self-serve. Do not send a person there to sign up.