Nummeropslag API
Public Partner API + MCP server for Danish phone-number lookup, caller-ID and spam/trust signals.
Identify who is calling from a Danish number: company from the official CVR register, telecom operator, number type, and a spam/trust verdict based on anonymous user reports. Powered by official open data β not scraping. Use it from any HTTP client, or plug the MCP server straight into Claude and other AI agents.
π Service: nummeropslag.dk Β· π Get a key: /api-noegle Β· π API reference: Redoc Β· π§ͺ Live sandbox: /api-reference Β· π€ MCP
This repository contains only public API docs, the OpenAPI spec, client examples and the MCP server. The backend source is private.
Authentication
All endpoints require an API key, sent in the X-API-Key header:
X-API-Key: npk_your_key_here
Each key has a plan, a set of scopes (lookup, spam, operator) and a request quota.
Check your key status any time via GET /api/v1/partner/me.
Base URL: https://nummeropslag.dk/api/v1
Endpoints
| Method | Endpoint | Scope | Description |
|---|---|---|---|
| GET | /partner/lookup/{e164} | lookup | Full lookup β operator, CVR companies, spam/trust signals |
| GET | /partner/spam/{e164} | spam | Compact spam/trust verdict only |
| GET | /partner/operator/{e164} | operator | Telecom operator + number type |
| GET | /partner/search?q= | lookup | Search companies by name (CVR) |
| GET | /partner/me | β | Your key status: plan, scopes, quota/usage |
{e164} accepts an 8-digit Danish number or full E.164 β e.g. 33633363 or +4533633363.
Full machine-readable contract: openapi/openapi.yaml Β· openapi/openapi.json.
Quick start
export NUMMEROPSLAG_API_KEY=npk_your_key_here
curl -H "X-API-Key: $NUMMEROPSLAG_API_KEY" \
https://nummeropslag.dk/api/v1/partner/spam/33633363
Client examples
Ready-to-run, dependency-free clients in examples/:
| Language | File | Run |
|---|---|---|
| Bash / curl | examples/curl.sh | ./curl.sh 33633363 |
| Python (stdlib) | examples/python_client.py | python3 python_client.py 33633363 |
| Node.js 18+ | examples/node_client.js | node node_client.js 33633363 |
| PHP | examples/php_client.php | php php_client.php 33633363 |
All read the key from the NUMMEROPSLAG_API_KEY environment variable.
Workflow integrations
Use Nummeropslag as native nodes and tools in popular automation and AI workflow builders:
| Platform | Integration | Location |
|---|---|---|
| n8n | Community node with five operations and AI Tool support | integrations/n8n |
| Dify | Installable tool plugin for Workflows, Chatflows and Agents | integrations/dify |
| Langflow | Custom component with Tool Mode support | integrations/langflow |
| Flowise | Ready-to-paste Custom Tool functions and schemas | integrations/flowise |
The integrations store the API key in each platform's credential/secret system
and send queries only to https://nummeropslag.dk.
MCP server (AI agents) π€
Give your AI agent (Claude Desktop, Claude Code, or any Model Context Protocol client)
direct access to Danish phone-number data. The server in mcp/ wraps the Partner API
as MCP tools β same official data, same privacy rules (no names of private individuals).
One-click desktop installation
Download the latest nummeropslag-mcp-*.mcpb bundle from
GitHub Releases, open it with a
compatible desktop client, and enter your Nummeropslag API key when prompted. The bundle uses
the managed uv runtime, so users do not need to install Python dependencies manually.
The canonical registry identifier is io.github.andrey-tut/nummeropslag.
Docker
The same stdio server is published as a public OCI image:
docker run --rm -i \
-e NUMMEROPSLAG_API_KEY=npk_your_key_here \
ghcr.io/andrey-tut/nummeropslag-mcp:latest
MCP calls are metered against a separate MCP quota (not your REST quota); the server sends
X-Client: mcp automatically.
Tools
| Tool | Description |
|---|---|
lookup_number(number) | Full record: company (CVR), operator, spam/trust, comments |
check_spam(number) | Compact spam/scam verdict (caller-ID style) |
get_operator(number) | Operator + number type only (cheapest) |
search_businesses(query, limit) | Find Danish companies by name (CVR) |
api_status() | Your key's scopes + quota usage |
Setup β via PyPI (recommended)
pip install nummeropslag-mcp # or: uvx nummeropslag-mcp
export NUMMEROPSLAG_API_KEY=npk_your_key_here # https://nummeropslag.dk/api-noegle
nummeropslag-mcp # stdio transport
Add to Claude Desktop (claude_desktop_config.json) or Claude Code (.mcp.json):
{
"mcpServers": {
"nummeropslag": {
"command": "nummeropslag-mcp",
"env": { "NUMMEROPSLAG_API_KEY": "npk_your_key_here" }
}
}
}
pip install "mcp[cli]" httpx
python mcp/server.py
β¦and use "command": "python", "args": ["/absolute/path/to/nummeropslag-api/mcp/server.py"] in the config above.
Restart your client, then ask e.g. "Is +45 70 10 20 30 spam?" or "Who owns 33 63 33 63?".
Errors
Errors use a consistent envelope:
{ "error": { "code": "forbidden", "message": "β¦", "details": {} } }
Common codes: unauthorized (missing/invalid key), forbidden (scope not allowed),
rate_limited (quota exceeded), not_found.
Data & privacy
- Core data: official CVR (companies + production units) and the Danish number plan (SDFI, CC0).
- Spam verdicts use k-anonymity β a public "spam" label requires several independent reports.
- Names of private individuals are never exposed. Contacts are never uploaded (GDPR-compliant).
Privacy Policy
The MCP server sends only the phone number or business query requested by the user to the first-party Nummeropslag API. It does not read conversations, files, contacts, or call logs. See the full Nummeropslag privacy policy for data collection, use, retention, sharing, and contact information.
License
The client examples and OpenAPI spec in this repository are released under the MIT License (see LICENSE) β copy and adapt them freely. The Nummeropslag API service itself and its data are proprietary; use is governed by the terms at nummeropslag.dk.