DemiSignal

DemiSignal Check API

Free HTTP API documented on the DemiSignal MCP server page; GET /api/v1/check?domain= returns as JSON the same email-authentication check as the check_domain MCP tool (DMARC, SPF, DKIM, MX, BIMI and MTA-STS graded from public DNS). Requires a free API key (prefix dsk_) sent as Authorization Bearer; 100 new checks a month per key.

GitHub

Documentation

📖
Documentation
https://demisignal.com/tools/mcp-server

Other Resources

🔗
APIsJSON
https://artifacts.apis.io/demisignal-com/apis.yml

Work with this as data

Every API here is available over the APIs.io API and to AI agents over MCP.

MCP server

One button, every client — Claude, Cursor, VS Code and the rest.

https://apis.io/mcp

Tools for apis

7 MCP tools reach this
  • find_apisBrowse and filter every API in the catalog.
  • get_api_artifactsOne API's artifacts, grouped by type.
  • get_openapiThe primary OpenAPI for this API.
  • find_similar_apisAPIs that look like this one.
  • apis_io_searchSTART HERE — APIs, providers and tags for one query, each with its total.
  • resolveTurn a domain, URL or GitHub org into the provider it belongs to.
  • find_cohortsEvery scored population of providers in the catalog.
All 92 tools →

Call it yourself

curl for this page
This API 
curl "https://apis.io/api/v1/apis/demisignal-com:demisignal-check-api"
All apis 
curl "https://apis.io/api/v1/apis?limit=25"

Calls without X-API-Key need no key. Calls with it need a paid plan — get a key.

Get an API key

Free tier, no form to fill in. Signing in shares your email address with us — we store it to create your key and to recognise you if you sign in with another provider. See our Privacy Policy and Terms.

GitHub Google LinkedIn

A second provider on the same verified email joins the account you already have.

API entry from apis.yml

apis.yml Raw ↑ 
aid: demisignal-com:demisignal-check-api
name: DemiSignal Check API
description: Free HTTP API documented on the DemiSignal MCP server page; GET /api/v1/check?domain= returns
  as JSON the same email-authentication check as the check_domain MCP tool (DMARC, SPF, DKIM, MX, BIMI
  and MTA-STS graded from public DNS). Requires a free API key (prefix dsk_) sent as Authorization Bearer;
  100 new checks a month per key.
humanURL: https://demisignal.com/tools/mcp-server
baseURL: https://demisignal.com/api/v1
tags:
- Email Authentication
- DMARC
- SPF
- DKIM
properties:
- type: Documentation
  url: https://demisignal.com/tools/mcp-server