# DemiSignal Check API

**Canonical:** https://apis.io/apis/demisignal-com/demisignal-check-api/  
**Provider:** DemiSignal — https://apis.io/providers/demisignal-com/  
**Base URL:** https://demisignal.com/api/v1  
**Documentation:** https://demisignal.com/tools/mcp-server

DemiSignal Check API is one of 2 APIs that [DemiSignal](https://apis.io/providers/demisignal-com/) publishes on the [APIs.io](https://apis.io/) network. Tagged areas include Email Authentication, DMARC, SPF, and DKIM. The published artifact set on APIs.io includes API documentation.

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.

## Machine-readable artifacts (2)

- **Documentation** — https://demisignal.com/tools/mcp-server
- **APIsJSON** — https://artifacts.apis.io/demisignal-com/apis.yml

## Other DemiSignal APIs (1)

- [DemiSignal MCP Server](https://apis.io/apis/demisignal-com/demisignal-mcp-server/)

## Tags

Email Authentication, DMARC, SPF, DKIM

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/apis/demisignal-com/demisignal-check-api/). The API's provider profile, Kin Score and agent-readiness rating are at https://apis.io/providers/demisignal-com/.