DemiSignal

DemiSignal (operated by Demi Solutions OÜ) is an email-authentication checking and monitoring service at demisignal.com. It runs free scans of a domain's published SPF, DKIM, DMARC, MX, BIMI and MTA-STS records, offers free SPF/DMARC/DKIM generators, an SPF flattener and a DMARC report analyzer, and sells paid plans (Starter, Pro, Agency) that collect DMARC aggregate reports to show sending sources, authentication results and change alerts. It also publishes a remote MCP server (com.demisignal/mcp in the MCP registry) so AI assistants can check domains and generate records.

DemiSignal is listed with 2 APIs on the APIs.io network. Tagged areas include Company, Email Authentication, DMARC, SPF, and DKIM.

DemiSignal’s developer surface includes authentication, API reference, getting-started guide, documentation, pricing, support, and 16 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

36.5/100 thin Agent 9/100 agent aware Full breakdown ↓
scored 2026-11-06 · rubric v0.27.0 · Show this score on your site →

AccessFreemiumSelf serve⚡ Free to try

2 APIs 1 MCP Servers

Company Email Authentication DMARC SPF DKIM Email Security DNS Domain Monitoring MCP

Kin Score

Kin Score How this is scored →
scored 2026-11-06 · rubric v0.27.0

Composite quality — 36.5/100 · thin

Contract Quality 0.0 / 21

Developer Ergonomics 7.7 / 17

Access Clarity 13.0 / 17

Operational Transparency 3.5 / 11

Contract Governance 0.0 / 10

Discoverability 5.5 / 9

Regulatory Posture 3.8 / 15

Agent readiness — 9/100 · agent aware

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 0 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Well-Known Document 0 / 5

Pagination 5 / 5

Distinct Operations 3 / 3

MCP Tool Quality 6 / 6

Regulatory Posture applies to this provider. Its tags matched the Horizontal (data, software, accessibility, platform) regime, so Regulatory Posture carries 15 points of the composite. If this regime is wrong for your business, say so on your provider repo — the applicability map is public and we will correct it.

Create-or-Update Ergonomics could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

The six quality facets above are damped to 85 points between them, because the conditional facet above carries the other 15. That is why each facet's contribution is shown against a damped maximum: raising a quality facet moves the composite by 85% of its nominal weight, not 100%. The full arithmetic is at apis.io/rating/.

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Agent readiness — checks not met, largest first (exact, from this profile):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented)
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes
A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link

10 more unmet checks in the Agent Readiness table above.

Kin Score — facets with the most composite points still available (weight × headroom):

Contract Quality scores 0.0 — up to +25.0 composite points
Contract Governance scores 0.0 — up to +12.0 composite points
Developer Ergonomics scores 45.2 — up to +11.0 composite points

Each check links to what satisfies it. Publish the artifact, or tell us where it already lives, and the score moves on the next scoring run.

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. Every facet and dimension name above is a link: it opens that measurement's own page — what it means, the exact checks that feed it, how the whole catalog distributes on it, and the providers at the top of it. This rating is computed from the provider profile at artifacts.apis.io/demisignal-com/apis.yml: open an issue on github.com/api-evangelist/demisignal-com to ask a question or point us at an artifact you publish. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

Standards implemented 1

Standards this provider implements or carries. De facto ones are profiled and measured by the API Commons; formal ones come from the standards directory and are linked by the provider's own tags. The evidence column says how each claim was established — not that it was made.

Model Context Protocol (MCP)

measured — observed by APIs.io (documented)

APIs 2

Individual APIs this provider publishes, each with its own machine-readable definition.

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, SP...

DemiSignal MCP Server

Remote MCP server over streamable HTTP at https://demisignal.com/mcp with three read-only tools (check_domain, generate_spf_record, generate_dmarc_record); usable with no accoun...

MCP Servers 1

Model Context Protocol servers that expose these APIs to AI agents.

DemiSignal MCP Server

Email authentication tools for a domain. check_domain looks up the domain's live DNS and grades its DMARC, SPF, DKIM, MX, BIMI and MTA-STS records. generate_spf_record and gener...

MCP SERVER

DemiSignal API pricing

Prices published by DemiSignal.

Plan	Price
Free one-off domain scan	No account. No card.
Starter	$19/ month
Pro	$49/ month
Business	$99/ month

Plan details, limits and sources →

Rate limits

Free API key monthly checks: A free API key gives your agent or script 100 new checks a month of its own.
Keyless shared daily allowance: Without a key, everyone using the server shares one daily allowance of new checks.

Rate-limit details →

Pricing Plans 1

Published pricing tiers and plan structures.

Demisignal Com Plans Pricing

4 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Demisignal Com Rate Limits

2 limits

RATE LIMITS

JSON Schema 6

Standalone JSON Schema definitions for this provider's data models.

check_domain input

2 properties

JSON SCHEMA

check_domain output

10 properties

JSON SCHEMA

generate_dmarc_record input

6 properties

JSON SCHEMA

generate_dmarc_record output

4 properties

JSON SCHEMA

generate_spf_record input

7 properties

JSON SCHEMA

generate_spf_record output

6 properties

JSON SCHEMA

Examples 1

Example request and response payloads for these APIs.

Demisignal Com Check Unauthenticated 401

1 fields

EXAMPLE

Security Posture 3

Authentication, domain security, vulnerability disclosure, and trust-center signals.

Demisignal Com Authentication

2 schemes

SECURITY

Demisignal Com Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Demisignal Com Vulnerability Disclosure

security.txt · contact published

SECURITY

Resources

Get Started 2

Portal, sign-up, and the first successful call

GettingStarted

GettingStarted

Login

Documentation 2

Reference material describing how the API behaves

APIReference

APIReference

Documentation

Documentation

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

MCPServer

MCPServer

WellKnown

WellKnown

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Conventions

Conventions

Lifecycle

Lifecycle

Access & Security 5

Authentication, authorization, and security posture

Authentication

Authentication

SecurityTxt

SecurityTxt

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Security

Security

Operate 2

Status, limits, changes, and where to get help

RateLimits

RateLimits

Support

Support

Commercial 4

Pricing, plans, and the legal terms of use

Plans

Pricing

TermsOfService

PrivacyPolicy

Company 1

The organization behind the API

Website

Website

Other 2

Properties that don't map to a standard resource type

Hosts

Hosts

Vendors

Vendors

Source (apis.yml)

aid: demisignal-com
name: DemiSignal
description: DemiSignal (operated by Demi Solutions OÜ) is an email-authentication checking and monitoring service at demisignal.com.
  It runs free scans of a domain's published SPF, DKIM, DMARC, MX, BIMI and MTA-STS records, offers free SPF/DMARC/DKIM generators,
  an SPF flattener and a DMARC report analyzer, and sells paid plans (Starter, Pro, Agency) that collect DMARC aggregate reports
  to show sending sources, authentication results and change alerts. It also publishes a remote MCP server (com.demisignal/mcp
  in the MCP registry) so AI assistants can check domains and generate records.
url: https://artifacts.apis.io/demisignal-com/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-05 (modular-v1; was harvest)
accessModel:
  pricing: freemium
  onboarding: self-serve
  trial: false
  try_now: true
  public: false
  gated: none
  gated_source:
  - onboarding
  label: Freemium · Self-serve signup
  confidence: high
  probe_state: covered
  source:
  - plans
  - authentication
  - rate-limits
  - security
  generated: '2026-11-06'
  method: derived
specificationVersion: '0.20'
created: '2026-11-05'
modified: '2026-11-05'
tags:
- Company
- Email Authentication
- DMARC
- SPF
- DKIM
- Email Security
- DNS
- Domain Monitoring
- MCP
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
image: https://demisignal.com/social/demisignal-og.png?v=7a76ed9752f9
common:
- type: RateLimits
  url: rate-limits/demisignal-com-rate-limits.yml
- type: Plans
  url: plans/demisignal-com-plans-pricing.yml
- type: Conventions
  url: conventions/demisignal-com-conventions.yml
- type: Authentication
  url: authentication/demisignal-com-authentication.yml
- type: Lifecycle
  url: lifecycle/demisignal-com-lifecycle.yml
- type: MCPServer
  url: mcp/demisignal-com-mcp.yml
- type: SecurityTxt
  url: well-known/demisignal-com-security.txt
- type: WellKnown
  url: well-known/demisignal-com-well-known.yml
- type: Hosts
  url: hosts/demisignal-com-hosts.yml
- type: Vendors
  url: vendors/demisignal-com-vendors.yml
- type: APIReference
  url: https://demisignal.com/guides/reference
- type: GettingStarted
  url: https://demisignal.com/guides/providers
- type: VulnerabilityDisclosure
  url: security/demisignal-com-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/demisignal-com-domain-security.yml
- type: Website
  url: https://demisignal.com/
- type: Documentation
  url: https://demisignal.com/guides
- type: Pricing
  url: https://demisignal.com/pricing
- type: Login
  url: https://demisignal.com/auth/login
- type: Support
  url: https://demisignal.com/contact
- type: Security
  url: https://demisignal.com/security
- type: TermsOfService
  url: https://demisignal.com/legal/terms
- type: PrivacyPolicy
  url: https://demisignal.com/legal/privacy
apis:
- 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
- aid: demisignal-com:demisignal-mcp-server
  name: DemiSignal MCP Server
  description: Remote MCP server over streamable HTTP at https://demisignal.com/mcp with three read-only tools (check_domain,
    generate_spf_record, generate_dmarc_record); usable with no account, or with a free dsk_ API key for a personal monthly
    allowance.
  humanURL: https://demisignal.com/tools/mcp-server
  baseURL: https://demisignal.com/mcp
  tags:
  - MCP
  - Email Authentication
  properties:
  - type: Documentation
    url: https://demisignal.com/tools/mcp-server
x-coverage:
  state: covered
  reason: identity-verified
  detail: Name, description, tags, image and link pointers verified from demisignal.com pages (title "| DemiSignal", footer
    "Demi Solutions OÜ"). /guides/reference is an email-authentication reference guide, not an API reference, so no APIReference
    pointer. /blog, /auth/signup, /guides/getting-started returned 404 and were not added.
  evidence:
  - url: https://demisignal.com/
    status: 200
  - url: https://demisignal.com/guides
    status: 200
  - url: https://demisignal.com/pricing
    status: 302
  - url: https://demisignal.com/auth/login
    status: 200
  - url: https://demisignal.com/contact
    status: 200
  - url: https://demisignal.com/security
    status: 200
  - url: https://demisignal.com/legal/terms
    status: 200
  - url: https://demisignal.com/legal/privacy
    status: 200
  - url: https://demisignal.com/tools/mcp-server
    status: 200
  - url: https://demisignal.com/blog
    status: 404
x-enrichment:
  date: '2026-11-05'
  status: enriched
  artifacts_added: 23
  pass: modular-v1
  engine: identity=anthropic,contract=anthropic,surfaces=anthropic,docs=anthropic,regulatory=anthropic

DemiSignal API — frequently asked questions

Does DemiSignal have an API?

Yes. APIs.io lists 2 APIs from DemiSignal, including DemiSignal Check API and DemiSignal MCP Server.

How do I authenticate with the DemiSignal API?

DemiSignal uses bearer-token authentication (2 schemes). The details are profiled on APIs.io as Demisignal Com Authentication.

How much does the DemiSignal API cost?

DemiSignal publishes its prices; its Free one-off domain scan plan is No account. No card. as of 2026-11-05. APIs.io lists 4 pricing plans for DemiSignal, with each plan's price, limits and inclusions under Pricing on this page.

Does DemiSignal have an MCP server?

Yes. APIs.io lists 1 MCP server for DemiSignal: Email authentication tools for a domain. check_domain looks up the domain's live DNS and grades its DMARC, SPF, DKIM, MX, BIMI and MTA-STS records. generate_spf_record and generate_dmarc_record build

Is the DemiSignal API ready for AI agents?

DemiSignal has a Kin Score of 36.5 out of 100 (thin) and an Agent Readiness score of 8.5 (agent-aware), scored by API Evangelist on 2026-11-06.

Work with this as data

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get_provider_operationsEvery operation across all of their OpenAPIs — one call instead of parsing every spec.
get_provider_toolsEvery MCP tool they ship, with the operation each wraps.
get_provider_evidenceHow each part of their score was established. Free — the basis for a claim should not sit behind it.
get_provider_ratingPRO — composite, band, trend and facet scores.
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.
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