Exclaimer

Exclaimer is an email signature management platform used by IT, marketing, and sales teams to centrally create, deploy, and govern corporate email signatures across Microsoft 365, Microsoft Exchange, and Google Workspace. It manages signatures for more than 9 million email accounts, adding campaign banners, meeting-branding backgrounds, click-tracking analytics, directory synchronization with Azure AD and Google Directory, and role-based access control. Exclaimer publishes the Exclaimer Cloud API — a partner/distributor provisioning REST API documented at cloudapi.exclaimer.com with a machine- readable OpenAPI 3.0.1 definition covering subscriptions, MSP subscriptions, subscription users, resellers, end users, mailbox counts, subscription transfers and reference data. It operates a multi-region Exclaimer Cloud with a real-time status page and a strong security and compliance program (SOC 2 Type II, ISO 27001/27018, HIPAA, PCI DSS, CSA STAR, Cyber Essentials).

Exclaimer publishes 9 APIs on the APIs.io network, including End Users API, Mailboxes API, Miscellaneous API, and 6 more. Tagged areas include Company, Email, Email Signatures, Email Signature Management, and Microsoft-365.

Exclaimer’s developer surface includes pricing, engineering blog, signup flow, documentation, API reference, getting-started guide, support, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub

60.7/100 strong ▬ flat Agent 29/100 agent aware saas Full breakdown ↓
scored 2026-09-06 · rubric v0.19.0

AccessApproval

10 APIs

Company EmailEmail SignaturesEmail Signature Management Microsoft-365 Google Workspace Marketing Productivity Software-as-a-Service Security

Kin Score

Kin Score How this is scored →
scored 2026-09-06 · rubric v0.19.0

Composite quality — 60.7/100 · strong

Contract Quality 13.5 / 25

Developer Ergonomics 13.2 / 20

Access Clarity 18.4 / 20

Operational Transparency 6.8 / 13

Contract Governance 0.5 / 12

Discoverability 8.2 / 10

Agent readiness — 29/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 6 / 6

MCP Server 0 / 12

Machine-Readable Auth 10 / 10

Idempotency 0 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 7 / 7

Typed Event Surface 0 / 6

Agent Skills 5 / 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

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 github.com/api-evangelist/exclaimer: open an issue to ask a question, or submit a pull request to add artifacts. Submit an artifact on GitHub — free → Manage your own listing — the Influence plan, $499/mo →

APIs 9

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

Rate Limits 1

Documented rate limits and quota policies.

Get Started 3

Portal, sign-up, and the first successful call

SignUp

SignUp

DeveloperPortal

DeveloperPortal

GettingStarted

GettingStarted

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 3

MCP servers, agent skills, and machine-readable catalogs

AgentSkill

AgentSkill

WellKnown

WellKnown

LLMsTxt

LLMsTxt

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

Lifecycle

Lifecycle

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 6

Authentication, authorization, and security posture

Compliance

Compliance

TrustCenter

TrustCenter

Security

Security

VulnerabilityDisclosure

VulnerabilityDisclosure

SecurityTxt

SecurityTxt

DomainSecurity

DomainSecurity

Operate 5

Status, limits, changes, and where to get help

HelpCenter

StatusPage

Support

ChangeLog

Deprecation

Commercial 4

Pricing, plans, and the legal terms of use

Pricing

TermsOfService

PrivacyPolicy

Plans

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: exclaimer
name: Exclaimer
description: Exclaimer is an email signature management platform used by IT, marketing, and sales teams to centrally create,
  deploy, and govern corporate email signatures across Microsoft 365, Microsoft Exchange, and Google Workspace. It manages
  signatures for more than 9 million email accounts, adding campaign banners, meeting-branding backgrounds, click-tracking
  analytics, directory synchronization with Azure AD and Google Directory, and role-based access control. Exclaimer publishes
  the Exclaimer Cloud API — a partner/distributor provisioning REST API documented at cloudapi.exclaimer.com with a machine-
  readable OpenAPI 3.0.1 definition covering subscriptions, MSP subscriptions, subscription users, resellers, end users, mailbox
  counts, subscription transfers and reference data. It operates a multi-region Exclaimer Cloud with a real-time status page
  and a strong security and compliance program (SOC 2 Type II, ISO 27001/27018, HIPAA, PCI DSS, CSA STAR, Cyber Essentials).
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: true
  label: Hosted service · you call their endpoint
  confidence: high
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: approval
  trial: false
  try_now: false
  public: false
  label: Requires approval
  confidence: medium
  source: []
  generated: '2026-07-22'
  method: derived
image: https://exclaimer.com/img/og-image.jpg
url: https://raw.githubusercontent.com/api-evangelist/exclaimer/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- insight-partners
x-tier: enriched
x-tier-reason: 'Promoted from stub 2026-08-13: the Exclaimer Cloud API and its OpenAPI 3.0.1 were discovered and captured,
  with 22 artifacts wired.'
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-08-13'
tags:
- Company
- Email
- Email Signatures
- Email Signature Management
- Microsoft-365
- Google Workspace
- Marketing
- Productivity
- Software-as-a-Service
- Security
tags_raw:
- Company
- Email
- Email Signatures
- Email Signature Management
- Microsoft 365
- Google Workspace
- Marketing
- Productivity
- SaaS
- Security
apis:
- aid: exclaimer:exclaimer-end-users-api
  name: Exclaimer End Users API
  description: The End Users API from Exclaimer — 1 operation(s) for end users.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - End Users
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-end-users-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-mailboxes-api
  name: Exclaimer Mailboxes API
  description: The Mailboxes API from Exclaimer — 1 operation(s) for mailboxes.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Mailboxes
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-mailboxes-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-miscellaneous-api
  name: Exclaimer Miscellaneous API
  description: The Miscellaneous API from Exclaimer — 2 operation(s) for miscellaneous.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags: []
  tags_raw:
  - Miscellaneous
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-miscellaneous-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-msp-api
  name: Exclaimer MSP API
  description: The MSP API from Exclaimer — 4 operation(s) for msp.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - MSP
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-msp-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-reference-resources-api
  name: Exclaimer Reference Resources API
  description: The Reference Resources API from Exclaimer — 3 operation(s) for reference resources.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Reference Resources
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-reference-resources-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-resellers-api
  name: Exclaimer Resellers API
  description: The Resellers API from Exclaimer — 1 operation(s) for resellers.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Resellers
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-resellers-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-subscription-transfers-api
  name: Exclaimer Subscription Transfers API
  description: The Subscription Transfers API from Exclaimer — 3 operation(s) for subscription transfers.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Subscription Transfers
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-subscription-transfers-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-subscription-users-api
  name: Exclaimer Subscription Users API
  description: The Subscription Users API from Exclaimer — 4 operation(s) for subscription users.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Subscription Users
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-subscription-users-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
- aid: exclaimer:exclaimer-subscriptions-api
  name: Exclaimer Subscriptions API
  description: The Subscriptions API from Exclaimer — 13 operation(s) for subscriptions.
  humanURL: https://cloudapi.exclaimer.com/
  baseURL: https://cloudapi.exclaimer.com/exclaimerapi
  tags:
  - Subscription
  tags_raw:
  - Subscriptions
  properties:
  - type: OpenAPI
    url: openapi/exclaimer-subscriptions-api-openapi.yml
  - type: APIReference
    url: https://cloudapi.exclaimer.com/
  - type: Documentation
    url: https://cloudapi.exclaimer.com/
  - type: Authentication
    url: authentication/exclaimer-authentication.yml
  - type: Conventions
    url: conventions/exclaimer-conventions.yml
  - type: ErrorCatalog
    url: errors/exclaimer-problem-types.yml
  - type: DataModel
    url: data-model/exclaimer-data-model.yml
  - type: RateLimits
    url: rate-limits/exclaimer-rate-limits.yml
  - type: Sandbox
    url: sandbox/exclaimer-sandbox.yml
  - type: Conformance
    url: conformance/exclaimer-conformance.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Overlay
  url: overlays/exclaimer-cloud-api-overlay.yaml
- type: AgentSkill
  url: skills/_index.yml
- type: Website
  url: https://exclaimer.com/
- type: Pricing
  url: https://exclaimer.com/pricing/
- type: Blog
  url: https://exclaimer.com/blog/
- type: SignUp
  url: https://go.exclaimer.com/trial
- type: HelpCenter
  url: https://support.exclaimer.com/hc/en-gb
- type: TermsOfService
  url: https://exclaimer.com/legal/website-terms-of-use/
- type: PrivacyPolicy
  url: https://exclaimer.com/legal/privacy-policy/
- type: StatusPage
  url: https://status.exclaimer.com/
- type: Lifecycle
  url: lifecycle/exclaimer-lifecycle.yml
- type: Compliance
  url: https://exclaimer.com/product/security/
- type: TrustCenter
  url: security/exclaimer-trust-center.yml
- type: Security
  url: https://vdp.exclaimer.com/p/Welcome
- type: VulnerabilityDisclosure
  url: security/exclaimer-vulnerability-disclosure.yml
- type: SecurityTxt
  url: well-known/exclaimer-security.txt
- type: WellKnown
  url: well-known/exclaimer-well-known.yml
- type: DomainSecurity
  url: security/exclaimer-domain-security.yml
- type: DeveloperPortal
  url: https://cloudapi.exclaimer.com/
- type: Documentation
  url: https://support.exclaimer.com/hc/en-gb
- type: APIReference
  url: https://cloudapi.exclaimer.com/
- type: GettingStarted
  url: https://support.exclaimer.com/hc/en-gb/articles/360050643511-Onboarding-Connect-to-Microsoft-365
- type: Support
  url: https://support.exclaimer.com/hc/en-gb
- type: GitHubOrganization
  url: https://github.com/exclaimerltd
- type: ChangeLog
  url: changelog/exclaimer-changelog.yml
- type: Deprecation
  url: https://exclaimer.com/support/discontinued/
- type: LLMsTxt
  url: llms/exclaimer-llms.txt
- type: Plans
  url: plans/exclaimer-plans-pricing.yml
x-enrichment:
  date: '2026-08-13'
  status: enriched
  artifacts_added: 22
  pass: local-v1
  note: Round 1 (2026-07-19) recorded "Exclaimer does not publish a public developer API reference". That was wrong. STEP
    0b contract discovery found the Exclaimer Cloud API reference at https://cloudapi.exclaimer.com/ — server-rendered, not
    a JS shell — with a real OpenAPI 3.0.1 served anonymously at https://cloudapi.exclaimer.com/openapi.json (HTTP 200, 39
    operations, 59 schemas). The docs are public; only the ExApiToken is gated to the distributor network.

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