Tessian

Tessian, now part of Proofpoint, is an AI-powered email security platform that protects against inbound threats (phishing and impersonation), accidental data loss, and deliberate data exfiltration across its Defender, Guardian, Enforcer, Architect, and Constructor modules. The Tessian API is a RESTful, JSON, read-oriented interface that exports security-event, anomaly, company-risk, user-monitoring, audit-log, and trigger data into SIEMs and other data-management tools. It authenticates with a static API token, paginates by checkpoint, and returns ISO 8601 UTC timestamps.

Tessian publishes 2 APIs on the APIs.io network: Beta Endpoints API and Endpoints API. Tagged areas include Company, Enterprise, Email Security, Cybersecurity, and Data Loss Prevention.

Tessian’s developer surface includes documentation, API reference, authentication, support, and 15 more developer resources.

🌐 Visit website 📡 Source on GitHub

31.7/100 thin ▬ flat Agent 26/100 agent aware saas Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

1 APIs

Company Enterprise Email Security Cybersecurity Data Loss Prevention SIEM Security Phishing

Kin Score

Kin Score How this is scored →
scored 2026-09-08 · rubric v0.20.0

Composite quality — 31.7/100 · thin

Contract Quality 11.7 / 23

Developer Ergonomics 8.0 / 18

Access Clarity 1.9 / 18

Operational Transparency 0.3 / 12

Contract Governance 0.5 / 11

Discoverability 6.8 / 9

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 26/100 · agent aware

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 0 / 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 0 / 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

Create-or-Update Ergonomics applies to this provider. This API accepts writes, so it carries 10 points of the composite. It is scored from the published contracts themselves: whether a caller can create-or-update in one call, whether the write accepts a key the caller already holds, and whether the response says which branch ran. Without that, every write needs a search-and-branch in front of it, and the first time that check is skipped a duplicate record is created. Scored against the observed mean rather than raw — a provider at the catalog average is unchanged by this facet, not penalised by it.

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/tessian: 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 2

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

Tessian Beta Endpoints API

The Beta Endpoints API from Tessian — 1 operation(s) for beta endpoints.

Tessian Endpoints API

The Endpoints API from Tessian — 9 operation(s) for endpoints.

Open Collections 11

Open, tool-agnostic API collections (OpenAPI-derived and Bruno).

API Collection

OPEN COLLECTION

Tessian Anomalies API

OPEN COLLECTION

Tessian Anomalies Audits API

OPEN COLLECTION

Tessian Anomalies Beta Endpoints API

OPEN COLLECTION

Tessian Anomalies Deprecated API

OPEN COLLECTION

Tessian Anomalies Endpoints API

OPEN COLLECTION

Tessian Anomalies Events API

OPEN COLLECTION

Tessian Anomalies Groups API

OPEN COLLECTION

Tessian Anomalies Monitoring API

OPEN COLLECTION

Tessian Anomalies Risk API

OPEN COLLECTION

Tessian Anomalies Triggers API

OPEN COLLECTION

Scroll for all 11

Security Posture 2

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

Tessian Authentication

apiKey · 1 scheme

SECURITY

Tessian Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access 1

Recommended x-agentic-access execution contracts for AI agents.

Tessian Agentic Access

13 operations · 5 acting

AGENTIC

Resources

Get Started 1

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

APIReference

APIReference

Agent Surfaces 4

MCP servers, agent skills, and machine-readable catalogs

X-MCPServerCandidate

LLMsTxt

AgentSkill

AgenticAccess

Design & Contract 5

Pagination, idempotency, versioning, errors, and events

Conventions

ErrorCatalog

Conformance

DataModel

Lifecycle

Build 1

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

Support

Support

Commercial 1

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

Company 1

The organization behind the API

Website

Website

Other 1

Properties that don't map to a standard resource type

Overlay

Overlay

Source (apis.yml)

aid: tessian
deliveryModel:
  model: saas
  open_source: false
  commercial: true
  callable_host: false
  label: Hosted service · you call their endpoint
  confidence: medium
  source:
  - openapi
  - pricing
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: unknown
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Unknown
  confidence: low
  source:
  - authentication
  - security
  - url: https://www.tessian.com
    status: 301
    note: declared website redirects to https://www.proofpoint.com/us/tessian-is-now-proofpoint — a different registrable
      domain (tessian.com -> proofpoint.com), possible rename or acquisition (probed 2026-09-03, roadmap#169)
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/tessian.png
name: Tessian
description: Tessian, now part of Proofpoint, is an AI-powered email security platform that protects against inbound threats
  (phishing and impersonation), accidental data loss, and deliberate data exfiltration across its Defender, Guardian, Enforcer,
  Architect, and Constructor modules. The Tessian API is a RESTful, JSON, read-oriented interface that exports security-event,
  anomaly, company-risk, user-monitoring, audit-log, and trigger data into SIEMs and other data-management tools. It authenticates
  with a static API token, paginates by checkpoint, and returns ISO 8601 UTC timestamps.
url: https://raw.githubusercontent.com/api-evangelist/tessian/refs/heads/main/apis.yml
x-type: company
x-source: vc-portfolio
x-backed-by:
- accel
- balderton-capital
x-tier: stub
x-tier-reason: portfolio-lead
specificationVersion: '0.23'
created: '2026-07-17'
modified: '2026-07-21'
tags:
- Company
- Enterprise
- Email Security
- Cybersecurity
- Data Loss Prevention
- SIEM
- Security
- Phishing
apis:
- aid: tessian:tessian-beta-endpoints-api
  name: Tessian Beta Endpoints API
  description: The Beta Endpoints API from Tessian — 1 operation(s) for beta endpoints.
  humanURL: https://developer.tessian.com/documentation/api/index.html
  baseURL: https://your-domain.tessian-platform.com
  tags:
  - Beta Endpoints
  properties:
  - type: OpenAPI
    url: openapi/tessian-beta-endpoints-api-openapi.yml
  - type: Documentation
    url: https://developer.tessian.com/documentation/api/index.html
  - type: APIReference
    url: https://developer.tessian.com/documentation/api/index.html
- aid: tessian:tessian-endpoints-api
  name: Tessian Endpoints API
  description: The Endpoints API from Tessian — 9 operation(s) for endpoints.
  humanURL: https://developer.tessian.com/documentation/api/index.html
  baseURL: https://your-domain.tessian-platform.com
  tags: []
  tags_raw:
  - Endpoints
  properties:
  - type: OpenAPI
    url: openapi/tessian-endpoints-api-openapi.yml
  - type: Documentation
    url: https://developer.tessian.com/documentation/api/index.html
  - type: APIReference
    url: https://developer.tessian.com/documentation/api/index.html
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: DeveloperPortal
  url: https://developer.tessian.com/
- type: Documentation
  url: https://developer.tessian.com/documentation/api/index.html
- type: APIReference
  url: https://developer.tessian.com/documentation/api/index.html
- type: Authentication
  url: authentication/tessian-authentication.yml
- type: Conventions
  url: conventions/tessian-conventions.yml
- type: ErrorCatalog
  url: errors/tessian-problem-types.yml
- type: Conformance
  url: conformance/tessian-conformance.yml
- type: DataModel
  url: data-model/tessian-data-model.yml
- type: Lifecycle
  url: lifecycle/tessian-lifecycle.yml
- type: X-MCPServerCandidate
  url: mcp/tessian-mcp.yml
  note: 'Renamed from MCPServer 2026-09-03 (roadmap#247): the manifest self-describes as status: candidate — a tool list derived
    from the published API contracts, not an existing server. The scorer already read the manifest and reported mcp_server
    correctly; the MCPServer type was crediting the artifact-type surfaces with a server that does not exist.'
- type: LLMsTxt
  url: llms/tessian-llms.txt
- type: Overlay
  url: overlays/tessian-openapi-overlay.yaml
- type: AgentSkill
  url: skills/_index.yml
- type: AgenticAccess
  url: agentic-access/tessian-agentic-access.yml
- type: DomainSecurity
  url: security/tessian-domain-security.yml
- type: GitHubOrganization
  url: https://github.com/tessian
- type: TermsOfService
  url: https://www.proofpoint.com/us/legal/api-terms-of-use
- type: Support
  url: mailto:support@tessian.com
- type: Website
  url: https://www.tessian.com
x-enrichment:
  date: '2026-07-21'
  status: enriched
  artifacts_added: 14
  pass: local-v1

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