CTlogs.io

CTlogs.io is a Certificate Transparency search service operated by Lyalpha GmbH (Düsseldorf, Germany; HRB 106435, Amtsgericht Düsseldorf). It indexes publicly-trusted TLS certificates from major CT logs and offers structured search by exact hostname or SHA-256 fingerprint (issuer, validity window, names on the certificate), a live check of the certificate a host serves right now, and CA certificate lookups. It provides a subscription REST API at https://api.ctlogs.io authenticated with an X-API-Key header, an MCP server at https://mcp.ctlogs.io/mcp, and free single-purpose web tools. It comes from the same team as DomainKits.

CTlogs.io publishes 6 API contracts indexed on the APIs.io network, including Certs API, Me API, Search API, and 3 more. Tagged areas include Company, Certificate Transparency, TLS Certificates, SSL, and Security.

The CTlogs.io catalog on APIs.io includes 1 JSON-LD context and 1 Spectral governance ruleset.

CTlogs.io’s developer surface includes authentication, documentation, pricing, engineering blog, FAQ, and 32 more developer resources.

🌐 Visit website 📡 Profile data on GitHub

52.7/100 developing Agent 52/100 agent native Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessPaid

1 published contract 1 MCP Servers 2 Agent Skills

CompanyCertificate TransparencyTLS Certificates SSL Security PKI Domains MCP

Kin Score

Kin Score How this is scored →
scored 2026-11-13 · rubric v0.28.0

Composite quality — 52.7/100 · developing

Contract Quality 12.7 / 21

Developer Ergonomics 7.2 / 17

Access Clarity 13.0 / 17

Operational Transparency 3.7 / 11

Contract Governance 2.2 / 10

Discoverability 5.5 / 9

Regulatory Posture 2.8 / 15

Agent readiness — 52/100 · agent native

Machine-Readable Contract 18 / 18

Agentic Access Contract 10 / 10

Documented Reversibility 6 / 6

MCP Server 12 / 12

Machine-Readable Auth 10 / 10

Idempotency 9 / 9

Stable Error Semantics 8 / 8

Request/Response Examples 0 / 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 4 / 4

Delegated User Identity 6 / 6

Protected Resource Metadata 5 / 5

Registration Without a Human 6 / 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 does not apply to this provider. The published contracts declare no write operations, and a read-only API cannot create-or-update. The facet is excluded from this provider's denominator entirely — not scored zero. A reference or data API is not deficient for being unable to upsert.

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):

A2A Agent Card +8 pts — a2a/-a2a.yml manifest, graded on conformance.grade against A2A 1.0.0 Ask about this →
Request/Response Examples +7 pts — share of operations carrying request/response examples; else an Examples / Code Samples link Ask about this →
Typed Event Surface +6 pts — AsyncAPI document, OR webhooks/callbacks objects in the as-published OpenAPI, OR common[].type includes Webhooks Ask about this →
Agentic Commerce Well-Known Document +5 pts — a parsing /.well-known/ucp.json or acp.json declaring a version and at least one service, OR (0.27) a live x402 payment challenge from _data/x402-adoption.json — `self` when its endpoints are on the provider's own domain, `platform` when they are on a vendor's Ask about this →
Well-Known Catalog +4 pts — common[].type includes WellKnown, APICatalog, or api-catalog Ask about this →
Consent & Bot Identity +3 pts — common[].type includes AIPREF, ContentSignal, WebBotAuth, or HTTPMessageSignatures Ask about this →

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

Developer Ergonomics scores 42.3 — up to +11.5 composite points Ask about this →
Contract Quality scores 59.8 — up to +10.1 composite points Ask about this →
Contract Governance scores 22.0 — up to +9.4 composite points Ask about this →

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.

Not sure how this applies to your stack? Ask about any one item. Kin Lane reads every question, looks at your profile and your situation, and replies with what a fix would take — scoped to that one area, priced up front, yours whether you ship it or not. Ask a question →

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/ctlogs-io/apis.yml: open an issue on github.com/api-evangelist/ctlogs-io 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 4

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)

OAuth 2.0 Protected Resource Metadata

measured — observed by APIs.io (verified)

Dynamic Client Registration

measured — observed by APIs.io (published)

OpenAPI

measured — observed by APIs.io (published)

APIs 6

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

CTlogs.io MCP Connector

Remote MCP connector exposing read-only Certificate Transparency lookup tools to AI assistants, as advertised on ctlogs.io.

CTlogs.io Certs API

The Certs API from CTlogs.io — 1 operation(s) for certs.

CTlogs.io Me API

The Me API from CTlogs.io — 1 operation(s) for me.

CTlogs.io Search API

The Search API from CTlogs.io — 1 operation(s) for search.

CTlogs.io Stats API

The Stats API from CTlogs.io — 1 operation(s) for stats.

CTlogs.io Subdomains API

The Subdomains API from CTlogs.io — 1 operation(s) for subdomains.

MCP Servers 1

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

CTlogs.io MCP Connector

Official remote MCP connector from CTlogs.io (Lyalpha GmbH) giving AI assistants read-only Certificate Transparency lookups over the same index as the CTlogs.io site and API. St...

MCP SERVER

Agent Skills 2

Packaged agent skills for driving this provider's APIs from an AI assistant.

ctlogs-io-certificate-lookup

AGENT SKILL

ctlogs-io-subdomain-discovery

AGENT SKILL

CTlogs.io API pricing

Prices published by CTlogs.io.

Plan	Price
Guest	10 searches a day as a visitor
Credit pack	$10 once
Basic	$29.99/ month
Standard	$69.99/ month

Plan details, limits and sources →

Rate limits

Certificate queries per hour (Basic): Certificate queries (hostname or fingerprint), per hour – 1,000 1,000
Certificate queries per hour (Standard): Certificate queries (hostname or fingerprint), per hour – 1,000 1,000
Request rate (Basic): Request rate, per second – 2 5

All 9 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

CTlogs.io Plans Pricing

4 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

CTlogs.io Rate Limits

9 limits

RATE LIMITS

Terms of Service 1

What its API terms permit and prohibit, quoted from its own page.

CTlogs.io

13 quoted statements, read from CTlogs.io's own page on 2026-11-09.

TERMS

Privacy & Data 1

Its role, the data it processes, retention and transfers, quoted from its own privacy page.

CTlogs.io

30 quoted statements, read from CTlogs.io's own page on 2026-11-09.

PRIVACY

Eligibility 1

Who may sign up and where, quoted from its own terms.

CTlogs.io

5 quoted statements, read from CTlogs.io's own page on 2026-11-09.

ELIGIBILITY

AI Preferences 1

Its stance on AI training, inference and agents, quoted from its own pages.

CTlogs.io

1 quoted statement, read from CTlogs.io's own page on 2026-11-09.

AI PREFS

Data License 1

How its data and outputs may be reused, quoted from its own terms.

CTlogs.io

2 quoted statements, read from CTlogs.io's own page on 2026-11-09.

LICENSE

Semantic Vocabularies 1

JSON-LD contexts and semantic vocabularies used across these APIs.

Ctlogs Io Context

3 classes · 12 properties

JSON-LD

Spectral Rules 1

Spectral governance rulesets for linting and validating these APIs. Counts are the severity each rule declares, not results of running them.

CTlogs.io API Rules

51 rules · 49 error-severity 1 warn-severity 1 info-severity

SPECTRAL

OpenAPI Overlays 1

Overlays applied on top of this provider's contracts. Each card says who wrote it: a document the provider publishes, or one API Evangelist derived or generated.

CTlogs.io Openapi Overlay

4 actions · update · ctlogs-io-openapi.yml

DERIVED

JSON Schema 2

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

Bucket

4 properties

JSON SCHEMA

Envelope

5 properties

JSON SCHEMA

Security Posture 2

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

CTlogs.io Authentication

apiKey · 2 schemes

SECURITY

CTlogs.io Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Agentic Access (API Evangelist recommendations) 1

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

CTlogs.io Agentic Access

5 operations

5 operations · 0 acting

AGENTIC

Resources

Get Started 2

Portal, sign-up, and the first successful call

DeveloperPortal

DeveloperPortal

Login

Documentation 2

Reference material describing how the API behaves

Documentation

Documentation

AIPreferences

AIPreferences

Agent Surfaces 5

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgentSkill

LLMsTxt

MCPServer

WellKnown

Design & Contract 8

Pagination, idempotency, versioning, errors, and events

Spectral

JSONLD

Vocabulary

DataModel

Conventions

Lifecycle

ErrorCatalog

Conformance

Scroll for all 8

Build 2

SDKs, sample code, and the tooling you integrate with

ToolCrosswalk

ToolCrosswalk

GitHubOrganization

GitHubOrganization

Access & Security 2

Authentication, authorization, and security posture

Authentication

Authentication

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

RateLimits

RateLimits

FAQ

FAQ

Commercial 6

Pricing, plans, and the legal terms of use

Plans

Pricing

TermsOfService

PrivacyPolicy

UsageTerms

DataLicense

Company 2

The organization behind the API

Website

Website

Blog

Blog

Other 6

Properties that don't map to a standard resource type

Overlay

Hosts

Vendors

Imprint

DataProcessing

Eligibility

Source (apis.yml)

aid: ctlogs-io
name: CTlogs.io
description: CTlogs.io is a Certificate Transparency search service operated by Lyalpha GmbH (Düsseldorf, Germany; HRB 106435,
  Amtsgericht Düsseldorf). It indexes publicly-trusted TLS certificates from major CT logs and offers structured search by
  exact hostname or SHA-256 fingerprint (issuer, validity window, names on the certificate), a live check of the certificate
  a host serves right now, and CA certificate lookups. It provides a subscription REST API at https://api.ctlogs.io authenticated
  with an X-API-Key header, an MCP server at https://mcp.ctlogs.io/mcp, and free single-purpose web tools. It comes from the
  same team as DomainKits.
url: https://artifacts.apis.io/ctlogs-io/apis.yml
x-type: company
x-source: harvest:mcp-registry
x-tier: profiled
x-tier-reason: enrichment pass 2026-11-04 (modular-v1; was harvest)
accessModel:
  pricing: paid
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Paid
  confidence: high
  probe_state: covered
  source:
  - plans
  - authentication
  - rate-limits
  - security
  generated: '2026-11-13'
  method: derived
specificationVersion: '0.20'
created: '2026-11-04'
modified: '2026-11-04'
tags:
- Company
- Certificate Transparency
- TLS Certificates
- SSL
- Security
- PKI
- Domains
- MCP
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
image: https://ctlogs.io/og.png?v=4
common:
- type: AgenticAccess
  url: agentic-access/ctlogs-io-agentic-access.yml
- type: RateLimits
  url: rate-limits/ctlogs-io-rate-limits.yml
- type: Plans
  url: plans/ctlogs-io-plans-pricing.yml
- type: Spectral
  url: rules/ctlogs-io-rules.yml
- type: JSONLD
  url: json-ld/ctlogs-io-context.jsonld
- type: Vocabulary
  url: vocabulary/ctlogs-io-vocabulary.yml
- type: AgentSkill
  url: skills/_index.yml
- type: DataModel
  url: data-model/ctlogs-io-data-model.yml
- type: Conventions
  url: conventions/ctlogs-io-conventions.yml
- type: Lifecycle
  url: lifecycle/ctlogs-io-lifecycle.yml
- type: ErrorCatalog
  url: errors/ctlogs-io-problem-types.yml
- type: Conformance
  url: conformance/ctlogs-io-conformance.yml
- type: Overlay
  url: overlays/ctlogs-io-openapi-overlay.yaml
- type: LLMsTxt
  url: llms/ctlogs-io-llms.txt
- type: ToolCrosswalk
  url: mcp/ctlogs-io-tool-crosswalk.yml
- type: MCPServer
  url: mcp/ctlogs-io-mcp.yml
- type: WellKnown
  url: well-known/ctlogs-io-well-known.yml
- type: Hosts
  url: hosts/ctlogs-io-hosts.yml
- type: Vendors
  url: vendors/ctlogs-io-vendors.yml
- type: DeveloperPortal
  url: https://api.ctlogs.io</div
- type: Authentication
  url: authentication/ctlogs-io-authentication.yml
- type: Website
  url: https://ctlogs.io/
- type: Documentation
  url: https://ctlogs.io/docs
- type: Pricing
  url: https://ctlogs.io/pricing
- type: Blog
  url: https://ctlogs.io/blog
- type: FAQ
  url: https://ctlogs.io/faq
- type: Login
  url: https://ctlogs.io/member/login
- type: TermsOfService
  url: https://ctlogs.io/terms
- type: PrivacyPolicy
  url: https://ctlogs.io/privacy
- type: Imprint
  url: https://ctlogs.io/imprint
- type: GitHubOrganization
  url: https://github.com/ABTdomain
- type: DomainSecurity
  url: security/ctlogs-io-domain-security.yml
- type: UsageTerms
  url: terms/ctlogs-io-terms-of-service.yml
- type: DataProcessing
  url: privacy/ctlogs-io-privacy-policy.yml
- type: Eligibility
  url: eligibility/ctlogs-io-eligibility.yml
- type: AIPreferences
  url: ai-preferences/ctlogs-io-ai-preferences.yml
- type: DataLicense
  url: data-license/ctlogs-io-data-license.yml
apis:
- aid: ctlogs-io:ctlogs-io-mcp
  name: CTlogs.io MCP Connector
  description: Remote MCP connector exposing read-only Certificate Transparency lookup tools to AI assistants, as advertised
    on ctlogs.io.
  humanURL: https://ctlogs.io/mcp
  baseURL: https://mcp.ctlogs.io/mcp
  tags:
  - MCP
  - Certificate Transparency
  properties:
  - type: Documentation
    url: https://ctlogs.io/mcp
- aid: ctlogs-io:ctlogs-io-certs-api
  name: CTlogs.io Certs API
  description: The Certs API from CTlogs.io — 1 operation(s) for certs.
  humanURL: https://ctlogs.io/docs
  baseURL: https://api.ctlogs.io
  tags:
  - Certs
  properties:
  - type: OpenAPI
    url: openapi/ctlogs-io-certs-api-openapi.yml
  - type: Documentation
    url: https://ctlogs.io/docs
  - type: APIReference
    url: https://ctlogs.io/docs
  - type: JSONSchema
    url: json-schema/ctlogs-io-envelope-schema.json
- aid: ctlogs-io:ctlogs-io-me-api
  name: CTlogs.io Me API
  description: The Me API from CTlogs.io — 1 operation(s) for me.
  humanURL: https://ctlogs.io/docs
  baseURL: https://api.ctlogs.io
  tags:
  - Me
  properties:
  - type: OpenAPI
    url: openapi/ctlogs-io-me-api-openapi.yml
  - type: Documentation
    url: https://ctlogs.io/docs
  - type: APIReference
    url: https://ctlogs.io/docs
  - type: JSONSchema
    url: json-schema/ctlogs-io-bucket-schema.json
- aid: ctlogs-io:ctlogs-io-search-api
  name: CTlogs.io Search API
  description: The Search API from CTlogs.io — 1 operation(s) for search.
  humanURL: https://ctlogs.io/docs
  baseURL: https://api.ctlogs.io
  tags:
  - Search
  properties:
  - type: OpenAPI
    url: openapi/ctlogs-io-search-api-openapi.yml
  - type: Documentation
    url: https://ctlogs.io/docs
  - type: APIReference
    url: https://ctlogs.io/docs
  - type: JSONSchema
    url: json-schema/ctlogs-io-envelope-schema.json
- aid: ctlogs-io:ctlogs-io-stats-api
  name: CTlogs.io Stats API
  description: The Stats API from CTlogs.io — 1 operation(s) for stats.
  humanURL: https://ctlogs.io/docs
  baseURL: https://api.ctlogs.io
  tags:
  - Stats
  properties:
  - type: OpenAPI
    url: openapi/ctlogs-io-stats-api-openapi.yml
  - type: Documentation
    url: https://ctlogs.io/docs
  - type: APIReference
    url: https://ctlogs.io/docs
  - type: JSONSchema
    url: json-schema/ctlogs-io-envelope-schema.json
- aid: ctlogs-io:ctlogs-io-subdomains-api
  name: CTlogs.io Subdomains API
  description: The Subdomains API from CTlogs.io — 1 operation(s) for subdomains.
  humanURL: https://ctlogs.io/docs
  baseURL: https://api.ctlogs.io
  tags:
  - Subdomains
  properties:
  - type: OpenAPI
    url: openapi/ctlogs-io-subdomains-api-openapi.yml
  - type: Documentation
    url: https://ctlogs.io/docs
  - type: APIReference
    url: https://ctlogs.io/docs
  - type: JSONSchema
    url: json-schema/ctlogs-io-envelope-schema.json
x-coverage:
  state: covered
  reason: identity-verified
  detail: Name and legal entity read from the ctlogs.io title and imprint (Lyalpha GmbH). GitHub org ABTdomain is linked from
    the ctlogs.io homepage ("Open Source Tools & Data") and names DomainKits, which llms.txt says is from the same team.
  evidence:
  - url: https://ctlogs.io/
    status: 200
  - url: https://ctlogs.io/imprint
    status: 200
  - url: https://ctlogs.io/docs
    status: 200
  - url: https://ctlogs.io/pricing
    status: 200
  - url: https://ctlogs.io/blog
    status: 200
  - url: https://ctlogs.io/faq
    status: 200
  - url: https://ctlogs.io/member/login
    status: 200
  - url: https://ctlogs.io/terms
    status: 200
  - url: https://ctlogs.io/privacy
    status: 200
  - url: https://github.com/ABTdomain
    status: 200
  - url: https://ctlogs.io/og.png?v=4
    status: 200
  - url: https://ctlogs.io/llms.txt
    status: 200
x-enrichment:
  date: '2026-11-04'
  status: enriched
  artifacts_added: 37
  pass: modular-v1
  engine: identity=anthropic,contract=anthropic,surfaces=anthropic,docs=anthropic,regulatory=anthropic

CTlogs.io API — frequently asked questions

Does CTlogs.io have an API?

Yes. APIs.io lists 6 APIs from CTlogs.io, including CTlogs.io MCP Connector, CTlogs.io Certs API and CTlogs.io Me API, and 3 more.

Is there an OpenAPI specification for the CTlogs.io API?

Yes. APIs.io indexes 5 OpenAPI specifications for CTlogs.io, each linked for download from this page.

How do I authenticate with the CTlogs.io API?

CTlogs.io documents its authentication (apiKey · 2 schemes). The details are profiled on APIs.io as CTlogs.io Authentication.

How much does the CTlogs.io API cost?

CTlogs.io publishes its prices; its Guest plan is 10 searches a day as a visitor as of 2026-11-04. APIs.io lists 4 pricing plans for CTlogs.io, with each plan's price, limits and inclusions under Pricing on this page.

Does CTlogs.io have an MCP server?

Yes. APIs.io lists 1 MCP server for CTlogs.io: Official remote MCP connector from CTlogs.io (Lyalpha GmbH) giving AI assistants read-only Certificate Transparency lookups over the same index as the CTlogs.io site and API. Streamable HTTP transport

Is the CTlogs.io API ready for AI agents?

CTlogs.io has a Kin Score of 52.7 out of 100 (developing) and an Agent Readiness score of 52.0 (agent-native), scored by API Evangelist on 2026-11-13.

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