Cloud Custodian website screenshot

Cloud Custodian

Cloud Custodian is an open-source rules engine for cloud security, compliance, and cost-optimization governance now stewarded by Stacklet. Operators express policies as YAML files that select a cloud resource type, apply filters, and execute actions; the engine then runs those policies against AWS, Azure, and GCP via provider-specific plugins. Custodian does not expose a developer REST API of its own - integration is via the c7n CLI, the policy YAML schema, c7n-org for multi-account fan-out, and c7n-mailer for SQS-driven notifications.

Cloud Custodian publishes 1 API on the APIs.io network: C7n-Mailer. Tagged areas include Cloud Security, Compliance, Cost Optimization, Multi-Cloud, and Policy as Code.

The Cloud Custodian catalog on APIs.io includes 1 event-driven AsyncAPI specification, 1 JSON-LD context, and 2 Spectral governance rulesets.

Cloud Custodian’s developer surface includes documentation, getting-started guide, changelog, and 8 more developer resources.

🌐 Visit website 📡 Source on GitHub
44.5/100 developing ▬ flat Agent 25/100 agent aware Full breakdown ↓
scored 2026-07-28 · rubric v0.6
AccessFreemium
6 APIs
Cloud SecurityComplianceCost OptimizationMulti-CloudPolicy as Code

Kin Score

Kin Score Kin Score How this is scored →
scored 2026-07-28 · rubric v0.6
Composite quality — 44.5/100 · developing
Contract Quality 16.1 / 25
Developer Ergonomics 4.8 / 20
Commercial Clarity 7.9 / 20
Operational Transparency 6.8 / 13
Governance 2.5 / 12
Discoverability 6.5 / 10
Agent readiness — 25/100 · agent aware
Machine-Readable Contract 18 / 18
Agentic Access Contract 0 / 10
MCP Server 0 / 12
Machine-Readable Auth 0 / 10
Idempotency 0 / 9
Stable Error Semantics 0 / 8
Request/Response Examples 0 / 7
Rate-Limit Signaling 7 / 7
Typed Event Surface 6 / 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
Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/cloud-custodian: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

APIs 6

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

Cloud Custodian

Cloud Custodian provides rules-engine capabilities for managing cloud resources with security, compliance, and cost optimization policies.

Cloud Custodian AWS Provider

The Cloud Custodian AWS provider enables policy-as-code management of Amazon Web Services resources including EC2, S3, IAM, RDS, Lambda, and hundreds of other AWS service resour...

Cloud Custodian Azure Provider

The Cloud Custodian Azure provider enables policy-as-code management of Microsoft Azure resources including virtual machines, storage accounts, network security groups, and othe...

Cloud Custodian GCP Provider

The Cloud Custodian GCP provider enables policy-as-code management of Google Cloud Platform resources including Compute Engine instances, GCS buckets, Cloud SQL instances, and o...

Cloud Custodian C7n-Org

c7n-org is a Cloud Custodian tool for running policies across multiple cloud accounts, projects, or subscriptions in parallel. It uses an accounts configuration file with assume...

Cloud Custodian C7n-Mailer

c7n-mailer is a Cloud Custodian notification tool that subscribes to an SQS queue populated by policy actions and sends notifications via SES email, Slack messages, or integrati...

Pricing Plans 1

Published pricing tiers and plan structures.

Cloud Custodian Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

Cloud Custodian Rate Limits

5 limits

RATE LIMITS

FinOps 1

Cost, billing, and metering signals for API financial operations.

Cloud Custodian Finops

FINOPS

Event Specifications 1

AsyncAPI definitions for this provider's event-driven and streaming APIs.

Cloud Custodian c7n-mailer Notification Events

The Cloud Custodian c7n-mailer AsyncAPI defines the event-driven notification interface used by the Cloud Custodian policy engine to deliver policy violation alerts. When a poli...

ASYNCAPI

Semantic Vocabularies 1

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

Cloud Custodian Context

0 classes · 8 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Cloud Custodian API Rules

3 rules · 1 errors 2 warnings

SPECTRAL

Cloud Custodian API Rules

6 rules · 5 warnings 1 info

SPECTRAL

JSON Schema 1

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

Cloud Custodian Policy File

2 properties

JSON SCHEMA

Security Posture 1

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

Cloud Custodian Domain Security

TLSv1.3

SECURITY

Resources

Get Started 1

Portal, sign-up, and the first successful call

GettingStarted
GettingStarted

Documentation 3

Reference material describing how the API behaves

Documentation
Documentation
 JSONSchema
JSONSchema
 AsyncAPI
AsyncAPI

Design & Contract 1

Pagination, idempotency, versioning, errors, and events

JSONLDContext
JSONLDContext

Build 2

SDKs, sample code, and the tooling you integrate with

GitHubOrganization
GitHubOrganization
 GitHubRepository
GitHubRepository

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity
DomainSecurity

Operate 2

Status, limits, changes, and where to get help

Community
Community
 ChangeLog
ChangeLog

Company 1

The organization behind the API

Website
Website

Source (apis.yml)

apis.yml Raw ↑ 
aid: cloud-custodian
url: https://raw.githubusercontent.com/api-evangelist/cloud-custodian/refs/heads/main/apis.yml
name: Cloud Custodian
tags:
- Cloud Security
- Compliance
- Cost Optimization
- Multi-Cloud
- Policy as Code
type: Index
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: medium
  source:
  - plans
  generated: '2026-07-22'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/cloud-custodian.png
access: Open Source
created: '2025-01-01'
modified: '2026-04-27'
position: Consumer
kind: opensource
description: Cloud Custodian is an open-source rules engine for cloud security, compliance, and cost-optimization governance
  now stewarded by Stacklet. Operators express policies as YAML files that select a cloud resource type, apply filters, and
  execute actions; the engine then runs those policies against AWS, Azure, and GCP via provider-specific plugins. Custodian
  does not expose a developer REST API of its own - integration is via the c7n CLI, the policy YAML schema, c7n-org for multi-account
  fan-out, and c7n-mailer for SQS-driven notifications.
apis:
- aid: cloud-custodian:cloud-custodian
  name: Cloud Custodian
  tags:
  - Cloud Security
  - Policy as Code
  humanURL: https://cloudcustodian.io/
  properties:
  - url: https://cloudcustodian.io/docs/
    type: Documentation
  - url: https://cloudcustodian.io/docs/quickstart/index.html
    type: GettingStarted
  - url: https://cloudcustodian.io/docs/overview/capabilities.html
    type: Reference
  - url: https://github.com/cloud-custodian/cloud-custodian
    type: GitHubRepository
  - type: JSONSchema
    url: json-schema/cloud-custodian-policy-schema.json
  description: Cloud Custodian provides rules-engine capabilities for managing cloud resources with security, compliance,
    and cost optimization policies.
- aid: cloud-custodian:cloud-custodian-aws
  name: Cloud Custodian AWS Provider
  description: The Cloud Custodian AWS provider enables policy-as-code management of Amazon Web Services resources including
    EC2, S3, IAM, RDS, Lambda, and hundreds of other AWS service resource types. Policies can be run in multiple execution
    modes including serverless Lambda functions, AWS Config rules, and scheduled CloudWatch Events.
  humanURL: https://cloudcustodian.io/docs/aws/gettingstarted.html
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  properties:
  - url: https://cloudcustodian.io/docs/aws/gettingstarted.html
    type: GettingStarted
  - url: https://cloudcustodian.io/docs/aws/resources/index.html
    type: Reference
  - url: https://cloudcustodian.io/docs/aws/examples/index.html
    type: Documentation
  tags:
  - AWS
  - Cloud Security
  - Compliance
  - Policy as Code
- aid: cloud-custodian:cloud-custodian-azure
  name: Cloud Custodian Azure Provider
  description: The Cloud Custodian Azure provider enables policy-as-code management of Microsoft Azure resources including
    virtual machines, storage accounts, network security groups, and other Azure services. Policies can enforce security requirements,
    tagging standards, and cost controls across Azure subscriptions.
  humanURL: https://cloudcustodian.io/docs/azure/gettingstarted.html
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  properties:
  - url: https://cloudcustodian.io/docs/azure/gettingstarted.html
    type: GettingStarted
  - url: https://cloudcustodian.io/docs/azure/policy/resources/index.html
    type: Reference
  tags:
  - Azure
  - Cloud Security
  - Compliance
  - Policy as Code
- aid: cloud-custodian:cloud-custodian-gcp
  name: Cloud Custodian GCP Provider
  description: The Cloud Custodian GCP provider enables policy-as-code management of Google Cloud Platform resources including
    Compute Engine instances, GCS buckets, Cloud SQL instances, and other GCP services. Policies can be used to enforce security,
    compliance, and cost governance standards across GCP projects.
  humanURL: https://cloudcustodian.io/docs/gcp/gettingstarted.html
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  properties:
  - url: https://cloudcustodian.io/docs/gcp/gettingstarted.html
    type: GettingStarted
  - url: https://cloudcustodian.io/docs/gcp/resources/index.html
    type: Reference
  tags:
  - Cloud Security
  - Compliance
  - GCP
  - Policy as Code
- aid: cloud-custodian:cloud-custodian-c7n-org
  name: Cloud Custodian C7n-Org
  description: c7n-org is a Cloud Custodian tool for running policies across multiple cloud accounts, projects, or subscriptions
    in parallel. It uses an accounts configuration file with assumed roles to orchestrate Custodian execution at scale across
    AWS Organizations, Azure subscriptions, or GCP projects.
  humanURL: https://cloudcustodian.io/docs/tools/c7n-org.html
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  properties:
  - url: https://cloudcustodian.io/docs/tools/c7n-org.html
    type: Documentation
  tags:
  - Cloud Security
  - Multi-Account
  - Orchestration
- aid: cloud-custodian:cloud-custodian-c7n-mailer
  name: Cloud Custodian C7n-Mailer
  description: c7n-mailer is a Cloud Custodian notification tool that subscribes to an SQS queue populated by policy actions
    and sends notifications via SES email, Slack messages, or integrations with DataDog and Splunk. It enables teams to alert
    resource owners when Custodian policies detect policy violations.
  humanURL: https://cloudcustodian.io/docs/tools/c7n-mailer.html
  image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/apis-json-logo.jpg
  properties:
  - url: https://cloudcustodian.io/docs/tools/c7n-mailer.html
    type: Documentation
  - type: AsyncAPI
    url: asyncapi/cloud-custodian-mailer-asyncapi.yml
  tags:
  - Alerting
  - Email
  - Notifications
  - Slack
common:
- type: DomainSecurity
  url: security/cloud-custodian-domain-security.yml
- type: Website
  url: https://cloudcustodian.io/
- type: Documentation
  url: https://cloudcustodian.io/docs/
- type: GitHubOrganization
  url: https://github.com/cloud-custodian/cloud-custodian
- type: GettingStarted
  url: https://cloudcustodian.io/docs/quickstart/index.html
- type: Community
  url: https://cloudcustodian.io/community/
- type: GitHubRepository
  url: https://github.com/cloud-custodian/cloud-custodian
- type: ChangeLog
  url: https://github.com/cloud-custodian/cloud-custodian/releases
- type: JSONLDContext
  url: json-ld/cloud-custodian-context.jsonld
- type: JSONSchema
  url: json-schema/cloud-custodian-policy-schema.json
- type: AsyncAPI
  url: asyncapi/cloud-custodian-mailer-asyncapi.yml
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
specificationVersion: '0.19'