Cataas

Cataas (Cat as a Service) is a free, open-source REST API that returns random cat images and GIFs with optional tags, filters, sizing, and text overlays. The service is widely embedded in tutorials, demos, README files, and chat applications as a friction-free image source. The canonical implementation lives at github.com/cataas/cataas and runs at cataas.com.

Cataas publishes 4 APIs on the APIs.io network, including Admin API, Catalog API, Cats API, and 1 more. Tagged areas include Animals, Cats, Image, Open-Source, and Public APIs.

The Cataas catalog on APIs.io includes 1 JSON-LD context and 2 Spectral governance rulesets.

Cataas’ developer surface includes authentication, tooling, and 13 more developer resources.

🌐 Visit website 📡 Source on GitHub

26.2/100 thin ▬ flat Agent 22/100 agent aware Full breakdown ↓
scored 2026-09-08 · rubric v0.20.0

4 APIs 9 Features 5 Use Cases

Animals Cats Image Open-Source Public APIs

Kin Score

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

Composite quality — 26.2/100 · thin

Contract Quality 6.6 / 23

Developer Ergonomics 6.9 / 18

Access Clarity 0.0 / 18

Operational Transparency 0.3 / 12

Contract Governance 3.1 / 11

Discoverability 7.3 / 9

Create-or-Update Ergonomics 0.0 / 10

Agent readiness — 22/100 · 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 0 / 8

Request/Response Examples 7 / 7

Rate-Limit Signaling 0 / 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

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/cataas: 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 4

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

Cataas Admin API

Administrative operations on the cat catalog (admin token required)

Cataas Catalog API

Browse cats, tags, and stats programmatically (JSON)

Cataas Cats API

Random and tagged cat image retrieval

Cataas Upload API

Submit a cat image (rate-limited / moderated)

Open Collections 5

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

API Collection

OPEN COLLECTION

Cataas Admin API

OPEN COLLECTION

Cataas Admin Catalog API

OPEN COLLECTION

Cataas Admin Cats API

OPEN COLLECTION

Cataas Admin Upload API

OPEN COLLECTION

Features 9

Notable capabilities this provider offers.

Random Cat Image

GET /cat returns a random cat image (JPEG, PNG, or GIF).

Tagged Cat Retrieval

GET /cat/{tag} returns a random cat matching one or more comma-separated tags.

Animated GIFs

GET /cat/gif returns a random animated cat.

Text Overlay

GET /cat/says/{text} renders user-supplied text on top of a random cat with configurable font size, color, and background.

Image Filters

filter=blur|mono|negate|custom with per-channel and per-property tuning (brightness, hue, saturation, RGB).

Sizing and Cropping

type, width, height, fit, and position query parameters resize and crop the returned image.

JSON Catalog API

/api/cats, /api/tags, /api/count expose the catalog programmatically.

Content Negotiation

json=true returns a metadata document instead of binary; html=true returns an embedding wrapper page.

Free and Unauthenticated

All read endpoints are public and require no API key.

Scroll for all 9

Semantic Vocabularies 1

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

Cataas Context

4 classes · 11 properties

JSON-LD

Spectral Rules 2

Spectral governance rulesets for linting and validating these APIs.

Cataas API Rules

5 rules · 4 warnings 1 info

SPECTRAL

Cataas API Rules

40 rules · 12 errors 24 warnings 4 info

SPECTRAL

JSON Schema 4

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

Cat

9 properties

JSON SCHEMA

CountResponse

1 properties

JSON SCHEMA

EditCatRequest

1 properties

JSON SCHEMA

UploadCatRequest

2 properties

JSON SCHEMA

JSON Structure 4

JSON Structure definitions describing this provider's data shapes.

Cat Structure

9 properties

JSON STRUCTURE

Count Response Structure

1 properties

JSON STRUCTURE

Edit Cat Request Structure

1 properties

JSON STRUCTURE

Upload Cat Request Structure

2 properties

JSON STRUCTURE

Examples 4

Example request and response payloads for these APIs.

Cat Example

9 fields

EXAMPLE

Count Response Example

1 fields

EXAMPLE

Edit Cat Request Example

1 fields

EXAMPLE

Upload Cat Request Example

2 fields

EXAMPLE

Security Posture 2

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

Cataas Authentication

http · 1 scheme

SECURITY

Cataas Domain Security

TLSv1.3 · DMARC

SECURITY

Agentic Access 1

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

Cataas Agentic Access

15 operations · 4 acting

AGENTIC

Use Cases 5

What developers build with this provider.

Tutorials and Demos

Embed live cat images in API tutorials, learn-to-code lessons, and conference demos.

README Decoration

Decorate open-source READMEs and personal sites with rotating cat imagery.

Chat Bots and Slash Commands

Slack, Discord, and Teams bots fetch random cats on demand via /cat or /cat/says.

Mocking Image-Heavy APIs

Stand in for a real image-CDN-backed API while prototyping front-end layouts.

Image Pipeline Testing

Exercise resize, format-conversion, and filtering pipelines with predictable image input.

Integrations 4

Pre-built integrations with other platforms and tools.

Slack

Official slack-command repo wires /cat into Slack workspaces.

Discord

Official discord-bot repo provides a Cataas Discord integration.

Pipeworx MCP Gateway

Community MCP server (pipeworx-io/mcp-cataas) wraps the API for use by Claude and other MCP clients.

Public APIs Catalog

Listed in the public-apis/public-apis Animals category.

Solutions 1

Packaged solutions this provider offers.

Self-Hosted Catalog

Run your own Cataas instance from cataas/cataas (Node.js + MongoDB + sharp) to power internal demos or branded image services.

Resources

Agent Surfaces 1

MCP servers, agent skills, and machine-readable catalogs

AgenticAccess

AgenticAccess

Design & Contract 3

Pagination, idempotency, versioning, errors, and events

SpectralRules

SpectralRules

Vocabulary

Vocabulary

JSONLD

JSONLD

Build 6

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Canonical Cataas server (Node.js)

GitHubRepository

Cataas Discord bot

GitHubRepository

Cataas Slack slash command

GitHubRepository

Cataas image editor library

GitHubRepository

MCP Server (community via Pipeworx Gateway)

Tools

Access & Security 2

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Authentication

Authentication

Operate 1

Status, limits, changes, and where to get help

IssueTracker

IssueTracker

Company 1

The organization behind the API

Website

Website

Other 1

Properties that don't map to a standard resource type

PublicAPIsListing

PublicAPIsListing

Source (apis.yml)

aid: cataas
deliveryModel:
  model: unknown
  open_source: unknown
  commercial: false
  callable_host: true
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - openapi
  - repository-unlicensed
  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
  generated: '2026-09-03'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/cataas.png
name: Cataas
description: Cataas (Cat as a Service) is a free, open-source REST API that returns random cat images and GIFs with optional
  tags, filters, sizing, and text overlays. The service is widely embedded in tutorials, demos, README files, and chat applications
  as a friction-free image source. The canonical implementation lives at github.com/cataas/cataas and runs at cataas.com.
url: https://cataas.com/
specificationVersion: '0.23'
created: '2026-05-28'
modified: '2026-05-30'
x-source: public-apis/public-apis
x-category: Animals
x-type: opensource
x-tier: 3
x-tier-reason: bulk-registered-from-public-apis
tags:
- Animals
- Cats
- Image
- Open-Source
- Public APIs
tags_raw:
- Animals
- Cats
- Images
- Open Source
- Public APIs
apis:
- aid: cataas:cataas-admin-api
  name: Cataas Admin API
  description: Administrative operations on the cat catalog (admin token required)
  humanURL: https://cataas.com/
  baseURL: https://cataas.com
  tags:
  - Admin
  properties:
  - type: OpenAPI
    url: openapi/cataas-admin-api-openapi.yml
  - type: Documentation
    url: https://cataas.com/
  - type: JSONSchema
    url: json-schema/cat-schema.json
  - type: JSONSchema
    url: json-schema/count-response-schema.json
  - type: JSONSchema
    url: json-schema/upload-cat-request-schema.json
  - type: JSONSchema
    url: json-schema/edit-cat-request-schema.json
  - type: JSONStructure
    url: json-structure/cat-structure.json
  - type: JSONStructure
    url: json-structure/count-response-structure.json
  - type: JSONStructure
    url: json-structure/upload-cat-request-structure.json
  - type: JSONStructure
    url: json-structure/edit-cat-request-structure.json
  - type: Examples
    url: examples/cat-example.json
  - type: Examples
    url: examples/count-response-example.json
  - type: Examples
    url: examples/upload-cat-request-example.json
  - type: Examples
    url: examples/edit-cat-request-example.json
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-js
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-go
  - type: SDKs
    url: https://github.com/chimpook/cataas-api-php
- aid: cataas:cataas-catalog-api
  name: Cataas Catalog API
  description: Browse cats, tags, and stats programmatically (JSON)
  humanURL: https://cataas.com/
  baseURL: https://cataas.com
  tags:
  - Catalog
  properties:
  - type: OpenAPI
    url: openapi/cataas-catalog-api-openapi.yml
  - type: Documentation
    url: https://cataas.com/
  - type: JSONSchema
    url: json-schema/cat-schema.json
  - type: JSONSchema
    url: json-schema/count-response-schema.json
  - type: JSONSchema
    url: json-schema/upload-cat-request-schema.json
  - type: JSONSchema
    url: json-schema/edit-cat-request-schema.json
  - type: JSONStructure
    url: json-structure/cat-structure.json
  - type: JSONStructure
    url: json-structure/count-response-structure.json
  - type: JSONStructure
    url: json-structure/upload-cat-request-structure.json
  - type: JSONStructure
    url: json-structure/edit-cat-request-structure.json
  - type: Examples
    url: examples/cat-example.json
  - type: Examples
    url: examples/count-response-example.json
  - type: Examples
    url: examples/upload-cat-request-example.json
  - type: Examples
    url: examples/edit-cat-request-example.json
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-js
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-go
  - type: SDKs
    url: https://github.com/chimpook/cataas-api-php
- aid: cataas:cataas-cats-api
  name: Cataas Cats API
  description: Random and tagged cat image retrieval
  humanURL: https://cataas.com/
  baseURL: https://cataas.com
  tags:
  - Cats
  properties:
  - type: OpenAPI
    url: openapi/cataas-cats-api-openapi.yml
  - type: Documentation
    url: https://cataas.com/
  - type: JSONSchema
    url: json-schema/cat-schema.json
  - type: JSONSchema
    url: json-schema/count-response-schema.json
  - type: JSONSchema
    url: json-schema/upload-cat-request-schema.json
  - type: JSONSchema
    url: json-schema/edit-cat-request-schema.json
  - type: JSONStructure
    url: json-structure/cat-structure.json
  - type: JSONStructure
    url: json-structure/count-response-structure.json
  - type: JSONStructure
    url: json-structure/upload-cat-request-structure.json
  - type: JSONStructure
    url: json-structure/edit-cat-request-structure.json
  - type: Examples
    url: examples/cat-example.json
  - type: Examples
    url: examples/count-response-example.json
  - type: Examples
    url: examples/upload-cat-request-example.json
  - type: Examples
    url: examples/edit-cat-request-example.json
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-js
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-go
  - type: SDKs
    url: https://github.com/chimpook/cataas-api-php
- aid: cataas:cataas-upload-api
  name: Cataas Upload API
  description: Submit a cat image (rate-limited / moderated)
  humanURL: https://cataas.com/
  baseURL: https://cataas.com
  tags:
  - Upload
  properties:
  - type: OpenAPI
    url: openapi/cataas-upload-api-openapi.yml
  - type: Documentation
    url: https://cataas.com/
  - type: JSONSchema
    url: json-schema/cat-schema.json
  - type: JSONSchema
    url: json-schema/count-response-schema.json
  - type: JSONSchema
    url: json-schema/upload-cat-request-schema.json
  - type: JSONSchema
    url: json-schema/edit-cat-request-schema.json
  - type: JSONStructure
    url: json-structure/cat-structure.json
  - type: JSONStructure
    url: json-structure/count-response-structure.json
  - type: JSONStructure
    url: json-structure/upload-cat-request-structure.json
  - type: JSONStructure
    url: json-structure/edit-cat-request-structure.json
  - type: Examples
    url: examples/cat-example.json
  - type: Examples
    url: examples/count-response-example.json
  - type: Examples
    url: examples/upload-cat-request-example.json
  - type: Examples
    url: examples/edit-cat-request-example.json
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-js
  - type: SDKs
    url: https://github.com/iArmanKarimi/Cataas-API-go
  - type: SDKs
    url: https://github.com/chimpook/cataas-api-php
common:
- type: IssueTracker
  url: https://github.com/cataas/cataas/issues
- type: AgenticAccess
  url: agentic-access/cataas-agentic-access.yml
- type: DomainSecurity
  url: security/cataas-domain-security.yml
- type: Authentication
  url: authentication/cataas-authentication.yml
- type: Website
  url: https://cataas.com/
- type: GitHubOrganization
  url: https://github.com/cataas
- type: GitHubRepository
  url: https://github.com/cataas/cataas
  title: Canonical Cataas server (Node.js)
- type: GitHubRepository
  url: https://github.com/cataas/discord-bot
  title: Cataas Discord bot
- type: GitHubRepository
  url: https://github.com/cataas/slack-command
  title: Cataas Slack slash command
- type: GitHubRepository
  url: https://github.com/cataas/image-editor
  title: Cataas image editor library
- type: Tools
  title: MCP Server (community via Pipeworx Gateway)
  url: https://github.com/pipeworx-io/mcp-cataas
- type: PublicAPIsListing
  url: https://github.com/public-apis/public-apis
- type: SpectralRules
  url: rules/cataas-spectral-rules.yml
- type: Vocabulary
  url: vocabulary/cataas-vocabulary.yaml
- type: JSONLD
  url: json-ld/cataas-context.jsonld
- type: Features
  data:
  - name: Random Cat Image
    description: GET /cat returns a random cat image (JPEG, PNG, or GIF).
  - name: Tagged Cat Retrieval
    description: GET /cat/{tag} returns a random cat matching one or more comma-separated tags.
  - name: Animated GIFs
    description: GET /cat/gif returns a random animated cat.
  - name: Text Overlay
    description: GET /cat/says/{text} renders user-supplied text on top of a random cat with configurable font size, color,
      and background.
  - name: Image Filters
    description: filter=blur|mono|negate|custom with per-channel and per-property tuning (brightness, hue, saturation, RGB).
  - name: Sizing and Cropping
    description: type, width, height, fit, and position query parameters resize and crop the returned image.
  - name: JSON Catalog API
    description: /api/cats, /api/tags, /api/count expose the catalog programmatically.
  - name: Content Negotiation
    description: json=true returns a metadata document instead of binary; html=true returns an embedding wrapper page.
  - name: Free and Unauthenticated
    description: All read endpoints are public and require no API key.
- type: UseCases
  data:
  - name: Tutorials and Demos
    description: Embed live cat images in API tutorials, learn-to-code lessons, and conference demos.
  - name: README Decoration
    description: Decorate open-source READMEs and personal sites with rotating cat imagery.
  - name: Chat Bots and Slash Commands
    description: Slack, Discord, and Teams bots fetch random cats on demand via /cat or /cat/says.
  - name: Mocking Image-Heavy APIs
    description: Stand in for a real image-CDN-backed API while prototyping front-end layouts.
  - name: Image Pipeline Testing
    description: Exercise resize, format-conversion, and filtering pipelines with predictable image input.
- type: Integrations
  data:
  - name: Slack
    description: Official slack-command repo wires /cat into Slack workspaces.
  - name: Discord
    description: Official discord-bot repo provides a Cataas Discord integration.
  - name: Pipeworx MCP Gateway
    description: Community MCP server (pipeworx-io/mcp-cataas) wraps the API for use by Claude and other MCP clients.
  - name: Public APIs Catalog
    description: Listed in the public-apis/public-apis Animals category.
- type: Solutions
  data:
  - name: Self-Hosted Catalog
    description: Run your own Cataas instance from cataas/cataas (Node.js + MongoDB + sharp) to power internal demos or branded
      image services.
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

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