RESTful

Representational State Transfer (REST) is an architectural style for designing networked applications using stateless HTTP communication and uniform interfaces. RESTful describes systems and APIs that conform to the REST constraints: client-server separation, statelessness, cacheability, layered system, uniform interface, and (optionally) code-on-demand. This index covers the RESTful design paradigm including maturity models, API design patterns, documentation formats, and key reference implementations.

RESTful is listed with 5 APIs on the APIs.io network. Tagged areas include Architecture, HTTP, and Web Services.

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

📡 Profile data on GitHub

11.8/100 emerging ▬ flat Agent 1/100 human only Front door AI 1/6 silent Heartbeat 99/100 alive Full breakdown ↓
scored 2026-11-13 · rubric v0.28.0 · Show this score on your site →

AccessFreemium

5 APIs

Architecture HTTP Web Services

Kin Score

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

Composite quality — 11.8/100 · emerging

Contract Quality 2.3 / 21

Developer Ergonomics 1.6 / 17

Access Clarity 1.1 / 17

Operational Transparency 0.8 / 11

Contract Governance 1.0 / 10

Discoverability 4.6 / 9

Regulatory Posture 0.7 / 15

Agent readiness — 1/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

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 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

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 could not be measured. We hold no machine-readable contract for this provider to read, so there is nothing to measure a write surface against. Excluded rather than scored zero: never-measured and measured-empty are different facts. Publishing an OpenAPI is what makes this facet — and several others — scorable at all.

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):

Machine-Readable Contract +18 pts — api_specs includes an OpenAPI document Ask about this →
MCP Server +12 pts — deployment.mode + probe verdict on the mcp/ manifest, not the pointer; an unprobed slug falls back to authorship Ask about this →
Agentic Access Contract +10 pts — agentic_access artifact present (x-agentic-access), graded by author Ask about this →
Machine-Readable Auth +10 pts — a served openid-configuration/oauth-authorization-server carrying `issuer` (served), else the securitySchemes class in the provider OpenAPIs — bound (mutualTLS, DPoP, Signature) > negotiable (oauth2 authorizationCode/clientCredentials, openIdConnect) > bearer (http bearer, apiKey) Ask about this →
Idempotency +9 pts — OpenAPI mutating operations declare an idempotency key — a header, a request-body property, or a named de-duplication token whose own description says so (verified); else common[].type matches /idempoten/i (documented) Ask about this →
Stable Error Semantics +8 pts — OpenAPI $refs a shared error schema across 4xx/5xx responses (verified), else common[].type includes ErrorCatalog / ErrorCodes / DeclineCodes Ask about this →

12 more unmet checks in the Agent Readiness table above.

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

Contract Quality scores 10.7 — up to +22.3 composite points Ask about this →
Access Clarity scores 6.4 — up to +18.7 composite points Ask about this →
Developer Ergonomics scores 9.5 — up to +18.1 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.

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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/restful/apis.yml: open an issue on github.com/api-evangelist/restful 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 1

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.

HTTP

tagged — the provider's own APIs.json carries the standard as a tag; implementation not verified

APIs 5

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

Richardson Maturity Model

A model by Leonard Richardson that breaks down the maturity of a RESTful API into four levels: Level 0 (The Swamp of POX), Level 1 (Resources), Level 2 (HTTP Verbs), and Level 3...

JSON:API

A specification for building APIs in JSON that standardizes resource representation, relationships, error handling, and metadata. Reduces over-fetching and under-fetching with s...

HAL - Hypertext Application Language

A simple format for including hypermedia links in JSON or XML API responses. HAL uses _links for links and _embedded for embedded resources, providing a consistent way to make R...

OpenAPI Specification

The OpenAPI Specification (OAS) defines a standard, language-agnostic interface for HTTP APIs. OpenAPI 3.x is the most widely-used format for describing RESTful APIs, enabling d...

RFC 9110 - HTTP Semantics

The IETF standard defining HTTP semantics: methods, status codes, header fields, content negotiation, authentication, and request/response message formats. The authoritative ref...

RESTful API pricing

Not yet checked against RESTful's own pricing page. Compiled by API Evangelist on 2026-05-04; confirm before you rely on a figure. A free plan or tier is listed.

Plan	Price
Free freemium	Free
Professional paid	Free
Enterprise enterprise	—

Plan details, limits and sources →

Rate limits

Free Tier Default: 10 requests per minute
Free Tier Monthly Quota: 1000 requests per month
Professional Tier Default: 100 requests per minute

Compiled by API Evangelist, not yet checked against RESTful's documentation. All 5 limits →

Pricing Plans 1

Published pricing tiers and plan structures.

RESTful Plans Pricing

3 plans

PLANS

Rate Limits 1

Documented rate limits and quota policies.

RESTful Rate Limits

5 limits

RATE LIMITS

FinOps 1

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

RESTful Finops

FINOPS

Semantic Vocabularies 1

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

Restful Context

13 classes · 7 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.

RESTful — jsonschema rules

5 rules · 3 warn-severity 2 info-severity

SPECTRAL

JSON Schema 1

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

RESTful API Description

10 properties

JSON SCHEMA

JSON Structure 1

JSON Structure definitions describing this provider's data shapes.

RESTful Api Description Structure

0 properties

JSON STRUCTURE

Security Posture 1

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

RESTful Domain Security

TLSv1.3 · HSTS · DMARC

SECURITY

Resources

Build 1

SDKs, sample code, and the tooling you integrate with

IANA HTTP Status Codes

IANA HTTP Status Codes

Access & Security 1

Authentication, authorization, and security posture

DomainSecurity

DomainSecurity

Operate 1

Status, limits, changes, and where to get help

RateLimits

RateLimits

Commercial 2

Pricing, plans, and the legal terms of use

Plans

Plans

FinOps

FinOps

Other 3

Properties that don't map to a standard resource type

Roy Fielding REST Dissertation

Roy Fielding REST Dissertation

IANA Link Relations

IANA Link Relations

RFC 6570 URI Templates

RFC 6570 URI Templates

Source (apis.yml)

aid: restful
deliveryModel:
  model: unknown
  open_source: false
  commercial: false
  callable_host: false
  label: Delivery model not determined — needs a product licence on record
  confidence: low
  source:
  - none
  generated: '2026-08-28'
  method: derived
accessModel:
  pricing: freemium
  onboarding: unknown
  trial: false
  try_now: false
  public: false
  label: Freemium
  confidence: low
  source:
  - plans
  - security
  generated: '2026-11-13'
  method: derived
image: https://kinlane-images.s3.amazonaws.com/shared/apis-json/icons/restful.png
name: RESTful
description: 'Representational State Transfer (REST) is an architectural style for designing networked applications using
  stateless HTTP communication and uniform interfaces. RESTful describes systems and APIs that conform to the REST constraints:
  client-server separation, statelessness, cacheability, layered system, uniform interface, and (optionally) code-on-demand.
  This index covers the RESTful design paradigm including maturity models, API design patterns, documentation formats, and
  key reference implementations.'
type: Index
url: https://raw.githubusercontent.com/api-evangelist/restful/refs/heads/main/apis.yml
tags:
- Architecture
- HTTP
- Web Services
created: '2025-01-01'
modified: '2026-05-02'
specificationVersion: '0.23'
apis:
- aid: restful:richardson-maturity-model
  name: Richardson Maturity Model
  description: 'A model by Leonard Richardson that breaks down the maturity of a RESTful API into four levels: Level 0 (The
    Swamp of POX), Level 1 (Resources), Level 2 (HTTP Verbs), and Level 3 (Hypermedia Controls / HATEOAS). Most modern APIs
    target Level 2.'
  humanURL: https://martinfowler.com/articles/richardsonMaturityModel.html
  tags:
  - Best Practices
  - Design Patterns
  - Maturity Model
  properties:
  - type: Documentation
    url: https://martinfowler.com/articles/richardsonMaturityModel.html
- aid: restful:json-api
  name: JSON:API
  description: A specification for building APIs in JSON that standardizes resource representation, relationships, error handling,
    and metadata. Reduces over-fetching and under-fetching with sparse fieldsets and compound documents.
  humanURL: https://jsonapi.org/
  tags:
  - Hypermedia
  - JSON
  - Standards
  properties:
  - type: Documentation
    url: https://jsonapi.org/format/
  - type: Website
    url: https://jsonapi.org/
- aid: restful:hal-specification
  name: HAL - Hypertext Application Language
  description: A simple format for including hypermedia links in JSON or XML API responses. HAL uses _links for links and
    _embedded for embedded resources, providing a consistent way to make REST APIs navigable.
  humanURL: https://stateless.co/hal_specification.html
  tags:
  - Hypermedia
  - JSON
  - Standards
  properties:
  - type: Documentation
    url: https://stateless.co/hal_specification.html
  - type: IETF Draft
    url: https://datatracker.ietf.org/doc/html/draft-kelly-json-hal
- aid: restful:openapi-specification
  name: OpenAPI Specification
  description: The OpenAPI Specification (OAS) defines a standard, language-agnostic interface for HTTP APIs. OpenAPI 3.x
    is the most widely-used format for describing RESTful APIs, enabling documentation, code generation, and validation.
  humanURL: https://spec.openapis.org/oas/latest.html
  tags:
  - Documentation
  - Standards
  - Tooling
  properties:
  - type: Specification
    url: https://spec.openapis.org/oas/latest.html
  - type: Website
    url: https://www.openapis.org/
- aid: restful:http-rfc-9110
  name: RFC 9110 - HTTP Semantics
  description: 'The IETF standard defining HTTP semantics: methods, status codes, header fields, content negotiation, authentication,
    and request/response message formats. The authoritative reference for RESTful HTTP API design.'
  humanURL: https://datatracker.ietf.org/doc/html/rfc9110
  tags:
  - HTTP
  - RFC
  - Standards
  properties:
  - type: Standards
    url: https://datatracker.ietf.org/doc/html/rfc9110
common:
- type: Plans
  url: plans/restful-plans-pricing.yml
- type: RateLimits
  url: rate-limits/restful-rate-limits.yml
- type: FinOps
  url: finops/restful-finops.yml
- type: DomainSecurity
  url: security/restful-domain-security.yml
- type: Roy Fielding REST Dissertation
  url: https://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm
- type: IANA HTTP Status Codes
  url: https://www.iana.org/assignments/http-status-codes/
- type: IANA Link Relations
  url: https://www.iana.org/assignments/link-relations/
- type: RFC 6570 URI Templates
  url: https://datatracker.ietf.org/doc/html/rfc6570
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com

RESTful API — frequently asked questions

Does RESTful have an API?

Yes. APIs.io lists 5 APIs from RESTful, including Richardson Maturity Model, JSON:API and HAL - Hypertext Application Language, and 2 more.

How much does the RESTful API cost?

APIs.io lists 3 pricing plans for RESTful, with each plan's price, limits and inclusions under Pricing on this page.

Is the RESTful API ready for AI agents?

RESTful has a Kin Score of 11.8 out of 100 (emerging) and an Agent Readiness score of 0.6 (human-only), scored by API Evangelist on 2026-11-13.

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