# API Specifications

**Canonical:** https://apis.io/providers/specifications/  
**APIs profiled:** 13

Meta-index of the specification languages used to describe APIs, events, schemas, and service interfaces across the modern API landscape. This repo is the META layer above the topical repos that profile each individual specification — it catalogs every major HTTP, event-driven, schema, and service interface specification along with its current version, governing body, license, and tooling ecosystem.

## Kin Score — 15.7 / 100 (emerging)

Scored 2026-08-21 under rubric 0.12.0. Trend: flat (+0.0 from 15.7).

| Facet | Score |
|---|---|
| Discoverability | 74.1 |
| Contract Quality | 19.7 |
| Governance | 25.0 |
| Contract Governance | 25.0 |
| Operational Transparency | 2.6 |
| Developer Ergonomics | 0.0 |
| Commercial Clarity | 0.0 |
| Access Clarity | 0.0 |

## Agent readiness — 0.0 (human-only)

| Dimension | Value |
|---|---|
| Spec Presence | no |
| Agentic Access | no |
| Reversibility Documented | no |
| MCP Server | no |
| Auth Clarity | no |
| Idempotency | no |
| Error Semantics | no |
| OpenAPI Examples | no |
| Rate Limit Signal | no |
| Event Surface Described | no |
| Agent Skills | no |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |

## Access

Unknown — onboarding: unknown, pricing: unknown, trial: no (confidence: low).

## APIs (13)

- **OpenAPI Specification (OAS)** — The OpenAPI Specification (formerly Swagger) is the dominant industry standard for describing HTTP-based RESTful APIs. OAS describes endpoints, operations, parameters, request/r...
- **AsyncAPI Specification** — AsyncAPI is the open standard for describing event-driven and message-driven APIs across protocols such as Kafka, AMQP, MQTT, WebSocket, NATS, and SNS/SQS. AsyncAPI 3.0 (Decembe...
- **JSON Schema** — JSON Schema is a declarative language for annotating and validating JSON documents. It is the foundational schema language for most modern API specifications (OpenAPI 3.1, Async...
- **JSON Structure** — JSON Structure is an emerging open specification that extends and complements JSON Schema with a clearer, more code-generation-friendly type system designed for data contracts a...
- **GraphQL SDL** — GraphQL is a query language and runtime for APIs, defined by the GraphQL Specification. The GraphQL Schema Definition Language (SDL) is the declarative format used to define typ...
- **gRPC and Protocol Buffers** — gRPC is a high-performance RPC framework using HTTP/2 and Protocol Buffers (Protobuf) as its IDL and wire format. Service definitions are written in .proto files. gRPC is a CNCF...
- **Smithy** — Smithy is an open-source IDL and code-generation framework for defining services and SDKs, created and maintained by AWS. It is protocol-agnostic (HTTP REST, AWS JSON, MQTT, RPC...
- **TypeSpec** — TypeSpec (formerly Cadl) is a language for describing API shapes developed by Microsoft. TypeSpec definitions emit OpenAPI 3.x, JSON Schema, Protobuf, and other artifacts, and s...
- **RAML (RESTful API Modeling Language)** — RAML is a YAML-based modelling language for RESTful APIs, originally created by Mulesoft. RAML 1.0 (2016) is the current stable specification. RAML governance has effectively co...
- **API Blueprint** — API Blueprint is a Markdown-based specification language for describing web APIs, originally created by Apiary (acquired by Oracle). The spec is MIT licensed but development eff...
- **WSDL / SOAP** — The Web Services Description Language (WSDL) is the historical XML-based interface definition language for SOAP web services. WSDL 1.1 (2001) is the most widely deployed version...
- **JSON-RPC 2.0** — JSON-RPC 2.0 is a stateless, light-weight remote procedure call (RPC) protocol encoded in JSON. It is widely used in blockchain/Web3 APIs (Ethereum, Bitcoin), IDE language serve...
- **Tinybird API Spec** — The Tinybird API specification is a vendor-defined, declarative format for describing analytics endpoints (pipes), data sources, and parameters backed by ClickHouse. It is docum...

## Security (1)

- **Specifications Domain Security** — TLSv1.3 · HSTS · DMARC

## Use cases (5)

- **Specification Discovery and Cataloging** — Maintaining an enterprise inventory of specifications used across internal and partner APIs, mapped to their governing bodies and tooling.
- **Multi-Format Code Generation** — Choosing or layering specifications (TypeSpec or Smithy as a high-level model emitting OpenAPI, JSON Schema, and Protobuf) to generate SDKs across protocols.
- **Event-Driven Architecture Contracts** — Using AsyncAPI alongside Avro/Protobuf to define event schemas, channels, and operations for streaming and message-driven systems.
- **Governance and Linting Across Specs** — Applying Spectral or other linting frameworks against OpenAPI, AsyncAPI, and JSON Schema artifacts as part of an API governance program.
- **Legacy SOAP/WSDL Modernization** — Migrating legacy WSDL/SOAP interfaces to OpenAPI-described REST or gRPC service contracts as part of modernization initiatives.

## Tags

API Specification, Specification Languages, API Design, Contracts, Schemas, Interface Definitions, Standards

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/specifications/). Scores are computed from the provider's own public artifacts under a published rubric.