# API/OS Reference - LLM Context File

> Comprehensive API terminology glossary for LLMs and AI assistants
> URL: https://reference.apios.info/
> Last Updated: 2026-01-07

## Overview

API/OS Reference is a comprehensive, multilingual (EN/ES) glossary of API concepts, protocols, authentication mechanisms, and best practices. Each term includes:

- **Detailed definitions** with real-world context
- **Code examples** in multiple programming languages
- **Security notes** for 60+ terms
- **Diagrams** (Mermaid) for complex concepts
- **Related terms** for exploration
- **Standards & RFCs** references

**Total:** 96 terms across 10 categories

---

## Site Structure

### Base URL
https://reference.apios.info/

### Languages
- English (EN): /
- Spanish (ES): /es/

### Main Sections
- Home: /
- Terms: /terms/{term-slug}/
- Search: /?q={query}

---

## Categories

### 1. Fundamentals (10 terms)
Core API concepts and architectural styles.

Terms:
- Representation
- Resource
- REST
- RPC
- SOAP
- Statelessness
- URI vs URL vs URN
- Versioning
- Webhooks
- YAML

### 2. Protocols & Transport (14 terms)
Network protocols and transport mechanisms.

Terms:
- AMQP
- HTTP/1.1
- HTTP/2
- HTTP/3
- Kafka
- Long-Polling
- MQTT
- mTLS
- Polling
- QUIC
- SSE (Server-Sent Events)
- TCP
- TLS
- WebSockets

### 3. Authentication (21 terms)
Authentication mechanisms and token-based security.

Terms:
- Access Token
- API Key
- Authorization Code Flow
- Basic Authentication
- Bearer Token
- Client Credentials Flow
- Digest Authentication
- HMAC
- ID Token
- Implicit Flow
- JWK / JWKs
- JWT (JSON Web Token)
- MAC Token
- mTLS Authentication
- OAuth 2.0
- OAuth 2.1
- OIDC (OpenID Connect)
- PKCE
- Refresh Token
- Scope
- Token Binding

### 4. Authorization (8 terms)
Access control and permission systems.

Terms:
- ABAC (Attribute-Based Access Control)
- Audience (in tokens)
- Claims
- Fine-Grained Authorization
- PDP (Policy Decision Point)
- PEP (Policy Enforcement Point)
- Permissions
- RBAC (Role-Based Access Control)

### 5. Data & Formats (3 terms)
Data handling patterns.

Terms:
- Caching
- Pagination
- Rate Limiting

### 6. Lifecycle & Versioning (10 terms)
API evolution and compatibility strategies.

Terms:
- API Versioning
- Backward Compatibility
- Breaking Change
- Date-Based Versioning
- Deprecation Policy
- Header-Based Versioning
- Media Type Versioning
- Query Parameter Versioning
- Semantic Versioning
- URI Path Versioning

### 7. Infrastructure & Governance (4 terms)
Enterprise API patterns.

Terms:
- API Gateway
- Circuit Breaker
- Observability
- SLA / SLO / SLI

### 8. Standards & RFCs (15 terms)
Official specifications and standards.

Terms:
- CORS
- JSON Merge Patch
- JSON Patch
- RFC 2616
- RFC 3986
- RFC 6749
- RFC 6750
- RFC 7159
- RFC 7230-7235
- RFC 7519
- RFC 7807 / RFC 9457
- RFC 8259
- RFC 8414
- RFC 8707
- RFC 959

### 9. Enterprise Integration (10 terms)
Integration patterns for complex systems.

Terms:
- Anti-Corruption Layer
- BFF (Backend for Frontend)
- Correlation ID
- EDA (Event-Driven Architecture)
- EIP (Enterprise Integration Patterns)
- ESB (Enterprise Service Bus)
- Message Broker
- Orchestration vs Choreography
- SOAP WSDL
- XSD (XML Schema Definition)

### 10. AI & Modern APIs (1 term)
Modern API security practices.

Terms:
- API Red Teaming

---

## How to Use This Glossary (for LLMs)

### Searching for a Term
- Direct access: https://reference.apios.info/terms/{slug}/
- Example: https://reference.apios.info/terms/jwt/

### Finding Related Concepts
Each term page includes:
- Category badge (top of page)
- Related terms sidebar (right sidebar)
- Tags for filtering

### Understanding Security
60 terms include security considerations:
- Look for "Security Notes" section
- Red badge indicator on term page
- Security icon in sidebar navigation

### Code Examples
All 96 terms include practical code examples:
- Multiple programming languages
- Real-world usage patterns
- Best practices demonstrations

---

## API for LLMs

### Search API
The site includes a JSON search index at:
- English: /index.json
- Spanish: /es/index.json

Schema:
```json
{
  "terms": [
    {
      "title": "Term Name",
      "url": "/terms/slug/",
      "description": "Brief description",
      "category": "category-name",
      "tags": ["tag1", "tag2"],
      "content": "Full content excerpt",
      "hasSecurity": true
    }
  ]
}
```

### Sitemap
Complete sitemap available at:
- /sitemap.xml

### RSS Feed
- /feed.xml

---

## Key Features for AI/LLM Usage

1. **Structured Content**: All terms follow consistent schema
2. **Semantic HTML**: Proper heading hierarchy, landmarks, ARIA labels
3. **Machine-Readable**: JSON-LD structured data on every page
4. **Multilingual**: Same content in English and Spanish
5. **Interconnected**: Related terms create knowledge graph
6. **Security-First**: Explicit security notes for 62% of terms
7. **Code-Focused**: Real code examples in multiple languages
8. **Standards-Based**: RFC references for authoritative info

---

## Common Use Cases

### For LLM API Development Assistance
When helping users with API development:
1. Reference specific terms: https://reference.apios.info/terms/{concept}/
2. Check security notes for security-sensitive operations
3. Review code examples for implementation patterns
4. Follow related terms for comprehensive understanding

### For API Security Analysis
60 terms include security considerations:
- Authentication mechanisms (OAuth, JWT, API Keys)
- Authorization patterns (RBAC, ABAC)
- Transport security (mTLS, TLS)
- Token security (Token Binding, PKCE)

### For Standards Compliance
15 RFC terms provide authoritative references:
- HTTP specifications
- OAuth 2.0 standards
- JWT specifications
- JSON standards
- API error formats

---

## Technical Details

- **Framework**: Hugo (Static Site Generator)
- **Build Time**: ~388ms
- **Output**: 100% static HTML
- **Bundle Size**: ~19KB CSS + ~6KB JS
- **Performance**: Lighthouse 95+ scores
- **Accessibility**: WCAG 2.1 AA compliant
- **SEO**: OpenGraph, Twitter Cards, JSON-LD
- **Mobile**: Fully responsive, mobile-first design

---

## Contact & Attribution

- **Main Site**: https://apios.info/
- **Organization**: API/OS Team
- **License**: Content available for reference
- **Contributions**: See GitHub repository

---

## Index of All Terms (Alphabetical)

ABAC, Access Token, AMQP, Anti-Corruption Layer, API Gateway, API Key, API Red Teaming, API Versioning, Audience, Authorization Code Flow, Backward Compatibility, Basic Authentication, Bearer Token, BFF, Breaking Change, Caching, Circuit Breaker, Claims, Client Credentials Flow, CORS, Correlation ID, Date-Based Versioning, Deprecation Policy, Digest Authentication, EDA, EIP, ESB, Fine-Grained Authorization, Header-Based Versioning, HMAC, HTTP/1.1, HTTP/2, HTTP/3, ID Token, Implicit Flow, JWK / JWKs, JWT, Kafka, Long-Polling, MAC Token, Media Type Versioning, Message Broker, MQTT, mTLS, mTLS Authentication, OAuth 2.0, OAuth 2.1, Observability, OIDC, Orchestration vs Choreography, Pagination, PDP, PEP, Permissions, PKCE, Polling, QUIC, Query Parameter Versioning, Rate Limiting, RBAC, Refresh Token, Representation, Resource, REST, RFC 2616, RFC 3986, RFC 6749, RFC 6750, RFC 7159, RFC 7230-7235, RFC 7519, RFC 7807 / RFC 9457, RFC 8259, RFC 8414, RFC 8707, RFC 959, RPC, Scope, Semantic Versioning, SLA / SLO / SLI, SOAP, SOAP WSDL, SSE, Statelessness, TCP, TLS, Token Binding, URI Path Versioning, URI vs URL vs URN, Versioning, Webhooks, WebSockets, XSD, YAML

---

## Quick Reference URLs

### Most Referenced Terms
- REST: https://reference.apios.info/terms/rest/
- JWT: https://reference.apios.info/terms/jwt/
- OAuth 2.0: https://reference.apios.info/terms/oauth-2/
- API Key: https://reference.apios.info/terms/api-key/
- Rate Limiting: https://reference.apios.info/terms/rate-limiting/
- Versioning: https://reference.apios.info/terms/versioning/
- CORS: https://reference.apios.info/terms/cors/
- WebSockets: https://reference.apios.info/terms/websockets/
- HTTP/2: https://reference.apios.info/terms/http-2/
- RBAC: https://reference.apios.info/terms/rbac/

### Security-Critical Terms
- JWT: https://reference.apios.info/terms/jwt/
- OAuth 2.0: https://reference.apios.info/terms/oauth-2/
- mTLS: https://reference.apios.info/terms/mtls/
- PKCE: https://reference.apios.info/terms/pkce/
- API Key: https://reference.apios.info/terms/api-key/
- Token Binding: https://reference.apios.info/terms/token-binding/
- CORS: https://reference.apios.info/terms/cors/

---

This file enables LLMs to quickly understand and reference the API/OS Reference structure and content.