liboas — library for OpenAPI Specification
OpenAPI 3.2 library for C23

liboas is a C23 library for parsing, validating, and serving OpenAPI 3.2 specifications. Two-layer architecture: OAS Model (parse and represent OpenAPI documents) and Compiled Runtime (pre-compiled validator and router for high-performance request/response validation).

Designed for integration with iohttp via adapter pattern, but usable standalone.

git clone https://github.com/dantte-lp/liboas.git && cd liboas
cmake --preset clang-debug
cmake --build --preset clang-debug
ctest --preset clang-debug

graph TB
    subgraph "OAS Model Layer"
        PARSE["JSON/YAML Parser"]
        MODEL["OAS Document Model"]
        REF["$ref Resolver"]
        SCHEMA["JSON Schema 2020-12"]
    end

    subgraph "Compiled Runtime Layer"
        COMPILE["Schema Compiler"]
        VALID["Request/Response Validator"]
        MATCH["Path Matcher"]
        EMIT["Spec Emitter (JSON/YAML)"]
    end

    subgraph "Integration"
        ADAPTER["iohttp Adapter"]
        SCALAR["Scalar UI"]
    end

    PARSE --> MODEL
    MODEL --> REF --> MODEL
    MODEL --> SCHEMA
    MODEL --> COMPILE
    COMPILE --> VALID
    COMPILE --> MATCH
    MODEL --> EMIT
    ADAPTER --> VALID
    ADAPTER --> MATCH
    ADAPTER --> EMIT

    style COMPILE fill:#6BA539,color:#fff
    style VALID fill:#6BA539,color:#fff

• Full OpenAPI 3.2 document model (paths, operations, schemas, components)
• JSON Schema 2020-12 validation (type, format, pattern, min/max, allOf/oneOf/anyOf)
• Pre-compiled schema validators for zero-allocation hot path
• $ref resolution (local, remote, recursive with cycle detection)
• Path template matching with parameter extraction
• Request/response validation middleware
• JSON and YAML spec emission
• iohttp adapter for automatic route validation
• Scalar UI integration for API documentation

Full documentation is available in docs/:

See docs/en/08-development.md for development workflow, coding standards, and testing requirements.

GPLv3 - see LICENSE for details.