swaggercppModern C++23 toolkit for Swagger / OpenAPI.

Parse, validate, traverse, write and serve OpenAPI documents — with a typed document model and zero surprises.

📄

Typed document model

Document, Info, PathItem, Operation, Parameter, Response, Schema — every OpenAPI node as a real C++ struct, not stringly-typed maps.

🔄

JSON and YAML, both ways

Read, write and round-trip between formats with a single API. YAML detection is automatic; JSON output is configurable.

✅

Validation with actionable issues

Each Issue carries a severity, a JSON Pointer-style path, and a message. No exceptions for expected failures.

🧭

Visitor-based traversal

Implement DocumentVisitor once and walk every path, operation, parameter, response and schema deterministically.

🌐

Embedded Swagger UI

Spin up a local HTTP server with Swagger UI and /openapi.json in one call. Optional browser auto-launch.

📦

First-class packaging

Installable via vcpkg (upstream), Conan recipe, CMake package config, FetchContent, or custom registry.

Why swaggercpp?

Most C++ OpenAPI libraries stop at "parse to a JSON tree". swaggercpp goes further: it exposes OpenAPI nodes as regular C++23 structures, so tooling authors can inspect and manipulate specifications with normal field access and standard containers.

cpp

#include "swaggercpp/swaggercpp.hpp"

auto result = swaggercpp::DocumentReader::read_file("openapi.yaml");
if (!result) return 1;

swaggercpp::DocumentValidator validator;
const auto report = validator.validate(result.value());

for (const auto& op : result.value().paths) {
    for (const auto& [method, operation] : op.second.operations) {
        std::println("{} {} → {}", swaggercpp::to_string(method), op.first,
                     operation.operation_id.value_or("(anonymous)"));
    }
}

What's in the box

DocumentReader — format-detecting parser for JSON and YAML
DocumentWriter — serialiser with pretty-printing and round-trip helpers
DocumentValidator — semantic checks independent of syntax
DocumentWalker — deterministic visitor traversal
SwaggerUiServer — embedded HTTP server with Swagger UI shell
Result<T> — non-throwing return type with issues attached

License

Released under the MIT License.