ogen

No reflection

JSON encoding is code-generated and optimized, using go-faster/jx for speed and to overcome encoding/json limitations
Validation is code-generated directly from the specification
No interface or any on the hot path

No boilerplate

Structures are generated from the OpenAPI v3 specification
Path arguments, headers and query parameters are parsed into typed structures
String formats like uuid, date, date-time and uri map to Go types directly

Type-safe client & server

Statically typed client and server generated from a single spec
Implement one Handler interface and you are done
Code-generated static radix router for fast request dispatch

Optional & nullable

Optional and nullable fields without pointers when possible
Generated OptT, NilT and OptNilT wrappers with helpers
Array nil semantics follow the specification

Sum types

Sum types are generated for oneOf
Discriminator field is used when defined in the schema
Otherwise the variant is inferred by type, unique fields or enum values

Batteries included

OpenTelemetry tracing and metrics out of the box
Server-Sent Events (SSE) client generation
Middlewares, convenient errors and per-request options

From spec to Go, instantly

Describe your API once in OpenAPI v3 and let ogen generate a statically typed client and server.

petstore.yml
paths:
  /pet/{petId}:
    get:
      operationId: getPetById
      parameters:
        - name: petId
          in: path
          required: true
          schema:
            type: integer
            format: int64
      responses:
        '200':
          description: Pet
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Pet'

generated Go
// Pet describes #/components/schemas/Pet.
type Pet struct {
    ID   int64     `json:"id"`
    Name string    `json:"name"`
    Tag  OptUUID   `json:"tag"`
}

// Handler handles operations described
// by OpenAPI v3 specification.
type Handler interface {
    // GET /pet/{petId}
    GetPetById(ctx context.Context,
        params GetPetByIdParams) (*Pet, error)
}