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How to OpenAPI to TypeScript Converter Online

1. 1

   Paste your OpenAPI 3.0, OpenAPI 3.1, or Swagger 2.0 specification in JSON or YAML format into the editor.

2. 2

   Choose your target output format: TypeScript Interfaces (for declaration merging and class implementation), Type Aliases (for complex unions and primitives), or Zod Runtime Schemas (for dynamic validation and static inference).

3. 3

   Set code generation options such as custom type prefixing (e.g., "Api" or "Dto"), readonly properties, and explicit export keywords.

4. 4

   Enable "Preserve Descriptions" to convert OpenAPI schema and parameter descriptions into native JSDoc docstrings for rich IDE autocomplete.

5. 5

   Enable "Generate Path Types" to create strongly-typed parameter interfaces, request body types, and HTTP status code response types for all REST operations.

6. 6

   Click "Convert" or press ⌘↵ (Mac) / Ctrl+Enter (Windows) to instantly execute AST dereferencing and code emission.

7. 7

   Copy the generated TypeScript or Zod code directly to your clipboard or download the output as types.ts or schema.ts.

OpenAPI to TypeScript Converter Features

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  Full Multi-Specification Compatibility: Seamlessly parses and dereferences OpenAPI 3.0.x, OpenAPI 3.1.x, and legacy Swagger 2.0 definitions.

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  Universal JSON & YAML Parser: Automatically detects syntax and parses both YAML (.yaml/.yml) and JSON (.json) API contracts without manual toggles.

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  Three Specialized Emission Targets: Output standard TypeScript interfaces, union-capable type aliases, or Zod validation schemas with z.infer<T>.

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  Complete $ref JSON Pointer Dereferencing: Resolves nested, cross-document, and circular component schemas across components/schemas and definitions.

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  Polymorphic Schema Composition: Reliably converts allOf into intersection types (&) or interface inheritance, and oneOf/anyOf into discriminated union types (|).

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  End-to-End REST Path Typing: Emits typed URL parameters, query parameters, header parameters, request bodies, and status-specific response models (e.g. 200, 201, 400, 404).

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  Rich JSDoc Annotation Preservation: Transforms summary, description, and deprecated annotations into full IDE hover tooltips and documentation comments.

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  Enum & Literal Mapping: Converts string, numeric, and mixed OpenAPI enum arrays into type-safe string literal unions or typed constants.

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  Custom Type Namespace & Prefixing: Add prefixes (e.g., ApiUser, DtoOrder) across all emitted types to prevent naming collisions with domain models.

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  Immutability & Readonly Modifiers: Optionally marks all object properties with TypeScript readonly modifiers for functional and reactive state stores.

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  Automated Zod Constraint Emission: Maps string formats (email, uuid, uri, datetime) and numeric constraints (minimum, maximum) into actionable Zod validators.

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  Zero-Telemetry In-Memory Processing: Specs are parsed and compiled entirely in-memory with zero disk persistence, server caching, or external API transmission.

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  Developer Ergonomics: Native keyboard shortcuts (⌘↵ to convert, ⌘⇧C to copy, ⌘⇧K to clear) and one-click example loading.

Supported Formats & Dialects

The OpenAPI to TypeScript Converter supports 6 syntax formats and dialects for accurate parsing and processing.

OpenAPI 3.1 (Modern Standard)

Full JSON Schema Draft 2020-12 alignment, type arrays including null, dynamic Webhooks definitions, prefixItems tuple typing, and patternProperties.

OpenAPI 3.0 (Widespread Standard)

Components object with schemas, securitySchemes, requestBodies, parameters, and nullable property modifiers for REST services.

Swagger 2.0 (Legacy Specification)

Definitions object, basePath and host routing, query/header/formData parameters, and Swagger security definitions.

TypeScript Interfaces (OOP & Declaration Merging)

Generates standard TypeScript interface declarations with extends clauses, readonly modifiers, and full declaration merging compatibility.

TypeScript Type Aliases & Discriminated Unions

Generates flexible type aliases for union types, intersection types, primitive aliases, and polymorphic discriminated unions.

Zod Runtime Validation Schemas

Generates runtime validation schemas using Zod with string format helpers (email, url, uuid, datetime), numeric bounds, and infer<T> typings.

Frequently Asked Questions

How are internal and nested $ref JSON pointers resolved during TypeScript generation?

The converter utilizes a multi-pass AST parser to dereference all internal JSON pointers (such as "#/components/schemas/Pet" in OpenAPI 3.x or "#/definitions/User" in Swagger 2.0) prior to emitting TypeScript code. Referenced objects are converted into named, reusable TypeScript interfaces or type aliases, preserving model modularity while inlining anonymous sub-schemas where appropriate.

What is the architectural difference between Interfaces, Type Aliases, and Zod output modes?

Interfaces mode outputs standard TypeScript "interface" declarations, which support declaration merging and class implements clauses—ideal for traditional service layers. Type Aliases mode emits "type" declarations, which natively support unions, intersections, and mapped types. Zod mode outputs runtime schema objects (e.g., const UserSchema = z.object({...})) paired with inferred static types (type User = z.infer<typeof UserSchema>), providing both build-time type safety and runtime JSON boundary validation.

How does the converter handle schema composition keywords (allOf, oneOf, and anyOf)?

Schemas using "allOf" are evaluated as composition structures and emitted as TypeScript intersection types (A & B) or interface extensions (interface Child extends Parent). Schemas utilizing "oneOf" or "anyOf" are compiled into TypeScript union types (A | B), faithfully representing polymorphic data models and discriminated unions when a discriminator property is declared.

What types are generated when "Generate Path Types" is toggled?

When path typing is enabled, the converter parses the "paths" object and emits dedicated types for every HTTP operation: URL path parameters and query parameters (e.g., GetUserByIdParams), request payload types (e.g., UpdateUserRequestBody), and response types mapped by HTTP status codes (e.g., GetUserResponse200, GetUserResponse404, GetUserDefaultResponse).

How are optional properties and nullable fields distinguished between OpenAPI 3.0 and 3.1?

Properties excluded from the "required" array are marked with the TypeScript optional token ("?:"). For value nullability, OpenAPI 3.0 "nullable: true" annotations and OpenAPI 3.1 multi-type arrays (such as type: ["string", "null"]) are converted to explicit union types with null (e.g., string | null), preventing undefined-versus-null confusion at runtime.

How are string and numeric OpenAPI enums converted into TypeScript?

OpenAPI enum definitions are converted into strict TypeScript string or numeric literal unions (e.g., type Status = "active" | "inactive" | "suspended"). When targeting Zod mode, enums are emitted using z.enum([...]) for strings or z.union([...]) for mixed types, ensuring valid runtime payload enforcement.

Can the generated TypeScript types be used with Fetch, Axios, TanStack Query, and openapi-fetch?

Yes. The output is pure, idiomatic TypeScript code with standard exports. You can import generated types directly into generic fetch wrappers, Axios response generics (axios.get<GetUserResponse200>), TanStack Query hooks (useQuery<Pet[]>), or integrate them into lightweight type-safe clients like openapi-fetch and tRPC.

Does the generator support circular schema references without crashing?

Yes. Because TypeScript natively supports recursive type aliases and interface property references (e.g., an interface Category containing children?: Category[]), the dereferencing engine detects cyclic pointers and preserves the named type reference rather than creating infinite dereference loops.

How does custom type prefixing and readonly property generation work?

Supplying a custom prefix (such as "Api" or "Dto") prepends that PascalCase prefix across all generated model names and path types (e.g., ApiPet, ApiPetSchema). Enabling the readonly modifier adds "readonly " to all interface and type properties, enforcing immutable state management in Redux, Zustand, or React state hooks.

Is my proprietary API specification stored, cached, or sent to third parties?

No. Specification parsing, AST dereferencing, and TypeScript emission execute entirely within an isolated in-memory execution context. No specification contents, endpoint routes, parameters, or schema structures are ever written to disk, logged, cached, or transmitted to any third-party service.

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