quicktype

Overview

quicktype turns data samples and schema definitions into typed models and supporting code for applications. It suits developers working with API data who want generated types and validation without translating each structure by hand. Its browser, CLI, and MCP options make it flexible across workflows, though it does not scaffold whole projects.

Its value is in recognizing more than field names: quicktype can infer distinctions such as nullability, enums, dates, and unions, then generate code to read, write, and validate data. That makes it a practical fit for API clients and teams that want IDEs or AI agents to work with typed data. Its output is only as representative as the input it receives, so useful results depend on samples or schemas that capture the structures an application needs to handle.

Key features

Infers models from varied inputs

quicktype accepts sample JSON, API URLs, JSON Schema, TypeScript, and GraphQL queries. It can infer optional fields, numeric types, dates, UUIDs, enums, unions, maps, nested type names, and equivalent structures. This breadth helps when real data has meaningful variations, but teams should ensure their examples cover those variations before relying on generated models.

Generates serialization and validation code

Generated output can include types alongside code for reading, writing, and validating data in the target language. Support spans more than 25 languages, including C, C#, C++, Go, Java, Kotlin, Python, Rust, Swift, and TypeScript. That makes quicktype useful across varied stacks; the feature set is focused on schema-to-code generation rather than project scaffolding.

Works in browser, CLI, and MCP clients

The browser app generates code from pasted JSON and works offline without sending sample data over the Internet, a meaningful advantage for privacy-conscious work. The CLI can generate from files, URLs, directories of samples, or standard input, so it can fit into build pipelines, CI jobs, and git hooks. CLI and Node.js package use require Node.js 20 or newer, which may rule out environments that cannot meet that runtime requirement.

A hosted MCP endpoint connects quicktype to Claude Code, Cursor, Codex, and other MCP clients without an API key. This gives developers another way to bring typed data generation into AI-assisted coding workflows. The project also has a Slack community for help and discussion.

Pricing

The open-source Apache-2.0 project has a free plan at free, including the web app, CLI, community Slack, and Apache2 license. It is the natural choice for individual developers and teams who need core generation without paid support.

The 1 target language plan costs $19 a month, billed annually, and adds email support and 30 minutes of technical planning. It fits a team that wants guidance around one target language and can commit to annual billing. The 2 target languages plan costs $129 a month and adds chat support, 7-day hotfixes, and two hours of technical planning. That tier is aimed at teams needing faster support across two languages; the substantially higher price is difficult to justify if the free tools meet the need. No seat or generation quota is stated for these plans.

Platforms

quicktype is available across API, Linux, macOS, web, and Windows. The browser app suits quick conversions, while the CLI serves local and automated workflows. Node.js 20 or newer is required for the CLI and Node.js packages.

Who it's for

Choose quicktype when API or schema data needs to become typed application models, serializers, or validators, especially when a team benefits from generated code in its existing language or from using the CLI in automation. The free browser app is a strong starting point for occasional conversions, and the CLI is better for repeatable generation. Look elsewhere if the requirement is complete project scaffolding rather than models and related code.

Pros and cons

• Pros: Broad inputs and inference handle more than simple JSON field extraction, including unions, nullability, enums, dates, and UUIDs.
• Pros: Browser, CLI, and MCP access support both manual and automated coding workflows.
• Pros: Offline browser use that does not transmit sample data is useful when working with sensitive examples.
• Cons: CLI and package workflows require Node.js 20 or newer, creating a runtime constraint for some environments.
• Cons: It generates models and supporting code but does not scaffold projects, so larger setup tasks need another tool.
• Cons: Paid support plans rise sharply from $19 a month billed annually to $129 a month, which may not suit teams that only need generation.

Alternatives

For a different kind of code generation, SQLDelight is a free, open-source Kotlin SQL code generation library, suited to database-focused work. Angular CLI is another free option for developers working in Angular's ecosystem. Fern offers a free tier with team, page, AI credit, generation, and site limits, making it an alternative to assess for API-related workflows. Hygen is a free code generator distributed through npm, Homebrew, npx, and standalone binaries. Nx has a free Hobby plan with monthly credits, contributor and CI connection caps, and community support. Spring Initializr is a free, Apache 2.0 open-source option. Swagger Codegen generates API clients, server stubs, and documentation from OpenAPI specifications. ts-proto is a free, Apache-2.0 licensed repository. Browse more tools in Code Generators.

Verdict

quicktype is a strong choice for developers who need to turn representative data or schemas into typed models and serialization or validation code, particularly when they value its free browser and CLI or want generation in an automated workflow. Its broad inference, language support, and privacy-preserving offline web app are compelling strengths. Choose another tool if you need project scaffolding, cannot use Node.js 20 for command-line work, or want a broader code-generation workflow.