quicktype

quicktype turns JSON and schema inputs into typed models and supporting code for developers building around structured data. It is best for teams that need language-specific models, serialization, or validation without building a broader application scaffold. Its browser app and CLI are free and open source; paid plans add target-language support and technical help.

Overview

Rather than translate data fields by hand, developers can supply examples or a schema and generate code in a chosen language. The resulting types can support API clients, help teams catch changes in API data, and give IDEs and AI agents a typed model to work with. The project says it has more than 200 contributors and has been used to generate billions of lines of code.

Use quicktype in a browser, from the CLI, or through a hosted MCP endpoint that connects to Claude Code, Cursor, Codex, and other MCP clients without an API key. The endpoint is https://mcp.quicktype.io/mcp.

Key features

Infers structure from data and schemas

Inputs include sample JSON, API URLs, JSON Schema, TypeScript, and GraphQL queries. quicktype can infer optional and nullable properties, numeric types, dates, UUIDs, enums, unions, maps, nested type names, and equivalent structures. That makes it more useful than a field-name translator when the shape of the data carries meaningful distinctions. The output still depends on the examples or schema supplied.

Generates models and data-handling code

Generated code can include types alongside serializers and runtime validation, covering reading, writing, and checking data in the target language. With more than 25 supported languages, it suits projects that need generated representations in different language ecosystems. It does not provide project scaffolding, so teams looking for a generator that lays out a broader application need another tool.

Browser, CLI, and MCP access

The browser app generates code from pasted JSON and works offline without sending sample data over the Internet, a useful privacy property for sensitive examples. The CLI accepts files, URLs, directories of samples, or standard input, making it the stronger fit for repeatable generation in build pipelines, CI jobs, or git hooks. CLI and Node.js package users need Node.js 20 or newer. The hosted MCP endpoint offers a route into MCP-compatible clients without an API key.

Pricing

The FREE plan costs free and includes the web app, CLI, community Slack, and Apache-2.0 licensing. It is the practical starting point for individuals and teams comfortable with community support and the open-source tools.

The 1 target language plan costs $19 a month, billed annually. It adds email support and 30 minutes of technical planning, making it a focused option for a project that needs one target language and a route to technical guidance. The 2 target languages plan costs $129 a month and adds chat support, seven-day hotfixes, and two hours of technical planning. It is aimed at teams that need two target languages and more responsive support. The plan terms do not state a billing interval for the latter, so confirm that before committing.

The paid plans are less attractive if you need many target languages: the free plan includes the web app and CLI, while the paid tiers are framed around one or two target languages and support. There are no project-scaffolding features in this product.

Platforms

quicktype is available on the web and for Linux, macOS, and Windows, with API access also listed. The web app is usable offline. The CLI and Node.js packages require Node.js 20 or newer, which is a meaningful setup constraint on machines that do not already meet that runtime requirement.

Who it's for

Choose quicktype if you need to turn JSON, schemas, or API data into language-specific models and related serialization or validation code, especially when you want browser-based use, a command-line workflow, or integration with an MCP client. It is less suitable when your priority is full project scaffolding rather than data-model generation.

Pros and cons

Pros: The free, open-source browser app and CLI cover both ad hoc generation and pipeline use without a paid entry tier.

Pros: Inference spans nullability, enums, dates, UUIDs, unions, maps, and other structures, while output can include serialization and runtime validation.

Pros: Offline browser use that does not transmit sample data is a practical advantage for private examples.

Cons: CLI use requires Node.js 20 or newer, adding a prerequisite for teams whose environments do not already use it.

Cons: It does not scaffold projects, limiting its role to data-to-code generation rather than broader application setup.

Cons: The paid plans distinguish support and target-language counts, so teams needing more than two target languages may find those tiers do not match their needs.

Alternatives

For a wider set of code-generation tools, browse Code Generators. Consider Nx instead if you want a freemium tool with a free Hobby plan that includes 50,000 monthly-reset credits, five contributors, and ten concurrent CI connections. SQLDelight is a free, open-source Kotlin SQL code-generation library, a more specific fit when the task is SQL code generation in Kotlin.

Fern offers a free tier with team, page, AI-credit, page-generation, and site allowances. Stainless has a free tier for up to five generators and five seats, with endpoint and preview-build limits. TypeSpec is a free, Microsoft-built, community-supported project. JHipster is a free, open-source development platform. OpenAPI Generator is a free, open-source generator for API clients, server stubs, documentation, and configurations. Angular CLI is a free option with no paid plans or usage limits stated on its official pages.

Verdict

quicktype is a strong choice for developers who need to turn representative data into typed models, serializers, and validators across multiple languages. Its free, open-source browser app and CLI are the main reasons to choose it; look elsewhere if you need project scaffolding or a paid plan clearly suited to more than two target languages.