quicktype

Overview

Give quicktype sample data or a schema and it infers a model for a target language. That can spare teams from manually translating API responses and help keep client code aligned with the data it consumes. The project says generated types can help teams build API clients, catch API changes, and give IDEs and AI agents a typed model of data.

It supports more than 25 languages, from C and Java to Python, Rust, Swift, and TypeScript. More than 200 contributors have contributed to the Apache-2.0 open-source project, and the official site says millions of developers have generated billions of lines of code with it.

Key features

Infers useful distinctions in data

Inputs include sample JSON, API URLs, JSON Schema, TypeScript, and GraphQL queries. quicktype can infer optional and nullable fields, numeric types, dates, UUIDs, enums, unions, maps, nested type names, and equivalent structures. That makes it more useful than a field-name converter when samples contain varied or nested data; the inferred model still depends on the examples or definitions provided.

Generates models and data-handling code

Output can include target-language types as well as code to read, write, and validate data. This is useful when a project needs more than declarations alone, though quicktype does not scaffold an entire project.

Browser, CLI, and MCP access

The browser app lets users paste JSON and generate code, and works offline without sending sample data over the Internet. For repeatable workflows, the CLI accepts files, URLs, directories of samples, or standard input, making it suitable for build pipelines, CI jobs, and git hooks. The CLI and Node.js packages require Node.js 20 or newer, a meaningful constraint for older environments.

A hosted MCP endpoint connects quicktype to Claude Code, Cursor, Codex, or any MCP client without an API key. The endpoint is https://mcp.quicktype.io/mcp. The project also directs users to a Slack community for help and discussion.

Pricing

quicktype is open source and has a free plan. The FREE plan costs 0.00 USD per free and includes the web app, CLI, community Slack, and Apache2 license. This is the natural fit for individual developers and teams comfortable relying on community support.

The 1 target language plan costs 19.00 USD per month, billed annually. It adds email support and 30 minutes of technical planning, so it may suit a team that wants help focused on one target language. The 2 target languages plan costs 129.00 USD per month and adds chat support, 7-day hotfixes, and 2 hours of technical planning; it is aimed at teams needing broader language coverage and faster support. The paid plans trade the free community-support model for progressively more assistance. Their published terms do not state seat or usage caps.

Platforms

quicktype is available on the web and as a CLI for Linux, macOS, and Windows. Its API and IDE-plugin support also make it relevant to developer workflows beyond the browser interface.

Who it's for

Choose quicktype when you need to turn representative data or schemas into models and serialization or validation code, especially across multiple target languages. The browser app suits occasional conversion, while the CLI fits teams automating generation in development and delivery workflows. It is less suitable when the goal is full application or project scaffolding rather than data-to-code generation.

Pros and cons

• Pros: Broad input and language support lets teams generate models from several common data definitions without committing to one target language.
• Pros: Serialization and runtime validation output can cover practical data handling beyond type declarations.
• Pros: Offline browser use and the CLI's file, URL, directory, and standard-input options support both private sample data and automated workflows.
• Cons: The CLI and Node.js packages require Node.js 20 or newer, which can rule it out in older runtime environments.
• Cons: It does not provide project scaffolding, so teams seeking a generator for complete application structure need another tool.
• Cons: The paid plans cost more as support and language coverage expand; the free plan relies on community Slack support.

Alternatives

For other tools in this category, see Code Generators.

• JHipster is a free, open-source development platform; choose it when that broader platform scope matters more than quicktype's focused data-to-code generation.
• Micronaut Launch is a free alternative for readers comparing development tooling in this space.
• Nx suits teams seeking a freemium tool with a free Hobby plan that includes 50,000 monthly-reset credits, five contributors, and 10 concurrent CI connections.
• OpenAPI Generator is a free, open-source generator for API clients, server stubs, documentation, and configurations; choose it when those OpenAPI-oriented outputs are the goal.
• Speakeasy may suit teams seeking SaaS catalog integrations, custom server creation, an OAuth 2.1 proxy with DCR, real-time logs, and SLA-backed support; its Enterprise pricing is tailored.
• TypeSpec is a free, open-source, Microsoft-built project with community support for readers considering another open-source option.
• Backstage is a free open-source framework for teams looking beyond a dedicated data-to-code generator.
• sqlc offers a free command-line tool; choose it when a CLI is the relevant comparison, noting that hosted sqlc Cloud features require a cloud project.

Verdict

quicktype is a strong choice for developers who need typed models plus serialization and validation code from JSON, schemas, or GraphQL, with a useful free browser app and automation-ready CLI. Its chief reason to choose is the combination of broad inference, language coverage, and open-source access; look elsewhere for project scaffolding or if Node.js 20 is not available for command-line use.