Paste raw JSON from REST APIs or GraphQL endpoints to instantly synthesize production-grade type definitions. Automatically resolves nested objects, array element unions, optional fields, integer vs float numerals, and ISO 8601 date strings.
AST Type Inference & Multi-Target Schema Synthesis
Technical guide on JSON syntax tree parsing, recursive structural typing, and runtime schema generation.
Architecture Overview
Modern distributed architectures communicate via dynamic JSON over HTTP. Manually translating un-typed JSON payload samples into static language types is error-prone and leads to runtime crashes when API schemas shift. This engine parses raw JSON into an Abstract Syntax Tree (AST), infers structural types, union primitives, and optionality, and synthesizes compile-time type definitions and runtime validation schemas.
Core Mechanics & Implementation Details
Lexical Parsing & AST Construction
The input string is processed through a deterministic JSON parser to validate syntax and produce an in-memory object tree. The type inferer recursively inspects node values: boolean, integer, float, string, array, object, and null. ISO 8601 timestamps are detected via regex to generate strict datetime types where supported.
Array Union & Heterogeneous Element Resolution
Real-world JSON arrays frequently contain heterogeneous items. The inferer iterates across all array elements to construct a unified type signature. If an array contains objects with differing property sets, the synthesizer computes a merged schema with optional fields (e.g. { id: number; tag?: string }[]).
Multi-Target Code Generation
The normalized structural schema is mapped to target language constructs: TypeScript uses interfaces with optional modifiers (?); Zod compiles declarative chains (z.object({ id: z.number() })); Go maps PascalCase fields with struct tags (`json:"id"`); and Rust emits Serde-annotated structs (#[serde(rename = "...")]).
Engineering Specifications
Parameter
Standard / Value
Engineering Scope
Input Standard
IETF RFC 8259 JavaScript Object Notation
Universal data-interchange syntax
TypeScript Target
TypeScript 5.x Interface / Type Alias
Compile-time structural type checker
Runtime Validator
Zod v3+ Schema Definition
Zero-dependency runtime schema validation
Systems Languages
Go 1.22+ Struct & Rust Serde 1.0+
Strict typed backend model generation
Date Detection
ISO 8601 (YYYY-MM-DDTHH:mm:ssZ)
Temporal string pattern recognition
Recommended Best Practices
•Use Zod schemas on API boundaries to validate untrusted incoming payloads before passing to internal handlers.
•Review generated numeric types in Go and Rust to ensure int64 vs float64 matches database column definitions.
•Export generated types into a shared types package or mono-repo contracts directory for full-stack consistency.
Common Pitfalls & Anti-Patterns
•Assuming an empty array [] has a specific element type; the inferer defaults to unknown[] or any[].
•Forgetting that JSON keys with hyphens or symbols require quote wrapping in TypeScript and custom rename tags in Go/Rust.