JSON Code Generator
TS · Java · Go · Type inference
Code generator
Ready
ABOUT
About JSON Code Generator
Auto-infer field types from JSON samples and generate struct or interface definitions for each language.
Type definitions are the contract between frontend and backend. Generating TypeScript / Java / Go types from real JSON samples is an order of magnitude faster than hand-writing interfaces—and avoids runtime errors from missed new fields.
DEEP DIVE
Learn More About JSON Code Generator
During API integration, frontend and backend must agree on data structures. Manually writing TypeScript interfaces, Java POJOs, or Go structs is slow and error-prone. JSONSort Code Generator infers types from JSON samples and produces paste-ready definitions in seconds.
Inference rules: string → string, number → number/int, boolean → boolean, array → []Type, object → nested structure. null values mark fields as optional or union types—matching sparse data in real APIs.
Static type inference cannot replace OpenAPI/Swagger semantic descriptions (format: date-time, enum constraints, etc.). Generated code is a "90% starting point": changing string to Date, adding enums, marking optional in IDE is inevitable.
FEATURES
Core capabilities
TypeScript
Generate interface and type definitions with nested and array types.
Java
Generate POJO classes with getter-style field declarations.
Go
Generate struct with json tags following Go conventions.
Type inference
Auto-select appropriate types from JSON values; null handled as optional.
Nested support
Deeply nested objects recursively generate sub-types / inner classes.
Local inference
API response samples never uploaded—protects API data structure privacy.
Nested type naming
Deep objects auto-generate sub-interface / inner class names.
Array element inference
Infer []Type from first non-null element; multiple samples can merge types.
HOW TO USE
How to use
-
1
Paste JSON sample
-
2
Select target language (TS / Java / Go)
-
3
Copy generated type code
-
4
Switch TS / Java / Go and other targets via output language options
-
5
Paste generated code into IDE; fine-tune naming and types per project conventions
WORKFLOW
Typical workflow
End-to-end workflow from import to export, helping teams standardize JSON Code Generator usage.
Collect samples
Copy real API responses from Network; cover all field types when possible.
Select language
TS for frontend; Java/Go for server-side DTO starting point.
Copy to IDE
After paste, run formatter; adjust semantic types like Date/enum.
Add to CI
Regenerate when samples change; Diff type definitions to catch breaking changes.
USE CASES
Use cases
Frontend developers
When Swagger is stale, generate TS types from actual responses.
Backend developers
Java/Go server-side: generate DTO starting point from JSON samples.
Full-Stack Engineer
Frontend and backend share the same JSON sample; each generates language-specific types.
Open source contribution
Quickly generate type skeleton when building SDKs for third-party APIs.
SDK author
Quickly generate client type skeleton for third-party REST APIs.
Monorepo maintenance
Share JSON samples across frontend/backend; each generates language bindings.
TIPS
Tips
- Use real API responses rather than hand-crafted samples for more accurate types.
- Include non-null representative values for each field in samples to avoid all-optional output.
- Array element types inferred from first element—ensure sample array elements have consistent structure.
- Fine-tune in IDE after generation: Date strings can become Date type, etc.
- When nesting is too deep, use path extraction to understand structure, then extract subtree to generate.
- Use with Mock tool: after generating types, create test data matching the type structure.
- Merge multiple API response samples (success/failure/pagination) for more complete union types.
- Field names with - or spaces are auto-sanitized—search and confirm after generation.
- Go struct tags include json field names—ready for encoding/json.
- After generation, link with Mock tool to ensure mock data matches type structure.
LOCAL VS ONLINE
Local vs online tools
JSONSort stays purely frontend—this comparison shows why local tools fit dev data better.
TROUBLESHOOTING
Common pitfalls & fixes
Issues you may hit in practice and how to handle them—save time on trial and error.
All fields optional
Tip:Sample values contain null; replace with representative records without null.
Wrong array type
Tip:Array element structures inconsistent; unify schema or split into union.
Reserved word conflict
Tip:Generator adds suffix; still check compile errors in IDE.
Deep nesting hard to read
Tip:Use path extraction to extract subtrees and generate sub-types separately.
FAQ
FAQ
Can it generate Python dataclass?
Currently supports TS / Java / Go. Python may be added later.
What if field name is a reserved word?
Generator auto-adds suffix or escapes, e.g. class → class_.
How are union types inferred?
When same field has multiple types, generates union (e.g. string | number).
Too many any types?
Too many nulls in sample; add responses with concrete values and regenerate.
Can it generate Zod schema?
Currently TS/Java/Go. Zod can be converted from TS types or use dedicated tools.
Is data uploaded to a server?
No. All JSONSort tools run locally in your browser—your input is never sent to any backend.
Do I need to sign up or install anything?
No. Open the page and go—no account, no client download, PWA offline cache supported.
How large can files be?
Depends on browser memory; multi-MB data usually runs smoothly. Split very large files or use merge & clean first.