Schema Infer

Free online JSON schema generator that infers field types and required keys from sample payloads.

Infer JSON schema

JSON sample(s)

Samples parsed

Inferred schema

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "id": {
      "type": "integer"
    },
    "name": {
      "type": "string"
    },
    "tags": {
      "type": "array",
      "items": {
        "type": "string"
      }
    },
    "active": {
      "type": "boolean"
    }
  },
  "additionalProperties": false,
  "required": [
    "id",
    "name"
  ]
}

What problem does this tool solve?

When API contracts are undocumented, teams waste time reverse-engineering structure before validation can start.

How to use Schema Infer

Paste representative JSON samples from your API or data pipeline.
Infer field types, optional fields, and nested object structure.
Review the generated schema and tighten constraints before production use.

FAQ: Schema Infer

Can Schema Infer detect optional fields automatically?

Yes. Optionality is inferred from whether fields appear consistently across samples.

Is generated JSON schema ready for production immediately?

Treat it as a draft and add explicit constraints, enums, and business validations.

Does schema inference support nested arrays and objects?

Yes. Nested object and array structures are included in the inferred schema output.