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JSON to JSON Schema Generator

Create a reviewable first draft of a JSON Schema from example data. Select the dialect your validator expects and inspect required fields, formats, nulls and literals before treating it as a contract.

Read the full guide

Direct answer

JSON Schema describes and validates the expected shape of JSON. A generator can infer types and observed formats from samples, but unobserved optional fields, unions and constraints must be added by a human.

Select the target dialect, generate the draft and validate it with the same engine used in production.

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Input JSON

Example JSON loaded.
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Output JSON Schema

1{2  "$schema": "http://json-schema.org/draft-07/schema#",3  "type": "object",4  "properties": {5    "user": {6      "type": "object",7      "properties": {8        "id": {9          "type": "integer",10          "examples": [11            112          ],13          "description": "Id field."14        },15        "name": {16          "type": "string",17          "examples": [18            "John"19          ],20          "description": "Name field."21        },22        "email": {23          "type": "string",24          "format": "email",25          "examples": [26            "[email protected]"27          ],28          "description": "Email field."29        },30        "isActive": {31          "type": "boolean",32          "examples": [33            true34          ],35          "description": "IsActive field."36        },37        "roles": {38          "type": "array",39          "items": {40            "anyOf": [41              {42                "type": "string",43                "examples": [44                  "admin"45                ]46              },47              {48                "type": "string",49                "examples": [50                  "editor"51                ]52              }53            ]54          },55          "examples": [56            [57              "admin",58              "editor"59            ]60          ],61          "description": "Roles field."62        },63        "profile": {64          "type": "object",65          "properties": {66            "age": {67              "type": "integer",68              "examples": [69                3070              ],71              "description": "Age field."72            },73            "address": {74              "type": "object",75              "properties": {76                "city": {77                  "type": "string",78                  "examples": [79                    "New York"80                  ],81                  "description": "City field."82                },83                "zip": {84                  "type": "string",85                  "examples": [86                    "10001"87                  ],88                  "description": "Zip field."89                }90              },91              "required": [92                "city",93                "zip"94              ],95              "description": "Address field."96            }97          },98          "required": [99            "age",100            "address"101          ],102          "description": "Profile field."103        },104        "lastLogin": {105          "type": "string",106          "format": "date-time",107          "examples": [108            "2024-03-18T10:24:00Z"109          ],110          "description": "LastLogin field."111        },112        "homepage": {113          "type": "string",114          "format": "uri",115          "examples": [116            "https://example.com"117          ],118          "description": "Homepage field."119        }120      },121      "required": [122        "id",123        "name",124        "email",125        "isActive",126        "roles",127        "profile",128        "lastLogin",129        "homepage"130      ],131      "description": "User field."132    }133  },134  "required": [135    "user"136  ]137}

How to use it

  1. Paste/upload JSON or fetch a supported public sample.
  2. Choose the JSON Schema draft and configure type mapping, descriptions, examples, required inference, const and null behavior.
  3. Inspect raw/tree output, validate it with the target validator and copy/download the schema.

Key features and settings

  • Draft selection from legacy drafts through 2020-12 in the current UI.
  • Smart/strict/loose type-mapping controls.
  • Descriptions, examples, required inference, const and null options.
  • Raw schema and tree views for review.

Supported input and output

Input: JSON text or file, a supported public URL. Output: JSON Schema text or file.

Use cases

  • Bootstrap API response/request validation.
  • Document fixtures and exported record shapes.
  • Create a starting schema for UI generation or contract tests.

Which workflow should you choose?

Use JSON to JSON Schema Generator for: Draft selection from legacy drafts through 2020-12 in the current UI. Use JSON to Function Calling Schema Generator for: Targets currently shown: OpenAI, Claude and Gemini.

Privacy and data path

In the current implementation, pasted/uploaded content is processed in the browser, while “Extract from URL” uses a server-side proxy to fetch the source.

Limits and troubleshooting

  • OpenAPI 3.1 aligns with JSON Schema Draft 2020-12 semantics; match the exact dialect supported by the downstream toolchain.
  • A single sample makes every present property look required unless the setting is changed; use representative samples and contract knowledge.
  • The current UI displays a 5 MB input limit.

FAQ

Which JSON Schema draft should I choose?

Choose the dialect required by the actual validator or platform. Draft 2020-12 is the latest published JSON Schema version, but legacy systems may require an older draft.

Is my data uploaded to a server?

In the current implementation, pasted/uploaded content is processed in the browser, while “Extract from URL” uses a server-side proxy to fetch the source.

What are the file or data limits?

The current UI displays a 5 MB input limit.

Does it work on mobile?

The page is web-based and may work in a modern mobile browser, but file-picker behavior, memory and cross-device compatibility are not verified for every device. Use a desktop browser for large or complex inputs.

Which workflow should you choose?

Use JSON to JSON Schema Generator for: Draft selection from legacy drafts through 2020-12 in the current UI. Use JSON to Function Calling Schema Generator for: Targets currently shown: OpenAI, Claude and Gemini.

Related tools

JSON to Zod Schema GeneratorGenerate a starting point for runtime validation in TypeScript.JSON to Function Calling Schema GeneratorGenerate provider-specific tool/function declarations for OpenAI, Claude or Gemini.JSON Formatter OnlineFormat and validate JSON before conversion, or inspect the result afterward.

Select the target dialect, generate the draft and validate it with the same engine used in production.