JSON to Mongoose Schema Generator Online

How to use the JSON to Mongoose Schema

Paste a sample JSON document, for example one exported from MongoDB Compass.

Enter the Model name you want, such as User or Order.

Tick Mark fields required, timestamps: true or ES module syntax as needed.

Click Generate schema and copy the result into your models folder.

JSON to Mongoose schema in one click

This JSON to Mongoose schema generator infers a schema from one real document instead of making you type every field by hand. Paste a record from your API, a fixture or a mongosh query result, and you get a new mongoose.Schema({...}) definition plus the mongoose.model() export, ready to drop into a Node.js project.

What is a Mongoose schema?

MongoDB itself does not enforce a structure on documents. Mongoose adds one in your application: a schema declares each field's type, which fields are required, defaults and references. Mongoose uses it to cast values (for example the string "31" to the number 31), validate writes and populate related documents.

Example

Input document:

{"_id": "65f1c0a2b3d4e5f6a7b8c9d0","name": "Ann Lee","email": "ann@example.com","tags": ["admin", "beta"],"address": { "city": "Paris", "zip": "75001" },"orders": [{ "sku": "A1", "qty": 2 }],"managerId": "65f1c0a2b3d4e5f6a7b8c9d1","createdAt": "2024-03-01T10:00:00Z","updatedAt": "2024-03-02T10:00:00Z"}

Generated schema with the default options:

const mongoose = require('mongoose');const userSchema = new mongoose.Schema({name: String,email: String,tags: [String],address: {city: String,zip: String,},orders: [{sku: String,qty: Number,}],managerId: mongoose.Schema.Types.ObjectId,}, { timestamps: true });module.exports = mongoose.model('User', userSchema);

How types are detected

JSON value	Mongoose type
24-character hex string	`mongoose.Schema.Types.ObjectId`
ISO date string, like `2024-03-01` or `2024-03-01T10:00:00Z`	`Date`
Other string	`String`
Number	`Number`
`true` / `false`	`Boolean`
Nested object	Nested path object
Array	`[Type]`; arrays of objects merge all keys into one subdocument shape
`null` or empty array	`Mixed` / `[Mixed]`

The _id and __v fields are removed, because Mongoose adds them itself. When the document has both createdAt and updatedAt, those fields are removed too and { timestamps: true } is added, which tells Mongoose to maintain them automatically.

Options explained

Model name: sets the model and schema variable names. Mongoose derives the collection name by lowercasing and pluralizing it, so User is stored in users.
Mark fields required: writes each scalar field as { type: String, required: true }. It also adds lowercase: true, trim: true to email fields and a ref to ObjectId fields ending in Id, so managerId gets ref: 'Manager' for use with populate().
timestamps: true: adds the timestamps option even when the sample has no date fields.
ES module syntax: switches from require and module.exports to import and export default.

Tips and limitations

The schema can only be as good as the sample. A field that is null in your document becomes Mixed, and a field that is missing will not appear at all, so pick a complete, representative record. If you paste an array of documents, their keys are merged so optional fields from any record are included.

Indexes, unique constraints, enums, min/max validators and defaults are not inferred. Add them after generating. Also check ref names: managerId may actually point to a User model rather than Manager.

Privacy

The schema is generated in your browser, so customer records you paste never leave your device. Related tools: generate TypeScript types for the same document with JSON to TypeScript, translate SQL queries with SQL to MongoDB, or build a validation schema with JSON to Zod.

Frequently asked questions

How does the generator know a string is an ObjectId?

Any string of exactly 24 hexadecimal characters is typed as mongoose.Schema.Types.ObjectId. That matches how ObjectIds look in exported JSON. If a field only looks like an id by coincidence, change it back to String.

Can I paste Extended JSON with $oid and $date?

Extended JSON wrappers like {"$oid": "..."} are treated as nested objects. Export or paste relaxed JSON instead, or replace the wrappers with plain strings, so the ObjectId and Date detection works.

Does it generate TypeScript types for Mongoose?

No, the output is a JavaScript schema. With Mongoose 6 and later you can let TypeScript infer the document type from the schema, or generate an interface separately with the JSON to TypeScript tool.

Why are createdAt and updatedAt missing from my schema?

When both fields are present, the generator uses { timestamps: true } instead. Mongoose then creates and updates those two fields for you, which is more reliable than setting them by hand.

How are arrays of objects handled?

The keys of every object in the array are merged into one subdocument definition, like [{ sku: String, qty: Number }]. Each element then becomes a subdocument with its own _id unless you disable that in Mongoose.