Documentation

npm install -D snaptype

# TypeScript interfaces from a JSON file
snaptype from-json users.json -o src/types/user.ts

# Zod schema from a REST API response
snaptype from-url https://api.example.com/users -o src/schemas/user.ts --zod

# Both TypeScript and Zod at once
snaptype from-json data.json --zod --ts -o src/types.ts

snaptype from-json <file> [options]

# Single file
snaptype from-json data.json -o src/types/data.ts

# Override the root type name
snaptype from-json response.json --name ApiResponse -o src/types.ts

# Zod schema output
snaptype from-json data.json --zod -o src/schemas/data.ts

# Both TypeScript and Zod
snaptype from-json data.json --zod --ts -o src/types.ts

# Multiple files — merged into one unified type (Pro)
snaptype from-json sample1.json sample2.json sample3.json -o src/types.ts

snaptype from-url <url> [options]

# From a REST API
snaptype from-url https://api.github.com/users/octocat -o src/github.ts

# Custom root name
snaptype from-url https://api.example.com/me --name CurrentUser -o src/me.ts

# With authentication header
snaptype from-url https://api.example.com/me \
  -H "Authorization: Bearer $TOKEN" \
  -o src/me.ts

# Multiple endpoints merged — absent fields become optional (Pro)
snaptype from-url https://api.example.com/users/1 \
  https://api.example.com/users/2 \
  -o src/user.ts

snaptype from-csv <file> [options]

# TypeScript interfaces from CSV
snaptype from-csv data.csv -o src/types/row.ts

# Snake case property names
snaptype from-csv data.csv --naming snake -o src/types/row.ts

# File without a header row — provide column names manually
snaptype from-csv data.csv \
  --columns id,name,score,active \
  -o src/types/row.ts

# Watch mode — regenerates on every file save (Pro)
snaptype from-csv data.csv --watch -o src/types/row.ts

snaptype from-stdin --name <TypeName> [options]

# Pipe from curl
curl https://api.example.com/me | snaptype from-stdin --name CurrentUser

# Pipe from another command
cat response.json | snaptype from-stdin --name ApiResponse -o src/types.ts

# With Zod output
curl https://api.example.com/products | snaptype from-stdin --name Product --zod

snaptype from-openapi <source> [options]

# One file per schema (default) — output must be a directory
snaptype from-openapi ./openapi.yaml -o ./src/types/

# All schemas in a single file
snaptype from-openapi ./openapi.yaml --single-file -o ./src/api-types.ts

# Remote spec
snaptype from-openapi https://petstore3.swagger.io/api/v3/openapi.json -o ./types/

# With Zod schemas
snaptype from-openapi ./openapi.yaml --zod -o ./src/schemas/

snaptype from-graphql <endpoint> [options]

# Public endpoint
snaptype from-graphql https://api.example.com/graphql -o src/graphql-types/

# With authentication header
snaptype from-graphql https://api.example.com/graphql \
  -H "Authorization: Bearer $TOKEN" \
  -o src/graphql-types/

snaptype barrel <dir> [options]

# Default: outputs <dir>/index.ts
snaptype barrel ./src/types

# Custom output path
snaptype barrel ./src/types -o src/types/index.ts

# Watch mode — regenerates when files are added or removed
snaptype barrel ./src/types --watch

// Generated by snaptype — do not edit manually
export * from './user.js';
export * from './post.js';
export * from './product.js';

snaptype diff <old> <new> [options]

# Compare two versions
snaptype diff types-v1.ts types-v2.ts

# CI mode — exits with code 1 if breaking changes are found
snaptype diff old-types.ts new-types.ts --ci

Breaking changes (2):
  [breaking] User.email — field removed
  [breaking] User.role — type changed: string → "admin" | "editor"

Non-breaking changes (1):
  [ok]       User.nickname — field added

# GitHub Actions example
- name: Check for breaking type changes
  run: npx snaptype diff types/v1.ts types/v2.ts --ci
  env:
    SNAPTYPE_LICENSE_KEY: ${{ secrets.SNAPTYPE_LICENSE_KEY }}

snaptype mock <file> [options]

# JSON output (default)
snaptype mock schema.json -o mocks/data.json

# TypeScript const export
snaptype mock schema.json --ts -o mocks/data.ts

export const mockUser = {
  id: 0,
  email: "user@example.com",
  createdAt: "2024-01-01T00:00:00.000Z",
  active: true,
} as const;

snaptype to-zod <file> [options]

# Convert a file of interfaces to Zod
snaptype to-zod src/types/user.ts -o src/schemas/user.ts

# With readonly
snaptype to-zod src/types/user.ts --readonly -o src/schemas/user.ts

export interface User {
  readonly id: number;
  email: string;       // email
  createdAt: string;   // ISO 8601
  role: "admin" | "user";
}

import { z } from 'zod';

export const UserSchema = z.object({
  id: z.number(),
  email: z.email(),
  createdAt: z.iso.datetime(),
  role: z.enum(["admin", "user"]),
}).readonly();

export type User = z.infer<typeof UserSchema>;

// --emit interface (default)
export interface User { ... }

// --emit type
export type User = { ... }

{
  "naming": "camel",
  "emit": "interface",
  "zod": false,
  "outDir": "./src/types"
}

# Temporary (current session)
export SNAPTYPE_LICENSE_KEY=your-key-here

# Permanent (add to your shell profile)
echo 'export SNAPTYPE_LICENSE_KEY=your-key-here' >> ~/.zshrc