JSON to Elixir Map/Struct Converter

Paste JSON, get Elixir maps or defstruct modules — typespecs, from_map/1 — copy or download as .ex

All processing happens in your browser. No data is sent to any server.

Options

Module name:

Generate structAdd @type spec

JSON Input

Elixir Output

defmodule Root do
  @type t :: %__MODULE__{
    id: integer(),
    name: String.t(),
    email: String.t(),
    age: integer(),
    is_active: boolean(),
    score: float(),
    address: map(),
    tags: list(String.t()),
    posts: list(map())
  }

  defstruct [:id, :name, :email, :age, :is_active, :score, :address, :tags, :posts]

  @doc "Creates a new struct from a map."
  @spec new(map()) :: t()
  def new(attrs \\ %{}) do
    struct(__MODULE__, attrs)
  end
end

defmodule Root.Address do
  @type t :: %__MODULE__{
    street: String.t(),
    city: String.t(),
    zip: String.t()
  }

  defstruct [:street, :city, :zip]

  @doc "Creates a new struct from a map."
  @spec new(map()) :: t()
  def new(attrs \\ %{}) do
    struct(__MODULE__, attrs)
  end
end

defmodule Root.Post do
  @type t :: %__MODULE__{
    id: integer(),
    title: String.t(),
    published: boolean()
  }

  defstruct [:id, :title, :published]

  @doc "Creates a new struct from a map."
  @spec new(map()) :: t()
  def new(attrs \\ %{}) do
    struct(__MODULE__, attrs)
  end
end

Output: 1,060 charsMode: StructTypespec: enabled

You’re building a Phoenix API client and need to work with JSON responses. Elixir’s pattern matching works great with maps, but for complex nested data, defstruct modules give you compile-time guarantees and cleaner function signatures.

What This Tool Does

Paste JSON and get Elixir code instantly — either plain maps with atom keys, or full defstruct module definitions with @type typespecs and from_map/1 constructor functions. Nested objects become nested modules.

Everything runs in your browser. Your data never leaves your device.

When to Use This

Phoenix API integration — generate structs for JSON responses from external services
Ecto schema reference — use generated structs as a starting point for Ecto embedded schemas
GenServer state — define typed state structs from configuration JSON
Data pipeline processing — convert JSON schemas into Elixir structs for ETL pipelines

Map vs Struct Output

Map output gives you an Elixir map literal with atom keys — useful for quick prototyping or IEx exploration.

Struct output generates full modules with:

defstruct with all fields and defaults
@type t() typespec for Dialyzer
from_map/1 function for constructing structs from decoded JSON

FAQ

Does this send my JSON to a server?

No. All processing happens entirely in your browser.

How are nested objects handled?

Each nested JSON object becomes its own Elixir module with defstruct. Module names are derived from the parent module and the field key.

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