JSON to Haskell Converter

How to use

1. Paste a representative JSON payload that reflects the response or document shape your Haskell code actually decodes.
2. Review the generated `data` declarations, derived instances, and inferred `Maybe` or list fields.
3. Copy the output into your project and refine module names, deriving clauses, or custom parsing where production code needs them.

Benefits

• Produces Haskell data types that fit Aeson-style decoding workflows without starting from a blank module.
• Keeps nested payloads readable through explicit typed records instead of generic `Value` traversal.
• Gives functional codebases a strong transport-model starting point before domain-specific refinement.

Best use cases

• Haskell services that decode external API payloads with Aeson.
• CLI tools and data jobs that parse JSON config or event data into typed records.
• Teams moving from loose JSON exploration to explicit functional data models.

Haskell data-type tips

• Review `Maybe` fields and collection shapes against real payload samples before treating generated types as stable contracts.
• Add custom FromJSON logic later only when the payload needs nonstandard decoding behavior.
• Keep generated transport types separate from richer domain models when invariants grow beyond the payload shape.

Sample JSON

{
  "id": 101,
  "name": "Ada Lovelace",
  "active": true,
  "roles": ["admin", "editor"],
  "profile": {
    "email": "ada@example.com",
    "score": 9.8
  }
}

Sample Haskell output

{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics (Generic)
import Data.Text (Text)
import Data.Aeson (FromJSON, ToJSON)

data UserModel = UserModel
  { id :: Int
  , name :: Text
  , active :: Bool
  }
  deriving (Show, Eq, Generic)

instance FromJSON UserModel
instance ToJSON UserModel

FAQ