plymove.com

{
  "type": "object",
  "properties": {
    "fen": {
      "type": "string",
      "minLength": 15,
      "maxLength": 100,
      "pattern": "^([rnbqkpRNBQKP1-8]+\\/){7}[rnbqkpRNBQKP1-8]+ [wb] ([KQkq]+|-) ([a-h][36]|-) \\d+ \\d+$",
      "description": "Chess position in standard FEN (six fields: piece placement, active color, castling, en passant, halfmove, fullmove)."
    },
    "moves": {
      "type": "array",
      "items": {
        "type": "string",
        "minLength": 2,
        "maxLength": 10,
        "pattern": "^(O-O(-O)?[+#]?|[NBRQK]?[a-h]?[1-8]?x?[a-h][1-8](=[NBRQ])?[+#]?)$",
        "description": "One move in Standard Algebraic Notation (SAN), e.g. Nf3, exd5, O-O. Not UCI."
      },
      "minItems": 2,
      "maxItems": 8,
      "description": "Two or more candidate moves in SAN (not UCI)."
    },
    "target_elo": {
      "type": "integer",
      "minimum": 400,
      "maximum": 3500,
      "description": "Target learner Elo (400–3500)."
    }
  },
  "required": [
    "fen",
    "moves",
    "target_elo"
  ],
  "additionalProperties": false
}