diff --git a/doc/grammar-schema.json b/doc/grammar-schema.json
new file mode 100644
index 00000000..9fc50189
--- /dev/null
+++ b/doc/grammar-schema.json
@@ -0,0 +1,256 @@
+{
+  "type": "object",
+
+  "required": [
+    "name",
+    "rules"
+  ],
+
+  "additionalProperties": false,
+
+  "properties": {
+    "name": {
+      "type": "string",
+      "pattern": "^[a-zA-Z_]\\w*"
+    },
+
+    "rules": {
+      "type": "object",
+      "patternProperties": {
+        "^[a-zA-Z_]\\w*$": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "additionalProperties": false
+    },
+
+    "extras": {
+      "type": "array",
+      "items": {
+        "$ref": "#/definitions/rule"
+      }
+    },
+
+    "conflicts": {
+      "type": "array",
+      "items": {
+        "type": "array",
+        "items": {
+          "type": "string",
+          "pattern": "^[a-zA-Z_]\\w*$"
+        }
+      }
+    }
+  },
+
+  "definitions": {
+    "blank-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^BLANK$"
+        }
+      },
+      "required": ["type"]
+    },
+
+    "string-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^STRING$"
+        },
+        "value": {
+          "type": "string"
+        }
+      },
+      "required": ["type", "value"]
+    },
+
+    "pattern-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^PATTERN$"
+        },
+        "value": {"type": "string"}
+      },
+      "required": ["type", "value"]
+    },
+
+    "symbol-rule": {
+      "required": ["name"],
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^SYMBOL$"
+        },
+        "name": {"type": "string"}
+      },
+      "required": ["type", "name"]
+    },
+
+    "seq-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^SEQ$"
+        },
+        "members": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/rule"
+          }
+        }
+      },
+      "required": ["type", "members"]
+    },
+
+    "choice-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^CHOICE$"
+        },
+        "members": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/rule"
+          }
+        }
+      },
+      "required": ["type", "members"]
+    },
+
+    "repeat-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^REPEAT$"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content"]
+    },
+
+    "repeat1-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^REPEAT1$"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content"]
+    },
+
+    "token-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^TOKEN$"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content"]
+    },
+
+    "error-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^ERROR$"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content"]
+    },
+
+    "prec-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^PREC$"
+        },
+        "value": {
+          "type": "integer"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content", "value"]
+    },
+
+    "prec-left-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^PREC_LEFT$"
+        },
+        "value": {
+          "type": "integer"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content", "value"]
+    },
+
+    "prec-right-rule": {
+      "type": "object",
+      "properties": {
+        "type": {
+          "type": "string",
+          "pattern": "^PREC_RIGHT$"
+        },
+        "value": {
+          "type": "integer"
+        },
+        "content": {
+          "$ref": "#/definitions/rule"
+        }
+      },
+      "required": ["type", "content", "value"]
+    },
+
+    "rule": {
+      "oneOf": [
+        { "$ref": "#/definitions/blank-rule" },
+        { "$ref": "#/definitions/string-rule" },
+        { "$ref": "#/definitions/pattern-rule" },
+        { "$ref": "#/definitions/symbol-rule" },
+        { "$ref": "#/definitions/seq-rule" },
+        { "$ref": "#/definitions/choice-rule" },
+        { "$ref": "#/definitions/repeat1-rule" },
+        { "$ref": "#/definitions/repeat-rule" },
+        { "$ref": "#/definitions/token-rule" },
+        { "$ref": "#/definitions/error-rule" },
+        { "$ref": "#/definitions/prec-rule" },
+        { "$ref": "#/definitions/prec-left-rule" },
+        { "$ref": "#/definitions/prec-right-rule" }
+      ]
+    }
+  }
+}