diff --git a/README.md b/README.md
index c6f5666..95bfbba 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,7 @@ By default, it is able to stringify and parse objects that contains `BigInt` num
 
 * [Installation](#installation)
 * [Example of use](#example-of-use)
+* [Using CircularJSON](#using-circularjson)
 * [Adding custom types](#adding-custom-types)
 * [Contributing](#contributing)
 * [Code of Conduct](#code-of-conduct)
@@ -30,6 +31,20 @@ const str = Vilanova.stringify(obj);
 const newObj = Vilanova.parse(str);
 ```
 
+## Using CircularJSON
+
+Vilanova allows you to use your own stringify and parse functions. One of the most used is CircularJSON.
+
+```javascript
+const CircularJSON = require('circular-json');
+const Vilanova = require('vilanova');
+
+const obj = { id: 1, name: 'name', value: 123456789012345678901234567890n };
+const str = Vilanova.stringify(obj, CircularJSON.strinfigy);
+const newObj = Vilanova.parse(str, CircularJSON.parse);
+```
+
+
 ## Adding custom types
 
 To add a custom type, you can use `Vilanova.addType` method. You must provide the name of the type, the reviver function and the replacer function.
diff --git a/lib/index.js b/lib/index.js
index e0e0509..8d29463 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -9,7 +9,7 @@ class Vilanova {
    * @param {Function} reviver - Function for the reviver of this type.
    */
   static addType(name, replacer, reviver) {
-    Vilanova.types[name.toLowerCase()] = { replacer, reviver };
+    Vilanova.types[name] = { replacer, reviver };
   }
 
   /**
@@ -17,7 +17,7 @@ class Vilanova {
    */
   static addDefaultTypes() {
     // eslint-disable-next-line
-    Vilanova.addType('bigint', value => `#BigInt:${value}`, value => BigInt(value));
+    Vilanova.addType('bigint', value => `#bigint:${value}`, value => BigInt(value));
   }
 
   /**
@@ -29,7 +29,7 @@ class Vilanova {
    * @returns {Object} Stringified version or the source object.
    */
   static replacer(key, value) {
-    const type = Vilanova.types[(typeof value).toLowerCase()];
+    const type = Vilanova.types[(typeof value)];
     if (type) {
       return type.replacer(value);
     }
@@ -40,10 +40,12 @@ class Vilanova {
    * Converts a JavaScript value to a JSON string, using replacers for types
    * that can be intercepted.
    * @param {Object} obj - Input object.
+   * @param {Function} fn - Function that performs the stringify, undefined for JSON.stringify.
    * @returns {String} Stringified version of the object.
    */
-  static stringify(obj) {
-    return JSON.stringify(obj, Vilanova.replacer);
+  static stringify(obj, fn) {
+    const stringifyFn = fn || JSON.stringify;
+    return stringifyFn(obj, Vilanova.replacer);
   }
 
   /**
@@ -78,18 +80,23 @@ class Vilanova {
     }
     const token = Vilanova.getToken(value);
     if (token.type) {
-      const type = Vilanova.types[token.type.toLowerCase()];
+      const type = Vilanova.types[token.type];
       if (type) {
         return type.reviver(token.value);
       }
     }
     return value;
   }
+
   /**
    * Parses a JSON string, constructing the JavaScript value or object described by the string.
+   * @param {String} str - String to be parsed.
+   * @param {Function} fn - Function for the parse, undefined for default JSON.parse.
+   * @returns {Object} The object parsed from the string.
    */
-  static parse(str) {
-    return JSON.parse(str, Vilanova.reviver);
+  static parse(str, fn) {
+    const parseFn = fn || JSON.parse;
+    return parseFn(str, Vilanova.reviver);
   }
 }
 
diff --git a/package-lock.json b/package-lock.json
index da014f7..bc83ce7 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,56 +13,6 @@
         "@babel/highlight": "7.0.0-rc.1"
       }
     },
-    "@babel/generator": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/generator/-/generator-7.0.0-beta.44.tgz",
-      "integrity": "sha512-5xVb7hlhjGcdkKpMXgicAVgx8syK5VJz193k0i/0sLP6DzE6lRrU1K3B/rFefgdo9LPGMAOOOAWW4jycj07ShQ==",
-      "dev": true,
-      "requires": {
-        "@babel/types": "7.0.0-beta.44",
-        "jsesc": "^2.5.1",
-        "lodash": "^4.2.0",
-        "source-map": "^0.5.0",
-        "trim-right": "^1.0.1"
-      },
-      "dependencies": {
-        "jsesc": {
-          "version": "2.5.1",
-          "resolved": "https://registry.npmjs.org/jsesc/-/jsesc-2.5.1.tgz",
-          "integrity": "sha1-5CGiqOINawgZ3yiQj3glJrlt0f4=",
-          "dev": true
-        }
-      }
-    },
-    "@babel/helper-function-name": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/helper-function-name/-/helper-function-name-7.0.0-beta.44.tgz",
-      "integrity": "sha512-MHRG2qZMKMFaBavX0LWpfZ2e+hLloT++N7rfM3DYOMUOGCD8cVjqZpwiL8a0bOX3IYcQev1ruciT0gdFFRTxzg==",
-      "dev": true,
-      "requires": {
-        "@babel/helper-get-function-arity": "7.0.0-beta.44",
-        "@babel/template": "7.0.0-beta.44",
-        "@babel/types": "7.0.0-beta.44"
-      }
-    },
-    "@babel/helper-get-function-arity": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/helper-get-function-arity/-/helper-get-function-arity-7.0.0-beta.44.tgz",
-      "integrity": "sha512-w0YjWVwrM2HwP6/H3sEgrSQdkCaxppqFeJtAnB23pRiJB5E/O9Yp7JAAeWBl+gGEgmBFinnTyOv2RN7rcSmMiw==",
-      "dev": true,
-      "requires": {
-        "@babel/types": "7.0.0-beta.44"
-      }
-    },
-    "@babel/helper-split-export-declaration": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/helper-split-export-declaration/-/helper-split-export-declaration-7.0.0-beta.44.tgz",
-      "integrity": "sha512-aQ7QowtkgKKzPGf0j6u77kBMdUFVBKNHw2p/3HX/POt5/oz8ec5cs0GwlgM8Hz7ui5EwJnzyfRmkNF1Nx1N7aA==",
-      "dev": true,
-      "requires": {
-        "@babel/types": "7.0.0-beta.44"
-      }
-    },
     "@babel/highlight": {
       "version": "7.0.0-rc.1",
       "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.0.0-rc.1.tgz",
@@ -74,111 +24,6 @@
         "js-tokens": "^3.0.0"
       }
     },
-    "@babel/template": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/template/-/template-7.0.0-beta.44.tgz",
-      "integrity": "sha512-w750Sloq0UNifLx1rUqwfbnC6uSUk0mfwwgGRfdLiaUzfAOiH0tHJE6ILQIUi3KYkjiCDTskoIsnfqZvWLBDng==",
-      "dev": true,
-      "requires": {
-        "@babel/code-frame": "7.0.0-beta.44",
-        "@babel/types": "7.0.0-beta.44",
-        "babylon": "7.0.0-beta.44",
-        "lodash": "^4.2.0"
-      },
-      "dependencies": {
-        "@babel/code-frame": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.0.0-beta.44.tgz",
-          "integrity": "sha512-cuAuTTIQ9RqcFRJ/Y8PvTh+paepNcaGxwQwjIDRWPXmzzyAeCO4KqS9ikMvq0MCbRk6GlYKwfzStrcP3/jSL8g==",
-          "dev": true,
-          "requires": {
-            "@babel/highlight": "7.0.0-beta.44"
-          }
-        },
-        "@babel/highlight": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.0.0-beta.44.tgz",
-          "integrity": "sha512-Il19yJvy7vMFm8AVAh6OZzaFoAd0hbkeMZiX3P5HGD+z7dyI7RzndHB0dg6Urh/VAFfHtpOIzDUSxmY6coyZWQ==",
-          "dev": true,
-          "requires": {
-            "chalk": "^2.0.0",
-            "esutils": "^2.0.2",
-            "js-tokens": "^3.0.0"
-          }
-        },
-        "babylon": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/babylon/-/babylon-7.0.0-beta.44.tgz",
-          "integrity": "sha512-5Hlm13BJVAioCHpImtFqNOF2H3ieTOHd0fmFGMxOJ9jgeFqeAwsv3u5P5cR7CSeFrkgHsT19DgFJkHV0/Mcd8g==",
-          "dev": true
-        }
-      }
-    },
-    "@babel/traverse": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/traverse/-/traverse-7.0.0-beta.44.tgz",
-      "integrity": "sha512-UHuDz8ukQkJCDASKHf+oDt3FVUzFd+QYfuBIsiNu/4+/ix6pP/C+uQZJ6K1oEfbCMv/IKWbgDEh7fcsnIE5AtA==",
-      "dev": true,
-      "requires": {
-        "@babel/code-frame": "7.0.0-beta.44",
-        "@babel/generator": "7.0.0-beta.44",
-        "@babel/helper-function-name": "7.0.0-beta.44",
-        "@babel/helper-split-export-declaration": "7.0.0-beta.44",
-        "@babel/types": "7.0.0-beta.44",
-        "babylon": "7.0.0-beta.44",
-        "debug": "^3.1.0",
-        "globals": "^11.1.0",
-        "invariant": "^2.2.0",
-        "lodash": "^4.2.0"
-      },
-      "dependencies": {
-        "@babel/code-frame": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.0.0-beta.44.tgz",
-          "integrity": "sha512-cuAuTTIQ9RqcFRJ/Y8PvTh+paepNcaGxwQwjIDRWPXmzzyAeCO4KqS9ikMvq0MCbRk6GlYKwfzStrcP3/jSL8g==",
-          "dev": true,
-          "requires": {
-            "@babel/highlight": "7.0.0-beta.44"
-          }
-        },
-        "@babel/highlight": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.0.0-beta.44.tgz",
-          "integrity": "sha512-Il19yJvy7vMFm8AVAh6OZzaFoAd0hbkeMZiX3P5HGD+z7dyI7RzndHB0dg6Urh/VAFfHtpOIzDUSxmY6coyZWQ==",
-          "dev": true,
-          "requires": {
-            "chalk": "^2.0.0",
-            "esutils": "^2.0.2",
-            "js-tokens": "^3.0.0"
-          }
-        },
-        "babylon": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/babylon/-/babylon-7.0.0-beta.44.tgz",
-          "integrity": "sha512-5Hlm13BJVAioCHpImtFqNOF2H3ieTOHd0fmFGMxOJ9jgeFqeAwsv3u5P5cR7CSeFrkgHsT19DgFJkHV0/Mcd8g==",
-          "dev": true
-        }
-      }
-    },
-    "@babel/types": {
-      "version": "7.0.0-beta.44",
-      "resolved": "https://registry.npmjs.org/@babel/types/-/types-7.0.0-beta.44.tgz",
-      "integrity": "sha512-5eTV4WRmqbaFM3v9gHAIljEQJU4Ssc6fxL61JN+Oe2ga/BwyjzjamwkCVVAQjHGuAX8i0BWo42dshL8eO5KfLQ==",
-      "dev": true,
-      "requires": {
-        "esutils": "^2.0.2",
-        "lodash": "^4.2.0",
-        "to-fast-properties": "^2.0.0"
-      },
-      "dependencies": {
-        "to-fast-properties": {
-          "version": "2.0.0",
-          "resolved": "https://registry.npmjs.org/to-fast-properties/-/to-fast-properties-2.0.0.tgz",
-          "integrity": "sha1-3F5pjL0HkmW8c+A3doGk5Og/YW4=",
-          "dev": true
-        }
-      }
-    },
     "abab": {
       "version": "2.0.0",
       "resolved": "https://registry.npmjs.org/abab/-/abab-2.0.0.tgz",
@@ -517,58 +362,6 @@
         }
       }
     },
-    "babel-eslint": {
-      "version": "8.2.6",
-      "resolved": "https://registry.npmjs.org/babel-eslint/-/babel-eslint-8.2.6.tgz",
-      "integrity": "sha512-aCdHjhzcILdP8c9lej7hvXKvQieyRt20SF102SIGyY4cUIiw6UaAtK4j2o3dXX74jEmy0TJ0CEhv4fTIM3SzcA==",
-      "dev": true,
-      "requires": {
-        "@babel/code-frame": "7.0.0-beta.44",
-        "@babel/traverse": "7.0.0-beta.44",
-        "@babel/types": "7.0.0-beta.44",
-        "babylon": "7.0.0-beta.44",
-        "eslint-scope": "3.7.1",
-        "eslint-visitor-keys": "^1.0.0"
-      },
-      "dependencies": {
-        "@babel/code-frame": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/code-frame/-/code-frame-7.0.0-beta.44.tgz",
-          "integrity": "sha512-cuAuTTIQ9RqcFRJ/Y8PvTh+paepNcaGxwQwjIDRWPXmzzyAeCO4KqS9ikMvq0MCbRk6GlYKwfzStrcP3/jSL8g==",
-          "dev": true,
-          "requires": {
-            "@babel/highlight": "7.0.0-beta.44"
-          }
-        },
-        "@babel/highlight": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/@babel/highlight/-/highlight-7.0.0-beta.44.tgz",
-          "integrity": "sha512-Il19yJvy7vMFm8AVAh6OZzaFoAd0hbkeMZiX3P5HGD+z7dyI7RzndHB0dg6Urh/VAFfHtpOIzDUSxmY6coyZWQ==",
-          "dev": true,
-          "requires": {
-            "chalk": "^2.0.0",
-            "esutils": "^2.0.2",
-            "js-tokens": "^3.0.0"
-          }
-        },
-        "babylon": {
-          "version": "7.0.0-beta.44",
-          "resolved": "https://registry.npmjs.org/babylon/-/babylon-7.0.0-beta.44.tgz",
-          "integrity": "sha512-5Hlm13BJVAioCHpImtFqNOF2H3ieTOHd0fmFGMxOJ9jgeFqeAwsv3u5P5cR7CSeFrkgHsT19DgFJkHV0/Mcd8g==",
-          "dev": true
-        },
-        "eslint-scope": {
-          "version": "3.7.1",
-          "resolved": "https://registry.npmjs.org/eslint-scope/-/eslint-scope-3.7.1.tgz",
-          "integrity": "sha1-PWPD7f2gLgbgGkUq2IyqzHzctug=",
-          "dev": true,
-          "requires": {
-            "esrecurse": "^4.1.0",
-            "estraverse": "^4.1.1"
-          }
-        }
-      }
-    },
     "babel-generator": {
       "version": "6.26.1",
       "resolved": "https://registry.npmjs.org/babel-generator/-/babel-generator-6.26.1.tgz",
@@ -1018,9 +811,9 @@
       "dev": true
     },
     "circular-json": {
-      "version": "0.3.3",
-      "resolved": "https://registry.npmjs.org/circular-json/-/circular-json-0.3.3.tgz",
-      "integrity": "sha512-UZK3NBx2Mca+b5LsG7bY183pHWt5Y1xts4P3Pz7ENTwGVnJOUWbRb3ocjvX7hx9tq/yTAdclXm9sZ38gNuem4A==",
+      "version": "0.5.5",
+      "resolved": "https://registry.npmjs.org/circular-json/-/circular-json-0.5.5.tgz",
+      "integrity": "sha512-13YaR6kiz0kBNmIVM87Io8Hp7bWOo4r61vkEANy8iH9R9bc6avud/1FT0SBpqR1RpIQADOh/Q+yHZDA1iL6ysA==",
       "dev": true
     },
     "class-utils": {
@@ -2044,6 +1837,14 @@
         "del": "^2.0.2",
         "graceful-fs": "^4.1.2",
         "write": "^0.2.1"
+      },
+      "dependencies": {
+        "circular-json": {
+          "version": "0.3.3",
+          "resolved": "https://registry.npmjs.org/circular-json/-/circular-json-0.3.3.tgz",
+          "integrity": "sha512-UZK3NBx2Mca+b5LsG7bY183pHWt5Y1xts4P3Pz7ENTwGVnJOUWbRb3ocjvX7hx9tq/yTAdclXm9sZ38gNuem4A==",
+          "dev": true
+        }
       }
     },
     "for-in": {
diff --git a/package.json b/package.json
index a396785..dc9f66b 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "vilanova",
   "description": "JSON stringify/parse pluggable library with support for BigInt",
-  "version": "0.0.1",
+  "version": "0.1.0",
   "main": "lib/index.js",
   "keywords": [
     "JSON",
@@ -39,6 +39,7 @@
   "license": "MIT",
   "dependencies": {},
   "devDependencies": {
+    "circular-json": "^0.5.5",
     "eslint": "^4.10.0",
     "eslint-config-airbnb-base": "^12.1.0",
     "eslint-plugin-import": "^2.8.0",
diff --git a/test/vilanova.test.js b/test/vilanova.test.js
index da1a4b9..1298ceb 100644
--- a/test/vilanova.test.js
+++ b/test/vilanova.test.js
@@ -1,22 +1,30 @@
 const Vilanova = require('../lib');
+const CircularJSON = require('circular-json'); 
 
-function generateStep(i) {
+function generateStep(i, circular = false) {
   const obj = {
     id: i,
     name: `name ${i}`,
     bigValue: BigInt('1000000000000000000000000000000') + BigInt(`${i}`),
   };
-  const str = `{"id":${i},"name":"name ${i}","bigValue":"#BigInt:${obj.bigValue}"}`;
+  if (circular) {
+    obj.ref = obj;
+  }
+  const str = circular ? `{"id":${i},"name":"name ${i}","bigValue":"#bigint:${obj.bigValue}","ref":"~${i}"}`
+    : `{"id":${i},"name":"name ${i}","bigValue":"#bigint:${obj.bigValue}"}`;
   return { obj, str };
 }
 
-function generateTestcase(numElements) {
+function generateTestcase(numElements, circular = false) {
   if (!numElements) {
     return generateStep(1);
   }
   const result = { obj: [], str: '' };
   for (let i = 0; i < numElements; i += 1) {
-    const step = generateStep(i);
+    const step = generateStep(i, circular);
+    if (circular) {
+      step.obj.ref = step.obj;
+    }
     result.obj.push(step.obj);
     result.str = i > 0 ? `${result.str},${step.str}` : `[${step.str}`;
   }
@@ -28,7 +36,7 @@ describe('Vilanova', () => {
   describe('Stringify', () => {
     test('It should stringify a BigInt', () => {
       const input = BigInt('123456789012345678901234567890');
-      const expected = '"#BigInt:123456789012345678901234567890"';
+      const expected = '"#bigint:123456789012345678901234567890"';
       const actual = Vilanova.stringify(input);
       expect(actual).toEqual(expected);
     });
@@ -42,6 +50,11 @@ describe('Vilanova', () => {
       const actual = Vilanova.stringify(testcase.obj);
       expect(actual).toEqual(testcase.str);
     });
+    test('It should allow to pass a custom stringify function', () => {
+      const testcase = generateTestcase(100, true);
+      const actual = Vilanova.stringify(testcase.obj, CircularJSON.stringify);
+      expect(actual).toEqual(testcase.str);
+    });
   });
 
   describe('Get Token', () => {
@@ -64,20 +77,20 @@ describe('Vilanova', () => {
       expect(actual).toEqual(expected);
     });
     test('It should return the source if does not start with #', () => {
-      const input = 'BigInt:123456';
+      const input = 'bigint:123456';
       const expected = { type: undefined, value: input };
       const actual = Vilanova.getToken(input);
       expect(actual).toEqual(expected);
     });
     test('It should return the source if does not contains :', () => {
-      const input = '#BigInt.123456';
+      const input = '#bigint.123456';
       const expected = { type: undefined, value: input };
       const actual = Vilanova.getToken(input);
       expect(actual).toEqual(expected);
     });
     test('It should pop the type if the format is correct', () => {
-      const input = '#BigInt:123456';
-      const expected = { type: 'BigInt', value: '123456' };
+      const input = '#bigint:123456';
+      const expected = { type: 'bigint', value: '123456' };
       const actual = Vilanova.getToken(input);
       expect(actual).toEqual(expected);
     });
@@ -85,7 +98,7 @@ describe('Vilanova', () => {
 
   describe('Parse', () => {
     test('It should parse a BigInt', () => {
-      const input = '"#BigInt:123456789012345678901234567890"';
+      const input = '"#bigint:123456789012345678901234567890"';
       const expected = BigInt('123456789012345678901234567890');
       const actual = Vilanova.parse(input);
       expect(actual).toEqual(expected);
@@ -106,5 +119,11 @@ describe('Vilanova', () => {
       const actual = Vilanova.parse(testcase.str);
       expect(actual).toEqual(testcase.obj);
     });
+    test('It should allow to pass a custom parse function', () => {
+      const testcase = generateTestcase(100, true);
+      const actual = Vilanova.parse(testcase.str, CircularJSON.parse);
+      expect(actual).toEqual(testcase.obj);
+    });
   });
+
 });