diff --git a/in-memory-cache/__tests__/in-memory-cache.spec.js b/in-memory-cache/__tests__/in-memory-cache.spec.js
new file mode 100644
index 0000000..c0e1ba9
--- /dev/null
+++ b/in-memory-cache/__tests__/in-memory-cache.spec.js
@@ -0,0 +1,122 @@
+describe("In memory cache - challenge", () => {
+  it("should construct a cache with a given size", () => {
+    const cache = new InMemoryCache(10);
+    expect(cache).toBeDefined();
+    expect(cache.capacity).toBe(10);
+  });
+
+  it("should be able to set and get value", () => {
+    const cache = new InMemoryCache(10);
+    const data = { keyName: "key1", value: "value1" };
+    cache.set(data.keyName, data.value);
+    expect(cache.get(data.keyName)).toBe(data.value);
+  });
+
+  it("should throw an error when trying to set a value with a null key", () => {
+    const cache = new InMemoryCache(10);
+    const data = {keyName: null, value: "value1"};
+    expect(() => cache.set(data.keyName, data.value)).toThrowError("Key must be a non-null string");
+  });
+
+  it("should throw an error when trying to set a value with a null value", () => {
+    const cache = new InMemoryCache(10);
+    const data = {keyName: "key1", value: null};
+    expect(() => cache.set(key, data.value)).toThrowError("Value must be a non-null value");
+  });
+
+  it("should only take buffers as values", () => {
+    const cache = new InMemoryCache(10);
+    const data = { keyName: "key1", value: "value1" };
+    expect(() => cache.set(data.keyName, data.value)).toThrowError("Value must be a buffer");
+  });
+
+  it("should throw an error when trying to set a value with a key that is not a string", () => {
+    const cache = new InMemoryCache(10);
+    const data = {keyName: 1, value: "value1"};
+    expect(() => cache.set(data.keyName, data.value)).toThrowError("Key must be a non-null string");
+  });
+
+  it("should throw an error when trying to set a key that is undefined", () => {
+    const cache = new InMemoryCache(10);
+    const data = {keyName: undefined, value: "value1"};
+    expect(() => cache.set(data.keyName, data.value)).toThrowError("Key must be a non-null string");
+  });
+
+  it("should throw an error when trying to set a value that is undefined", () => {
+    const cache = new InMemoryCache(10);
+    const data = {keyName: "key1", value: undefined};
+    expect(() => cache.set(data.keyName, data.value)).toThrowError("Value must be a non-null value");
+  });
+
+  it("should be able to set and get multiple values", () => {
+    const cache = new InMemoryCache(10);
+    const data = [
+      { keyName: "key1", value: "value1" },
+      { keyName: "key2", value: "value2" },
+      { keyName: "key3", value: "value3" }
+    ];
+    data.forEach(d => cache.set(d.keyName, d.value));
+    data.forEach(d => expect(cache.get(d.keyName)).toBe(d.value));
+  });
+
+  it("should throw an error when trying to get a non-existing value", () => {
+    const cache = new InMemoryCache(10);
+    expect(() => cache.get("key1")).toThrowError("Key not found");
+  });
+
+  it("should throw an error when trying to set a value with a key that already exists", () => {
+    const cache = new InMemoryCache(10);
+    const data = { keyName: "key1", value: "value1", overwriteValue: "value2" };
+    cache.set(data.keyName, data.value);
+    expect(() => cache.set(data.keyName, data.overwriteValue)).toThrowError("Key already exists");
+  });
+
+  it("should remove the least recently used item when the cache bytes capacity is reached", () => {
+    const cache = new InMemoryCache(12);
+    const data = [
+      { keyName: "key1", value: "value1" },
+      { keyName: "key2", value: "value2" },
+      { keyName: "key3", value: "value3" }
+    ];
+    data.forEach(d => cache.set(d.keyName, d.value));
+    expect(cache.get(data[0].keyName)).toBeUndefined();
+    data.slice(1).forEach(d => expect(cache.get(d.keyName)).toBe(d.value));
+  });
+
+  it("should be able to remove a value based on its key", () => {
+    const cache = new InMemoryCache(10);
+    const data = [
+      { keyName: "key1", value: "value1" },
+      { keyName: "key2", value: "value2" },
+      { keyName: "key3", value: "value3" }
+    ];
+    data.forEach(d => cache.set(d.keyName, d.value));
+    cache.remove(data[0].keyName);
+    expect(cache.get(data[0].keyName)).toBeUndefined();
+    data.slice(1).forEach(d => expect(cache.get(d.keyName)).toBe(d.value));
+  });
+
+  it("should be able to remove all values", () => {
+    const cache = new InMemoryCache(10);
+    const data = [
+      { keyName: "key1", value: "value1" },
+      { keyName: "key2", value: "value2" },
+      { keyName: "key3", value: "value3" }
+    ];
+    data.forEach(d => cache.set(d.keyName, d.value));
+    cache.clear();
+    data.forEach(d => expect(cache.get(d.keyName)).toBeUndefined());
+  });
+
+  it("should be able to get current capacity", () => {
+    const cache = new InMemoryCache(10);
+    expect(cache.getCapacity()).toBe(10);
+  });
+
+  it("should be able to set new capacity", () => {
+    const cache = new InMemoryCache(10);
+    expect(cache.getCapacity()).toBe(10);
+    cache.setCapacity(12);
+    expect(cache.getCapacity()).toBe(12);
+  });
+});
diff --git a/in-memory-cache/cache.js b/in-memory-cache/cache.js
new file mode 100644
index 0000000..e0cc9f9
--- /dev/null
+++ b/in-memory-cache/cache.js
@@ -0,0 +1,18 @@
+/* In memory cache */
+
+function InMemoryCache(capacity) {};
+
+InMemoryCache.prototype.set = function (key, value) {}
+
+InMemoryCache.prototype.get = function (key) {};
+
+InMemoryCache.prototype.remove = function (key) {};
+
+InMemoryCache.prototype.clear = function () {}
+
+InMemoryCache.prototype.getCapacity = function () {}
+
+InMemoryCache.prototype.setCapacity = function (capacity) {};
+
+// Don't delete export
+module.exports = InMemoryCache;
diff --git a/in-memory-cache/my_cache_solution.js b/in-memory-cache/my_cache_solution.js
new file mode 100644
index 0000000..e0cc9f9
--- /dev/null
+++ b/in-memory-cache/my_cache_solution.js
@@ -0,0 +1,18 @@
+/* In memory cache */
+
+function InMemoryCache(capacity) {};
+
+InMemoryCache.prototype.set = function (key, value) {}
+
+InMemoryCache.prototype.get = function (key) {};
+
+InMemoryCache.prototype.remove = function (key) {};
+
+InMemoryCache.prototype.clear = function () {}
+
+InMemoryCache.prototype.getCapacity = function () {}
+
+InMemoryCache.prototype.setCapacity = function (capacity) {};
+
+// Don't delete export
+module.exports = InMemoryCache;