diff --git a/Makefile b/Makefile
index 4907163..d5a8348 100644
--- a/Makefile
+++ b/Makefile
@@ -8,6 +8,8 @@ SRC_DIR ?= src
 TEST_DIR ?= test
 INC_DIRS ?= include
 
+LIB := $(BUILD_DIR)/$(LIB_FILENAME)
+
 SRCS != find '$(SRC_DIR)' -iname '*.c'
 SRCS_H != find $(INC_DIRS) -iname '*.h'
 SRCS_TEST != find '$(TEST_DIR)' -iname '*.c'
@@ -25,7 +27,7 @@ INC_FLAGS := $(addprefix -I,$(INC_DIRS))
 #  object file is also recompiled if only a header is changed.
 # -MP: generate a dummy target for every header file (according to the  docs it
 #  prevents some errors when removing header files)
-CFLAGS ?= -MMD -MP -Wall -Werror -Wextra
+CFLAGS ?= -MMD -MP -Wall -Wextra -g
 CFLAGS += $(INC_FLAGS)
 
 .PHONY: all
@@ -34,8 +36,8 @@ all: vieter
 
 # =====COMPILATION=====
 .PHONY: vieter
-vieter: $(BUILD_DIR)/$(LIB_FILENAME)
-$(BUILD_DIR)/$(LIB_FILENAME): $(OBJS)
+vieter: $(LIB)
+$(LIB): $(OBJS)
 	ar -rcs $@ $(OBJS)
 
 $(BUILD_DIR)/$(SRC_DIR)/%.c.o: $(SRC_DIR)/%.c
@@ -48,13 +50,15 @@ $(BUILD_DIR)/$(SRC_DIR)/%.c.o: $(SRC_DIR)/%.c
 test: build-test
 	@ $(foreach bin,$(BINS_TEST),./$(bin);)
 
+test-mem: build-test
+	@ $(foreach bin,$(BINS_TEST),valgrind --tool=memcheck --error-exitcode=1 \
+		--track-origins=yes --leak-check=full ./$(bin);)
+
 .PHONY: build-test
 build-test: $(BINS_TEST)
 
-# For simplicity, we link every object file to each of the test files. This
-# might be changed later if this starts to become too slow.
-$(BINS_TEST): %: %.c.o $(OBJS)
-	$(CC) $^ -o $@
+$(BINS_TEST): %: %.c.o $(LIB)
+	$(CC) -L$(BUILD_DIR) -lvieter $^ -o $@
 
 # Each test includes the test directory, which contains the acutest header file
 $(BUILD_DIR)/$(TEST_DIR)/%.c.o: $(TEST_DIR)/%.c
diff --git a/include/vieter_tree.h b/include/vieter_tree.h
new file mode 100644
index 0000000..be381e5
--- /dev/null
+++ b/include/vieter_tree.h
@@ -0,0 +1,30 @@
+#ifndef VIETER_TREE
+#define VIETER_TREE
+
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct vieter_tree vieter_tree;
+
+typedef enum vieter_tree_error {
+  vieter_tree_ok = 0,
+  vieter_tree_already_present = 1,
+  vieter_tree_not_present = 2
+} vieter_tree_error;
+
+vieter_tree *vieter_tree_init();
+
+void vieter_tree_free(vieter_tree *tree);
+
+vieter_tree_error vieter_tree_insert(vieter_tree *tree, uint64_t key,
+                                     void *data);
+
+vieter_tree_error vieter_tree_search(void **out, vieter_tree *tree,
+                                     uint64_t key);
+
+vieter_tree_error vieter_tree_remove(void **out, vieter_tree *tree,
+                                     uint64_t key);
+
+uint64_t vieter_tree_size(vieter_tree *tree);
+
+#endif
diff --git a/src/tree/vieter_tree.c b/src/tree/vieter_tree.c
new file mode 100644
index 0000000..72360b0
--- /dev/null
+++ b/src/tree/vieter_tree.c
@@ -0,0 +1,100 @@
+#include "vieter_tree.h"
+#include "vieter_tree_node.h"
+
+struct vieter_tree {
+  uint64_t size;
+  vieter_tree_node *root;
+};
+
+vieter_tree *vieter_tree_init() { return calloc(1, sizeof(vieter_tree)); }
+
+uint64_t vieter_tree_size(vieter_tree *tree) { return tree->size; }
+
+vieter_tree_error vieter_tree_insert(vieter_tree *tree, uint64_t key,
+                                     void *data) {
+  if (tree->size == 0) {
+    tree->root = vieter_tree_node_init();
+    tree->root->key = key;
+    tree->root->data = data;
+    vieter_tree_node_set(tree->root, vieter_node_black);
+    tree->size = 1;
+
+    return vieter_tree_ok;
+  }
+
+  vieter_tree_error res = vieter_tree_node_insert(tree->root, key, data);
+
+  if (res != vieter_tree_ok) {
+    return res;
+  }
+
+  tree->size++;
+
+  return vieter_tree_ok;
+}
+
+vieter_tree_error vieter_tree_search(void **out, vieter_tree *tree,
+                                     uint64_t key) {
+  if (tree->size == 0) {
+    return vieter_tree_not_present;
+  }
+
+  return vieter_tree_node_search(out, tree->root, key);
+}
+
+vieter_tree_error vieter_tree_remove(void **out, vieter_tree *tree,
+                                     uint64_t key) {
+  if (tree->size == 0) {
+    return vieter_tree_not_present;
+  }
+
+  vieter_tree_error res = vieter_tree_node_remove(out, tree->root, key);
+
+  if (res != vieter_tree_ok) {
+    return res;
+  }
+
+  tree->size--;
+
+  return vieter_tree_ok;
+}
+
+void vieter_tree_free(vieter_tree *tree) {
+  if (tree->size == 0) {
+    goto end;
+  }
+
+  uint64_t capacity = 4;
+  uint64_t size = 1;
+  vieter_tree_node **stack = malloc(capacity * sizeof(vieter_tree_node *));
+  stack[0] = tree->root;
+
+  vieter_tree_node *node;
+
+  while (size > 0) {
+    node = stack[size - 1];
+    size--;
+
+    if (size + 2 > capacity) {
+      capacity *= 2;
+      stack = realloc(stack, capacity * sizeof(vieter_tree_node *));
+    }
+
+    if (node->left != NULL) {
+      stack[size] = node->left;
+      size++;
+    }
+
+    if (node->right != NULL) {
+      stack[size] = node->right;
+      size++;
+    }
+
+    vieter_tree_node_free(node);
+  }
+
+  free(stack);
+
+end:
+  free(tree);
+}
diff --git a/src/tree/vieter_tree_balancing.c b/src/tree/vieter_tree_balancing.c
new file mode 100644
index 0000000..56047a0
--- /dev/null
+++ b/src/tree/vieter_tree_balancing.c
@@ -0,0 +1,112 @@
+#include "vieter_tree_balancing.h"
+
+vieter_tree_node *vieter_tree_node_balance(vieter_tree_node *node) {
+  vieter_tree_node *parent = node->parent;
+  vieter_tree_node *grand_parent = parent->parent;
+  vieter_tree_node *root = grand_parent;
+  vieter_tree_node *left, *right;
+  vieter_tree_node *children[4];
+
+  uint64_t key_root = root->key;
+  void *data_root = root->data;
+
+  if (node->key < parent->key && parent->key < grand_parent->key) {
+    root->key = parent->key;
+    root->data = parent->data;
+
+    parent->key = key_root;
+    parent->data = data_root;
+
+    left = node;
+    right = parent;
+
+    children[0] = node->left;
+    children[1] = node->right;
+    children[2] = parent->right;
+    children[3] = grand_parent->right;
+  } else if (node->key < parent->key && parent->key > grand_parent->key) {
+    root->key = node->key;
+    root->data = node->data;
+
+    node->key = key_root;
+    node->data = data_root;
+
+    left = node;
+    right = parent;
+
+    children[0] = grand_parent->left;
+    children[1] = node->left;
+    children[2] = node->right;
+    children[3] = parent->right;
+  } else if (node->key > parent->key && parent->key < grand_parent->key) {
+    root->key = node->key;
+    root->data = node->data;
+
+    node->key = key_root;
+    node->data = data_root;
+
+    left = parent;
+    right = node;
+
+    children[0] = parent->left;
+    children[1] = node->left;
+    children[2] = node->right;
+    children[3] = grand_parent->right;
+  } else {
+    root->key = parent->key;
+    root->data = parent->data;
+
+    parent->key = key_root;
+    parent->data = data_root;
+
+    left = parent;
+    right = node;
+
+    children[0] = grand_parent->left;
+    children[1] = parent->left;
+    children[2] = node->left;
+    children[3] = node->right;
+  }
+
+  vieter_tree_node_set(left, vieter_node_black);
+  vieter_tree_node_set(right, vieter_node_black);
+  vieter_tree_node_unset(root, vieter_node_black);
+
+  left->left = children[0];
+  left->right = children[1];
+
+  if (children[0] != NULL)
+    children[0]->parent = left;
+
+  if (children[1] != NULL)
+    children[1]->parent = left;
+
+  right->left = children[2];
+  right->right = children[3];
+
+  if (children[2] != NULL)
+    children[2]->parent = right;
+
+  if (children[3] != NULL)
+    children[3]->parent = right;
+
+  root->left = left;
+  root->right = right;
+  left->parent = root;
+  right->parent = root;
+
+  return root;
+}
+
+void vieter_tree_node_balance_after_insert(vieter_tree_node *node) {
+  while (!vieter_tree_node_get(node, vieter_node_black) &&
+         node->parent != NULL &&
+         !vieter_tree_node_get(node->parent, vieter_node_black)) {
+    node = vieter_tree_node_balance(node);
+  }
+
+  // The root must always be black
+  if (node->parent == NULL) {
+    vieter_tree_node_set(node, vieter_node_black);
+  }
+}
diff --git a/src/tree/vieter_tree_balancing.h b/src/tree/vieter_tree_balancing.h
new file mode 100644
index 0000000..4492588
--- /dev/null
+++ b/src/tree/vieter_tree_balancing.h
@@ -0,0 +1,8 @@
+#ifndef VIETER_TREE_BALANCING
+#define VIETER_TREE_BALANCING
+
+#include "vieter_tree_node.h"
+
+void vieter_tree_node_balance_after_insert(vieter_tree_node *node);
+
+#endif
diff --git a/src/tree/vieter_tree_node.c b/src/tree/vieter_tree_node.c
new file mode 100644
index 0000000..40407a3
--- /dev/null
+++ b/src/tree/vieter_tree_node.c
@@ -0,0 +1,166 @@
+#include "vieter_tree_node.h"
+#include "vieter_tree_balancing.h"
+
+vieter_tree_node *vieter_tree_node_init() {
+  return calloc(1, sizeof(vieter_tree_node));
+}
+
+void vieter_tree_node_free(vieter_tree_node *node) { free(node); }
+
+void vieter_tree_node_add_child(vieter_tree_node *parent, uint64_t key,
+                                vieter_tree_node *child) {
+  if (parent == NULL) {
+    return;
+  }
+
+  if (key < parent->key) {
+    parent->left = child;
+  } else {
+    parent->right = child;
+  }
+
+  if (child != NULL) {
+    child->parent = parent;
+  }
+}
+
+void vieter_tree_node_replace_with_child(vieter_tree_node *to_replace,
+                                         vieter_tree_node *replacement) {
+  to_replace->key = replacement->key;
+  to_replace->data = replacement->data;
+  to_replace->left = replacement->left;
+  to_replace->right = replacement->right;
+
+  if (to_replace->left != NULL)
+    to_replace->left->parent = to_replace;
+
+  if (to_replace->right != NULL)
+    to_replace->right->parent = to_replace;
+}
+
+vieter_tree_error vieter_tree_node_insert(vieter_tree_node *root, uint64_t key,
+                                          void *data) {
+  vieter_tree_node *node = root;
+  vieter_tree_node *parent = root;
+
+  while (node != NULL) {
+    if (node->key == key) {
+      return vieter_tree_already_present;
+    }
+
+    parent = node;
+
+    if (key < parent->key) {
+      node = parent->left;
+    } else {
+      node = parent->right;
+    }
+  }
+
+  vieter_tree_node *new_node = vieter_tree_node_init();
+  new_node->key = key;
+  new_node->data = data;
+
+  vieter_tree_node_add_child(parent, key, new_node);
+  vieter_tree_node_balance_after_insert(new_node);
+
+  return vieter_tree_ok;
+}
+
+vieter_tree_error vieter_tree_node_search_node(vieter_tree_node **out,
+                                               vieter_tree_node *root,
+                                               uint64_t key) {
+  vieter_tree_node *node = root;
+
+  while (node != NULL) {
+    if (node->key == key) {
+      *out = node;
+
+      return vieter_tree_ok;
+    }
+
+    if (key < node->key) {
+      node = node->left;
+    } else {
+      node = node->right;
+    }
+  }
+
+  return vieter_tree_not_present;
+}
+
+vieter_tree_error vieter_tree_node_search(void **out, vieter_tree_node *root,
+                                          uint64_t key) {
+  vieter_tree_node *target;
+  vieter_tree_error res = vieter_tree_node_search_node(&target, root, key);
+
+  if (res != vieter_tree_ok) {
+    return res;
+  }
+
+  *out = target->data;
+
+  return vieter_tree_ok;
+}
+
+vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root,
+                                          uint64_t key) {
+  vieter_tree_node *target;
+  vieter_tree_error res = vieter_tree_node_search_node(&target, root, key);
+
+  if (res != vieter_tree_ok) {
+    return res;
+  }
+
+  *out = target->data;
+
+  if (target->left == NULL && target->right == NULL) {
+    vieter_tree_node_add_child(target->parent, target->key, NULL);
+
+    vieter_tree_node_free(target);
+  } else if ((target->left == NULL) ^ (target->right == NULL)) {
+    vieter_tree_node *child =
+        target->left != NULL ? target->left : target->right;
+
+    if (target->parent != NULL) {
+      vieter_tree_node_add_child(target->parent, child->key, child);
+      vieter_tree_node_free(target);
+    } else {
+      vieter_tree_node_replace_with_child(target, child);
+      vieter_tree_node_free(child);
+    }
+
+  } else {
+    vieter_tree_node *replacement = target->right;
+
+    while (replacement->left != NULL) {
+      replacement = replacement->left;
+    }
+
+    // We use replacement->key here because the right child can be NULL, so
+    // reading its key isn't safe. Using replacement->key however, the child
+    // will still get placed into the right location because of how binary
+    // trees work.
+    vieter_tree_node_add_child(replacement->parent, replacement->key,
+                               replacement->right);
+
+    target->key = replacement->key;
+    target->data = replacement->data;
+
+    vieter_tree_node_free(replacement);
+  }
+
+  return vieter_tree_ok;
+}
+
+void vieter_tree_node_set(vieter_tree_node *node, vieter_node_flag flag) {
+  node->flags |= flag;
+}
+
+void vieter_tree_node_unset(vieter_tree_node *node, vieter_node_flag flag) {
+  node->flags &= ~flag;
+}
+
+bool vieter_tree_node_get(vieter_tree_node *node, vieter_node_flag flag) {
+  return (node->flags & flag) != 0;
+}
diff --git a/src/tree/vieter_tree_node.h b/src/tree/vieter_tree_node.h
new file mode 100644
index 0000000..522ee59
--- /dev/null
+++ b/src/tree/vieter_tree_node.h
@@ -0,0 +1,43 @@
+#ifndef VIETER_TREE_NODE
+#define VIETER_TREE_NODE
+
+#include "vieter_tree.h"
+#include <stdint.h>
+#include <stdbool.h>
+
+#define VIETER_NODE_BLACK ((uint8_t)1)
+
+typedef enum vieter_node_flag {
+    vieter_node_black = ((uint8_t)1) << 0
+} vieter_node_flag;
+
+typedef struct vieter_tree_node {
+    uint64_t key;
+    void *data;
+    struct vieter_tree_node *parent;
+    struct vieter_tree_node *left;
+    struct vieter_tree_node *right;
+    uint8_t flags;
+} vieter_tree_node;
+
+vieter_tree_node *vieter_tree_node_init();
+
+void vieter_tree_node_free(vieter_tree_node *node);
+
+vieter_tree_error vieter_tree_node_insert(vieter_tree_node *root, uint64_t key, void *data);
+
+vieter_tree_error vieter_tree_node_search_node(vieter_tree_node **out, vieter_tree_node *root, uint64_t key);
+vieter_tree_error vieter_tree_node_search(void **out, vieter_tree_node *root, uint64_t key);
+
+vieter_tree_error vieter_tree_node_remove(void **out, vieter_tree_node *root, uint64_t key);
+
+void vieter_tree_node_replace(vieter_tree_node *to_replace, vieter_tree_node *replacement);
+
+void vieter_tree_node_set(vieter_tree_node *node, vieter_node_flag flag);
+void vieter_tree_node_unset(vieter_tree_node *node, vieter_node_flag flag);
+bool vieter_tree_node_get(vieter_tree_node *node, vieter_node_flag flag);
+
+void vieter_tree_node_add_child(vieter_tree_node *parent, uint64_t key,
+                                vieter_tree_node *child);
+
+#endif
diff --git a/test/tree/test_binary_tree.c b/test/tree/test_binary_tree.c
new file mode 100644
index 0000000..aa7fc0f
--- /dev/null
+++ b/test/tree/test_binary_tree.c
@@ -0,0 +1,58 @@
+#include "acutest.h"
+#include "vieter_tree.h"
+
+#define TEST_SIZE(tree, size) \
+    TEST_CHECK(vieter_tree_size(tree) == size); \
+    TEST_MSG("Size: %zu", vieter_tree_size(tree))
+
+void test_init() {
+    vieter_tree *tree = vieter_tree_init();
+    TEST_CHECK(tree != NULL);
+    TEST_SIZE(tree, 0);
+    vieter_tree_free(tree);
+}
+
+void test_insert() {
+    vieter_tree *tree = vieter_tree_init();
+
+    for (uint64_t i = 0; i < 250; i++) {
+        TEST_CHECK(vieter_tree_insert(tree, i, NULL) == vieter_tree_ok);
+        TEST_SIZE(tree, i + 1);
+    }
+
+    void *out;
+
+    for (uint64_t i = 0; i < 250; i++) {
+        TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_ok);
+        TEST_CHECK(vieter_tree_insert(tree, i, NULL) == vieter_tree_already_present);
+        TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_ok);
+    }
+
+    vieter_tree_free(tree);
+}
+
+void test_remove() {
+    vieter_tree *tree = vieter_tree_init();
+
+    for (uint64_t i = 0; i < 250; i++) {
+        TEST_CHECK(vieter_tree_insert(tree, i, NULL) == vieter_tree_ok);
+    }
+
+    void *out;
+
+    for (uint64_t i = 0; i < 250; i++) {
+        TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_ok);
+        TEST_CHECK(vieter_tree_remove(&out, tree, i) == vieter_tree_ok);
+        TEST_CHECK(vieter_tree_search(&out, tree, i) == vieter_tree_not_present);
+        TEST_SIZE(tree, 250 - i - 1);
+    }
+
+    vieter_tree_free(tree);
+}
+
+TEST_LIST = {
+    {"test_init", test_init},
+    {"test_insert", test_insert},
+    {"test_remove", test_remove},
+    {NULL, NULL}
+};