diff --git a/src/strops.c b/src/strops.c
index 7670533..4d126e7 100644
--- a/src/strops.c
+++ b/src/strops.c
@@ -37,7 +37,25 @@ char* strops_to_uppercase(const char* string) {
     return result;
 }
 
+char* strops_insert_at_pos(const char* string, const char* string_to_insert, size_t pos) {
+    assert(pos <= strlen(string) && "pos needs to be inside string");
+    size_t string_length = strlen(string) + strlen(string_to_insert) + 1;
+    char *result = malloc(string_length);
+    memcpy(result, string, strlen(string));
+    size_t i, j;
+    /* Make space for string_to_insert */
+    for (i = string_length - 1; i > pos; i--) {
+        result[i] = result[i - strlen(string_to_insert)];
+    }
+    /* Insert string into empty space */
+    for (j = 0; j < strlen(string_to_insert); j++) {
+        result[pos + j] = string_to_insert[j];
+    }
+    return result;
+}
+
 char* strops_remove_at_pos(const char* string, size_t pos) {
+    assert(pos <= strlen(string) && "pos needs to be inside string");
     char *result = malloc(strlen(string));
     memcpy(result, string, strlen(string));
     result[pos] = 0;
@@ -50,7 +68,7 @@ char* strops_remove_at_pos(const char* string, size_t pos) {
 }
 
 char* strops_trim_right_whitespace(const char* string) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     while (strchr("\t\n\v\f\r ", result[strlen(result) - 1]) != NULL) {
         result = strops_remove_at_pos(result, strlen(result) - 1);
@@ -60,7 +78,7 @@ char* strops_trim_right_whitespace(const char* string) {
 }
 
 char* strops_trim_left_whitespace(const char* string) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     while (strchr("\t\n\v\f\r ", result[0]) != NULL) {
         result = strops_remove_at_pos(result, 0);
@@ -70,7 +88,7 @@ char* strops_trim_left_whitespace(const char* string) {
 }
 
 char* strops_trim_both_whitespace(const char* string) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     result = strops_trim_right_whitespace(result);
     result = strops_trim_left_whitespace(result);
@@ -78,7 +96,7 @@ char* strops_trim_both_whitespace(const char* string) {
 }
 
 char* strops_trim_right_chars(const char* string, const char* chars_to_remove) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     while (strchr(chars_to_remove, result[strlen(result) - 1]) != NULL) {
         result = strops_remove_at_pos(result, strlen(result) - 1);
@@ -88,7 +106,7 @@ char* strops_trim_right_chars(const char* string, const char* chars_to_remove) {
 }
 
 char* strops_trim_left_chars(const char* string, const char* chars_to_remove) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     while (strchr(chars_to_remove, result[0]) != NULL) {
         result = strops_remove_at_pos(result, 0);
@@ -98,7 +116,7 @@ char* strops_trim_left_chars(const char* string, const char* chars_to_remove) {
 }
 
 char* strops_trim_both_chars(const char* string, const char* chars_to_remove) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     result = strops_trim_right_chars(result, chars_to_remove);
     result = strops_trim_left_chars(result, chars_to_remove);
@@ -107,7 +125,7 @@ char* strops_trim_both_chars(const char* string, const char* chars_to_remove) {
 
 char* strops_trim_right_string(const char* string, const char* string_to_remove) {
     assert(strlen(string) >= strlen(string_to_remove) && "string_to_remove cannot be bigger than string");
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     
     size_t offset = strlen(result) - strlen(string_to_remove);
@@ -126,7 +144,7 @@ char* strops_trim_right_string(const char* string, const char* string_to_remove)
 
 char* strops_trim_left_string(const char* string, const char* string_to_remove) {
     assert(strlen(string) >= strlen(string_to_remove) && "string_to_remove cannot be bigger than string");
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
 
     char *tmp = malloc(strlen(string_to_remove) + 1);
@@ -145,7 +163,7 @@ char* strops_trim_left_string(const char* string, const char* string_to_remove)
 
 char* strops_trim_both_string(const char* string, const char* string_to_remove) {
     assert(strlen(string) >= strlen(string_to_remove) && "string_to_remove cannot be bigger than string");
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     result = strops_trim_right_string(result, string_to_remove);
     result = strops_trim_left_string(result, string_to_remove);
@@ -153,7 +171,7 @@ char* strops_trim_both_string(const char* string, const char* string_to_remove)
 }
 
 char* strops_remove_chars(const char* string, const char* chars_to_remove) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
 
     size_t i;
@@ -168,7 +186,7 @@ char* strops_remove_chars(const char* string, const char* chars_to_remove) {
 
 char* strops_remove_string(const char* string, const char* string_to_remove) {
     assert(strlen(string) >= strlen(string_to_remove) && "string_to_remove cannot be bigger than string");
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
 
     while (strstr(result, string_to_remove) != NULL) {
@@ -184,7 +202,7 @@ char* strops_remove_string(const char* string, const char* string_to_remove) {
 
 size_t strops_word_count(const char* string) {
     size_t word_count = 0;
-    char *tmp = malloc(strlen(string));
+    char *tmp = malloc(strlen(string) + 1);
     memcpy(tmp, string, strlen(string));
 
     size_t i = 0;
@@ -225,14 +243,17 @@ size_t strops_word_count(const char* string) {
 }
 
 char* strops_url_encode(const char* string) {
-    char *result = malloc(strlen(string) * 3); /* multiplied by 3, because example: ( => %28. Three times the chars */
+    /* multiplied by 3, because example: ( => %28. Three times the chars */
+    char *result = malloc(strlen(string) * 3 + 1);
     memcpy(result, string, strlen(string));
+    char *unsafe_chars = "";
+
     result = realloc(result, strlen(result));
     return result;
 }
 
 char* strops_url_decode(const char* string) {
-    char *result = malloc(strlen(string));
+    char *result = malloc(strlen(string) + 1);
     memcpy(result, string, strlen(string));
     result = realloc(result, strlen(result));
     return result;
diff --git a/src/strops.h b/src/strops.h
index 3929080..089d6a6 100644
--- a/src/strops.h
+++ b/src/strops.h
@@ -13,6 +13,7 @@
 char* strops_to_lowercase(const char* string);
 char* strops_to_uppercase(const char* string);
 
+char* strops_insert_at_pos(const char* string, const char* string_to_insert, size_t pos);
 char* strops_remove_at_pos(const char* string, size_t pos);
 
 char* strops_trim_right_whitespace(const char* string);
@@ -32,6 +33,7 @@ char* strops_remove_string(const char* string, const char* string_to_remove);
 
 size_t strops_word_count(const char* string);
 
+/* https://www.w3schools.com/tags/ref_urlencode.asp */
 char* strops_url_encode(const char* string);
 char* strops_url_decode(const char* string);
 
diff --git a/src/tests.c b/src/tests.c
index 89c3b6c..a388f66 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -39,6 +39,18 @@ int test_to_uppercase() {
     return 0;
 }
 
+int test_insert_at_pos() {
+    char* input = "Heo, World!";
+    char* expected = "Hello, World!";
+    char* result = strops_insert_at_pos(input, "ll", 2);
+    if (strcmp(result, expected) != 0) {
+        printf("test_insert_at_pos failed\n");
+        printf("Got = '%s'\nExpected = '%s'\n", result, expected);
+        return 1;
+    }
+    return 0;
+}
+
 int test_remove_at_pos() {
     char* input = "Hello";
     char* expected = "Hllo";
@@ -220,7 +232,7 @@ int test_url_decode() {
 }
 
 int main() {
-    int amount_of_tests = 17;
+    int amount_of_tests = 18;
     int amount_of_successful_tests = 0;
     int ret;
     
@@ -241,6 +253,11 @@ int main() {
         amount_of_successful_tests++;
     }
 
+    ret = test_insert_at_pos();
+    if (ret == 0) {
+        amount_of_successful_tests++;
+    }
+
     ret = test_remove_at_pos();
     if (ret == 0) {
         amount_of_successful_tests++;