diff --git a/Makefile b/Makefile
index b55e0c2..5cf2fc4 100644
--- a/Makefile
+++ b/Makefile
@@ -18,7 +18,6 @@ _SRC += ft_isalpha.c
 _SRC += ft_isascii.c
 _SRC += ft_isdigit.c
 _SRC += ft_isprint.c
-_SRC += ft_isspace.c
 _SRC += ft_memchr.c
 _SRC += ft_memcmp.c
 _SRC += ft_memcpy.c
@@ -40,10 +39,10 @@ _SRC += ft_toupper.c
 # _SRC += ft_putstr_fd.c
 
 # _SRC += ft_itoa.c
-# _SRC += ft_strtrim.c
+_SRC += ft_strtrim.c
 _SRC += ft_substr.c
-# _SRC += ft_strjoin.c
-# _SRC += ft_split.c
+_SRC += ft_strjoin.c
+_SRC += ft_split.c
 # _SRC += ft_striteri.c
 # _SRC += ft_strmapi.c
 
@@ -57,6 +56,9 @@ _SRC += ft_substr.c
 # _SRC += ft_lstnew.c
 # _SRC += ft_lstsize.c
 
+_SRC += ft_char_in_charset.c
+_SRC += ft_isspace.c
+
 unexport _DEPS
 _DEPS += libft.h
 
diff --git a/a.out b/a.out
deleted file mode 100755
index 5596abd..0000000
Binary files a/a.out and /dev/null differ
diff --git a/ft_atoi.c b/ft_atoi.c
index ea6e9a3..ef85d38 100644
--- a/ft_atoi.c
+++ b/ft_atoi.c
@@ -6,14 +6,14 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 17:28:18 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 17:28:18 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 19:58:10 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 int	ft_isspace(int c);
 int	ft_isdigit(int c);
 
-int	ft_atoi(const char *nptr)
+int	ft_atoi(char const *nptr)
 {
 	int	res;
 	int	sign;
diff --git a/ft_char_in_charset.c b/ft_char_in_charset.c
new file mode 100644
index 0000000..10e2cf5
--- /dev/null
+++ b/ft_char_in_charset.c
@@ -0,0 +1,19 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_char_in_charset.c                               :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: tischmid <timo42@proton.me>                +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2023/06/02 19:43:41 by tischmid          #+#    #+#             */
+/*   Updated: 2023/06/02 20:38:04 by tischmid         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+int	ft_char_in_charset(char c, char const *charset)
+{
+	while (*charset)
+		if (*charset++ == c)
+			return (1);
+	return (0);
+}
diff --git a/ft_memcmp.c b/ft_memcmp.c
index 9c5bd86..3afe2bc 100644
--- a/ft_memcmp.c
+++ b/ft_memcmp.c
@@ -6,13 +6,13 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 16:44:15 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 16:44:15 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:03:03 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 
-int	ft_memcmp(const void *s1, const void *s2, size_t n)
+int	ft_memcmp(void const *s1, void const *s2, size_t n)
 {
 	unsigned char	*us1;
 	unsigned char	*us2;
diff --git a/ft_memcpy.c b/ft_memcpy.c
index b1e1f66..f26e9b5 100644
--- a/ft_memcpy.c
+++ b/ft_memcpy.c
@@ -6,16 +6,16 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/11 13:28:20 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/11 13:28:21 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:01:50 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 
-void	*ft_memcpy(void *dest, const void *src, size_t n)
+void	*ft_memcpy(void *dest, void const *src, size_t n)
 {
 	char		*d;
-	const char	*s;
+	char const	*s;
 
 	if (!src && !dest)
 		return (0);
diff --git a/ft_memmove.c b/ft_memmove.c
index 372c400..682e2d9 100644
--- a/ft_memmove.c
+++ b/ft_memmove.c
@@ -6,17 +6,17 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/11 16:19:10 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/11 16:19:11 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:02:37 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stdlib.h>
 #include <stddef.h>
 
-void	*ft_memmove(void *dest, const void *src, size_t n)
+void	*ft_memmove(void *dest, void const *src, size_t n)
 {
 	char		*d;
-	const char	*s;
+	char const	*s;
 
 	if (!src && !dest)
 		return (0);
diff --git a/ft_split.c b/ft_split.c
index e69de29..a8b3c33 100644
--- a/ft_split.c
+++ b/ft_split.c
@@ -0,0 +1,70 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_split.c                                         :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: tischmid <timo42@proton.me>                +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2023/06/02 20:37:07 by tischmid          #+#    #+#             */
+/*   Updated: 2023/06/02 21:28:59 by tischmid         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "libft.h"
+#include <stdlib.h>
+
+static size_t	split_arr_len(char const *s, char c)
+{
+	size_t	len;
+
+	len = 0;
+	while (*s)
+	{
+		while (*s == c)
+			++s;
+		++len;
+		while (*s != c && *s)
+			++s;
+	}
+	return (len);
+}
+
+static int	save_strlcpy(char **arr, size_t len, char const *src, size_t size)
+{
+	if (!arr[len - 1])
+	{
+		while (len--)
+			free(arr[len]);
+		free(arr);
+		return (0);
+	}
+	ft_strlcpy(arr[len - 1], src, size);
+	return (1);
+}
+
+char	**ft_split(char const *s, char c)
+{
+	size_t		arr_len;
+	size_t		idx;
+	char		**arr;
+	char const	*start;
+
+	arr_len = split_arr_len(s, c);
+	arr = malloc(sizeof(char *) * (arr_len + 1));
+	if (!arr)
+		return (0);
+	idx = 0;
+	while (*s)
+	{
+		while (*s == c)
+			++s;
+		start = s;
+		while (*s != c && *s)
+			++s;
+		arr[idx] = malloc(sizeof(char) * (s - start + 1));
+		if (!save_strlcpy(arr, ++idx, start, s - start + 1))
+			return (0);
+	}
+	arr[idx] = (void *) 0;
+	return (arr);
+}
diff --git a/ft_strchr.c b/ft_strchr.c
index 13aec53..a0270fb 100644
--- a/ft_strchr.c
+++ b/ft_strchr.c
@@ -6,11 +6,11 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 16:20:31 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 16:20:33 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 19:58:22 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
-char	*ft_strchr(const char *s, int c)
+char	*ft_strchr(char const *s, int c)
 {
 	while (*s)
 		if (*s++ == (unsigned char) c)
diff --git a/ft_strdup.c b/ft_strdup.c
index 67f05db..29d3751 100644
--- a/ft_strdup.c
+++ b/ft_strdup.c
@@ -6,16 +6,14 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 19:12:24 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 19:15:06 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:01:24 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
+#include "libft.h"
 #include <stdlib.h>
 
-size_t	ft_strlen(const char *s);
-size_t	ft_strlcpy(char *dst, const char *src, size_t size);
-
-char	*ft_strdup(const char *s)
+char	*ft_strdup(char const *s)
 {
 	char	*s2;
 	size_t	len;
diff --git a/ft_strjoin.c b/ft_strjoin.c
index 973af94..4170a7f 100644
--- a/ft_strjoin.c
+++ b/ft_strjoin.c
@@ -6,22 +6,22 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/24 13:43:29 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/24 13:43:30 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 19:39:01 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include "libft.h"
 
-char	*ft_strjoin(char const *s1, char const s2)
+char	*ft_strjoin(char const *s1, char const *s2)
 {
 	size_t	total_len;
 	char	*joined_str;
 
 	total_len = ft_strlen(s1) + ft_strlen(s2);
-	joined_str = ft_calloc(sizeof(char) * (total_len + 1));
+	joined_str = ft_calloc(total_len + 1, sizeof(char));
 	if (!joined_str)
 		return (0);
-	ft_strlcpy(joined_str, s1, total_len);
-	ft_strlcat(joined_str, s2, total_len);
+	ft_strlcat(joined_str, s1, total_len + 1);
+	ft_strlcat(joined_str, s2, total_len + 1);
 	return (joined_str);
 }
diff --git a/ft_strlcat.c b/ft_strlcat.c
index 5be81cc..0746d67 100644
--- a/ft_strlcat.c
+++ b/ft_strlcat.c
@@ -6,42 +6,39 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/11 16:55:00 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/11 16:55:01 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:02:14 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 
-size_t	ft_strlcat(char *dst, const char *src, size_t size)
+size_t	ft_strlcat(char *dst, char const *src, size_t size)
 {
 	size_t	idx;
+	size_t	sidx;
 	size_t	slen;
 	size_t	dlen;
 
+	slen = 0;
+	while (src[slen])
+		++slen;
 	idx = 0;
 	while (dst[idx])
 		++idx;
 	dlen = idx;
 	if (dlen > size)
-		return (size);
-	slen = 0;
-	while (src[slen])
-		dst[idx++] = src[slen++];
+		return (slen + size);
+	sidx = 0;
+	size -= dlen;
+	while (size-- > 1 && src[sidx])
+		dst[idx++] = src[sidx++];
+	dst[idx] = 0;
 	return (dlen + slen);
 }
 
-// #include <bsd/string.h>
-// #include <stdio.h>
-// int main()
-// {
-//	 printf("%d", ft_strlcat());
-//	 printf("%d", ft_strlcat());
-//	 return (0);
-// }
-
 /*
 Alternative implementation
-size_t	ft_strlcat(char *dst, const char *src, size_t size)
+size_t	ft_strlcat(char *dst, char const *src, size_t size)
 {
 	size_t	dst_len;
 	size_t	src_len;
diff --git a/ft_strlcpy.c b/ft_strlcpy.c
index 693e972..89390f0 100644
--- a/ft_strlcpy.c
+++ b/ft_strlcpy.c
@@ -6,24 +6,24 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/11 16:55:00 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/11 16:55:01 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 19:58:55 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 
-size_t	ft_strlcpy(char *dst, const char *src, size_t size)
+size_t	ft_strlcpy(char *dst, char const *src, size_t size)
 {
 	char	*d;
 	size_t	len;
 
 	d = dst;
 	len = 0;
-	while (++len < size && *src)
-		*d++ = *src++;
+	while (len + 1 < size && src[len])
+		*d++ = src[len++];
 	if (size)
 		*d = 0;
-	while (*src && src++)
+	while (src[len])
 		len++;
-	return (len - 1);
+	return (len);
 }
diff --git a/ft_strlen.c b/ft_strlen.c
index 40f6019..c46a154 100644
--- a/ft_strlen.c
+++ b/ft_strlen.c
@@ -6,13 +6,13 @@
 /*   By: tischmid <timo42@proton.me>                +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/03 23:07:08 by tischmid          #+#    #+#             */
-/*   Updated: 2023/05/03 23:16:02 by tischmid         ###   ########.fr       */
+/*   Updated: 2023/06/02 20:02:05 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 
-size_t	ft_strlen(const char *s)
+size_t	ft_strlen(char const *s)
 {
 	size_t	length;
 
diff --git a/ft_strncmp.c b/ft_strncmp.c
index ecdcfea..353691f 100644
--- a/ft_strncmp.c
+++ b/ft_strncmp.c
@@ -6,14 +6,14 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 16:29:43 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 16:29:44 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 19:59:48 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #include <stddef.h>
 #include <stdio.h>
 
-int	ft_strncmp(const char *s1, const char *s2, size_t n)
+int	ft_strncmp(char const *s1, char const *s2, size_t n)
 {
 	unsigned char	*us1;
 	unsigned char	*us2;
diff --git a/ft_strnstr.c b/ft_strnstr.c
index 4d3b540..c9beb00 100644
--- a/ft_strnstr.c
+++ b/ft_strnstr.c
@@ -6,16 +6,13 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 17:05:27 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 17:05:28 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:00:04 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
-#include <stddef.h>
+#include "libft.h"
 
-size_t	ft_strlen(const char *s);
-int		ft_memcmp(const void *s1, const void *s2, size_t n);
-
-char	*ft_strnstr(const char *big, const char *little, size_t len)
+char	*ft_strnstr(char const *big, char const *little, size_t len)
 {
 	size_t	l_len;
 	size_t	b_len;
diff --git a/ft_strrchr.c b/ft_strrchr.c
index 836b795..c3c98c6 100644
--- a/ft_strrchr.c
+++ b/ft_strrchr.c
@@ -6,11 +6,11 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/22 16:24:42 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/22 16:24:42 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:00:15 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
-char	*ft_strrchr(const char *s, int c)
+char	*ft_strrchr(char const *s, int c)
 {
 	char	*last;
 
diff --git a/ft_strtrim.c b/ft_strtrim.c
index e69de29..c2967fd 100644
--- a/ft_strtrim.c
+++ b/ft_strtrim.c
@@ -0,0 +1,50 @@
+/* ************************************************************************** */
+/*                                                                            */
+/*                                                        :::      ::::::::   */
+/*   ft_strtrim.c                                       :+:      :+:    :+:   */
+/*                                                    +:+ +:+         +:+     */
+/*   By: tischmid <timo42@proton.me>                +#+  +:+       +#+        */
+/*                                                +#+#+#+#+#+   +#+           */
+/*   Created: 2023/06/02 19:38:21 by tischmid          #+#    #+#             */
+/*   Updated: 2023/06/02 20:38:50 by tischmid         ###   ########.fr       */
+/*                                                                            */
+/* ************************************************************************** */
+
+#include "libft.h"
+#include <stdlib.h>
+
+static size_t	len_after_trim(char const *s1, char const *set)
+{
+	size_t	idx;
+	size_t	start;
+	size_t	end;
+
+	idx = 0;
+	while (ft_char_in_charset(s1[idx], set))
+		++idx;
+	if (!s1[idx])
+		return (0);
+	start = idx;
+	while (s1[idx])
+		++idx;
+	--idx;
+	while (ft_char_in_charset(s1[idx], set))
+		--idx;
+	end = idx;
+	return (end - start + 1);
+}
+
+char	*ft_strtrim(char const *s1, char const *set)
+{
+	size_t	trimmed_len;
+	char	*trimmed_str;
+
+	trimmed_len = len_after_trim(s1, set);
+	trimmed_str = malloc(sizeof(char) * (trimmed_len + 1));
+	if (!trimmed_str)
+		return (0);
+	while (ft_char_in_charset(*s1, set))
+		++s1;
+	ft_strlcpy(trimmed_str, s1, trimmed_len + 1);
+	return (trimmed_str);
+}
diff --git a/ft_substr.c b/ft_substr.c
index 52339e5..b249a65 100644
--- a/ft_substr.c
+++ b/ft_substr.c
@@ -6,15 +6,13 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/24 13:23:00 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/24 13:23:01 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 20:01:07 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
+#include "libft.h"
 #include <stdlib.h>
 
-void	*ft_calloc(size_t nmemb, size_t size);
-size_t	ft_strlcpy(char *dst, const char *src, size_t size);
-
 char	*ft_substr(char const *s, unsigned int start, size_t len)
 {
 	unsigned int	idx;
diff --git a/libft.h b/libft.h
index 41676aa..8f462d7 100644
--- a/libft.h
+++ b/libft.h
@@ -6,16 +6,15 @@
 /*   By: tosuman <timo42@proton.me>                 +#+  +:+       +#+        */
 /*                                                +#+#+#+#+#+   +#+           */
 /*   Created: 2023/05/11 11:31:44 by tosuman           #+#    #+#             */
-/*   Updated: 2023/05/11 11:31:46 by tosuman          ###   ########.fr       */
+/*   Updated: 2023/06/02 21:25:33 by tischmid         ###   ########.fr       */
 /*                                                                            */
 /* ************************************************************************** */
 
 #ifndef LIBFT_H
 # define LIBFT_H
-
 # include <stddef.h>
 
-int		ft_atoi(const char *nptr);
+int		ft_atoi(char const *nptr);
 void	ft_bzero(void *s, size_t n);
 void	*ft_calloc(size_t nmemb, size_t size);
 int		ft_isalnum(int c);
@@ -24,22 +23,26 @@ int		ft_isascii(int c);
 int		ft_isdigit(int c);
 int		ft_isprint(int c);
 int		ft_isspace(int c);
-void	*ft_memchr(const void *s, int c, size_t n);
-int		ft_memcmp(const void *s1, const void *s2, size_t n);
-void	*ft_memcpy(void *dest, const void *src, size_t n);
-void	*ft_memmove(void *dest, const void *src, size_t n);
+void	*ft_memchr(void const *s, int c, size_t n);
+int		ft_memcmp(void const *s1, void const *s2, size_t n);
+void	*ft_memcpy(void *dest, void const *src, size_t n);
+void	*ft_memmove(void *dest, void const *src, size_t n);
 void	*ft_memset(void *s, int c, size_t n);
-char	*ft_strchr(const char *s, int c);
-char	*ft_strdup(const char *s);
-size_t	ft_strlcat(char *dst, const char *src, size_t size);
-size_t	ft_strlcpy(char *dst, const char *src, size_t size);
-size_t	ft_strlen(const char *s);
-int		ft_strncmp(const char *s1, const char *s2, size_t n);
-char	*ft_strnstr(const char *big, const char *little, size_t len);
-char	*ft_strrchr(const char *s, int c);
+char	*ft_strchr(char const *s, int c);
+char	*ft_strdup(char const *s);
+size_t	ft_strlcat(char *dst, char const *src, size_t size);
+size_t	ft_strlcpy(char *dst, char const *src, size_t size);
+size_t	ft_strlen(char const *s);
+int		ft_strncmp(char const *s1, char const *s2, size_t n);
+char	*ft_strnstr(char const *big, char const *little, size_t len);
+char	*ft_strrchr(char const *s, int c);
 int		ft_tolower(int c);
 int		ft_toupper(int c);
 char	*ft_substr(char const *s, unsigned int start, size_t len);
+char	*ft_strjoin(char const *s1, char const *s2);
+char	*ft_strtrim(char const *s1, char const *set);
+int		ft_char_in_charset(char c, char const *charset);
+char	**ft_split(char const *s, char c);
 
 typedef struct s_list
 {