diff --git a/another_test.txt b/another_test.txt
new file mode 100644
index 0000000..7410249
--- /dev/null
+++ b/another_test.txt
@@ -0,0 +1 @@
+This is another test file for the diff viewer
diff --git a/builtins.c b/builtins.c
index 77899d3..399a877 100644
--- a/builtins.c
+++ b/builtins.c
@@ -5,6 +5,7 @@
 
 #include "builtins.h"
 #include "common.h"
+#include "diff_viewer.h"
 #include "filters.h"
 #include "fzf_native.h"
 #include "git_integration.h"
@@ -1113,7 +1114,7 @@ int lsh_gg(char **args) {
   } else if (strcmp(args[1], "l") == 0) {
     system("git log --oneline -10");
   } else if (strcmp(args[1], "d") == 0) {
-    system("git diff");
+    run_diff_viewer();
   } else if (strcmp(args[1], "b") == 0) {
     system("git branch");
   } else if (strcmp(args[1], "ch") == 0) {
diff --git a/builtins.o b/builtins.o
index 65ec758..b9a76ae 100644
Binary files a/builtins.o and b/builtins.o differ
diff --git a/diff_viewer.c b/diff_viewer.c
new file mode 100644
index 0000000..da16c32
--- /dev/null
+++ b/diff_viewer.c
@@ -0,0 +1,496 @@
+/**
+ * diff_viewer.c
+ * Interactive diff viewer implementation
+ */
+
+#include "diff_viewer.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <ctype.h>
+
+/**
+ * Initialize the diff viewer
+ */
+int init_diff_viewer(DiffViewer *viewer) {
+    if (!viewer) return 0;
+    
+    memset(viewer, 0, sizeof(DiffViewer));
+    viewer->selected_file = 0;
+    viewer->diff_scroll_offset = 0;
+    viewer->current_mode = MODE_FILE_LIST; // Start in file list mode
+    
+    get_terminal_size(&viewer->terminal_width, &viewer->terminal_height);
+    viewer->file_panel_width = viewer->terminal_width * 0.3; // 30% of screen width
+    
+    return 1;
+}
+
+/**
+ * Get terminal size
+ */
+void get_terminal_size(int *width, int *height) {
+    struct winsize w;
+    ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
+    *width = w.ws_col;
+    *height = w.ws_row;
+}
+
+/**
+ * Get list of changed files from git
+ */
+int get_changed_files(DiffViewer *viewer) {
+    if (!viewer) return 0;
+    
+    FILE *fp = popen("git status --porcelain 2>/dev/null", "r");
+    if (!fp) return 0;
+    
+    viewer->file_count = 0;
+    char line[512];
+    
+    while (fgets(line, sizeof(line), fp) != NULL && viewer->file_count < MAX_FILES) {
+        // Remove newline
+        char *newline = strchr(line, '\n');
+        if (newline) *newline = '\0';
+        
+        if (strlen(line) < 3) continue;
+        
+        // Parse git status format: "XY filename"
+        char status = line[0];
+        if (status == ' ') status = line[1]; // Check second column if first is space
+        
+        // Skip the status characters and space
+        char *filename = line + 3;
+        
+        // Store file info
+        viewer->files[viewer->file_count].status = status;
+        strncpy(viewer->files[viewer->file_count].filename, filename, MAX_FILENAME_LEN - 1);
+        viewer->files[viewer->file_count].filename[MAX_FILENAME_LEN - 1] = '\0';
+        
+        viewer->file_count++;
+    }
+    
+    pclose(fp);
+    return viewer->file_count;
+}
+
+/**
+ * Check if a file is a new untracked file
+ */
+int is_new_file(const char *filename) {
+    char cmd[1024];
+    snprintf(cmd, sizeof(cmd), "git ls-files --error-unmatch \"%s\" 2>/dev/null", filename);
+    
+    FILE *fp = popen(cmd, "r");
+    if (!fp) return 1; // Assume new if we can't check
+    
+    char output[256];
+    int is_tracked = (fgets(output, sizeof(output), fp) != NULL);
+    pclose(fp);
+    
+    return !is_tracked; // Return 1 if not tracked (new file)
+}
+
+/**
+ * Load content of a new file and show all lines as additions
+ */
+int load_new_file_content(DiffViewer *viewer, const char *filename) {
+    if (!viewer || !filename) return 0;
+    
+    FILE *fp = fopen(filename, "r");
+    if (!fp) return 0;
+    
+    viewer->diff_line_count = 0;
+    viewer->diff_scroll_offset = 0;
+    
+    // Add header line
+    DiffLine *header = &viewer->diff_lines[viewer->diff_line_count++];
+    snprintf(header->line, sizeof(header->line), "@@ New file: %s @@", filename);
+    header->type = '@';
+    header->line_number_old = 0;
+    header->line_number_new = 0;
+    
+    char line[1024];
+    int line_number = 1;
+    
+    while (fgets(line, sizeof(line), fp) != NULL && viewer->diff_line_count < MAX_DIFF_LINES) {
+        // Remove newline
+        char *newline_pos = strchr(line, '\n');
+        if (newline_pos) *newline_pos = '\0';
+        
+        DiffLine *diff_line = &viewer->diff_lines[viewer->diff_line_count];
+        
+        // Format as addition
+        snprintf(diff_line->line, sizeof(diff_line->line), "+%s", line);
+        diff_line->type = '+';
+        diff_line->line_number_old = 0;
+        diff_line->line_number_new = line_number++;
+        
+        viewer->diff_line_count++;
+    }
+    
+    fclose(fp);
+    return viewer->diff_line_count;
+}
+
+/**
+ * Load diff for a specific file
+ */
+int load_file_diff(DiffViewer *viewer, const char *filename) {
+    if (!viewer || !filename) return 0;
+    
+    // Check if this is a new untracked file
+    if (is_new_file(filename)) {
+        return load_new_file_content(viewer, filename);
+    }
+    
+    char cmd[1024];
+    snprintf(cmd, sizeof(cmd), "git diff HEAD -- \"%s\" 2>/dev/null", filename);
+    
+    FILE *fp = popen(cmd, "r");
+    if (!fp) return 0;
+    
+    viewer->diff_line_count = 0;
+    viewer->diff_scroll_offset = 0;
+    
+    char line[1024];
+    int old_line = 0, new_line = 0;
+    
+    while (fgets(line, sizeof(line), fp) != NULL && viewer->diff_line_count < MAX_DIFF_LINES) {
+        // Remove newline
+        char *newline_pos = strchr(line, '\n');
+        if (newline_pos) *newline_pos = '\0';
+        
+        DiffLine *diff_line = &viewer->diff_lines[viewer->diff_line_count];
+        
+        // Parse diff line
+        if (line[0] == '@' && line[1] == '@') {
+            // Hunk header: @@-old_start,old_count +new_start,new_count@@
+            sscanf(line, "@@-%d,%*d +%d,%*d@@", &old_line, &new_line);
+            old_line--; // Will be incremented before use
+            new_line--;
+            
+            strncpy(diff_line->line, line, sizeof(diff_line->line) - 1);
+            diff_line->line[sizeof(diff_line->line) - 1] = '\0';
+            diff_line->type = '@';
+            diff_line->line_number_old = old_line;
+            diff_line->line_number_new = new_line;
+        } else if (line[0] == '+') {
+            new_line++;
+            strncpy(diff_line->line, line, sizeof(diff_line->line) - 1);
+            diff_line->line[sizeof(diff_line->line) - 1] = '\0';
+            diff_line->type = '+';
+            diff_line->line_number_old = old_line;
+            diff_line->line_number_new = new_line;
+        } else if (line[0] == '-') {
+            old_line++;
+            strncpy(diff_line->line, line, sizeof(diff_line->line) - 1);
+            diff_line->line[sizeof(diff_line->line) - 1] = '\0';
+            diff_line->type = '-';
+            diff_line->line_number_old = old_line;
+            diff_line->line_number_new = new_line;
+        } else if (line[0] == ' ') {
+            old_line++;
+            new_line++;
+            strncpy(diff_line->line, line, sizeof(diff_line->line) - 1);
+            diff_line->line[sizeof(diff_line->line) - 1] = '\0';
+            diff_line->type = ' ';
+            diff_line->line_number_old = old_line;
+            diff_line->line_number_new = new_line;
+        } else {
+            // Skip other lines (file headers, etc.)
+            continue;
+        }
+        
+        viewer->diff_line_count++;
+    }
+    
+    pclose(fp);
+    
+    // If no diff content but file exists, it might be a new file added to git
+    if (viewer->diff_line_count == 0) {
+        return load_new_file_content(viewer, filename);
+    }
+    
+    return viewer->diff_line_count;
+}
+
+/**
+ * Render the diff viewer interface
+ */
+void render_diff_viewer(DiffViewer *viewer) {
+    if (!viewer) return;
+    
+    // Clear screen
+    printf("\033[2J\033[H");
+    
+    // Title bar
+    printf(ANSI_COLOR_CYAN "Git Diff Viewer" ANSI_COLOR_RESET);
+    if (viewer->current_mode == MODE_FILE_LIST) {
+        printf(" - Use ↑/↓ to navigate files, Enter to view, q to quit\n");
+    } else {
+        printf(" - Use ↑/↓ to scroll, ESC to return to file list, q to quit\n");
+    }
+    printf("─%.0*s\n", viewer->terminal_width - 1, "────────────────────────────────────────────────────────────────────────────────");
+    
+    int start_row = 2;
+    int available_height = viewer->terminal_height - start_row - 1;
+    
+    // Render file list (left panel)
+    for (int i = 0; i < available_height && i < viewer->file_count; i++) {
+        printf("\033[%d;1H", start_row + i + 1); // Position cursor
+        
+        if (i == viewer->selected_file) {
+            if (viewer->current_mode == MODE_FILE_LIST) {
+                printf(ANSI_COLOR_CYAN "► " ANSI_COLOR_RESET);
+            } else {
+                printf(ANSI_COLOR_GREEN "► " ANSI_COLOR_RESET);
+            }
+        } else {
+            printf("  ");
+        }
+        
+        // Status indicator
+        char status = viewer->files[i].status;
+        if (status == 'M') {
+            printf(ANSI_COLOR_YELLOW "M" ANSI_COLOR_RESET);
+        } else if (status == 'A') {
+            printf(ANSI_COLOR_GREEN "A" ANSI_COLOR_RESET);
+        } else if (status == 'D') {
+            printf(ANSI_COLOR_RED "D" ANSI_COLOR_RESET);
+        } else {
+            printf("%c", status);
+        }
+        
+        printf(" ");
+        
+        // Filename (truncated to fit panel)
+        char truncated_name[256];
+        int max_name_len = viewer->file_panel_width - 6;
+        if ((int)strlen(viewer->files[i].filename) > max_name_len) {
+            strncpy(truncated_name, viewer->files[i].filename, max_name_len - 3);
+            truncated_name[max_name_len - 3] = '\0';
+            strcat(truncated_name, "...");
+        } else {
+            strcpy(truncated_name, viewer->files[i].filename);
+        }
+        
+        printf("%-*s", max_name_len, truncated_name);
+        
+        // Vertical separator
+        printf("│");
+    }
+    
+    // Render diff content (right panel)
+    if (viewer->current_mode == MODE_FILE_CONTENT && 
+        viewer->file_count > 0 && viewer->selected_file < viewer->file_count) {
+        int diff_panel_start = viewer->file_panel_width + 1;
+        int diff_panel_width = viewer->terminal_width - diff_panel_start;
+        
+        for (int i = 0; i < available_height && 
+             (i + viewer->diff_scroll_offset) < viewer->diff_line_count; i++) {
+            
+            int line_idx = i + viewer->diff_scroll_offset;
+            DiffLine *line = &viewer->diff_lines[line_idx];
+            
+            printf("\033[%d;%dH", start_row + i + 1, diff_panel_start + 1);
+            
+            // Color code based on line type
+            if (line->type == '+') {
+                printf(ANSI_COLOR_GREEN);
+            } else if (line->type == '-') {
+                printf(ANSI_COLOR_RED);
+            } else if (line->type == '@') {
+                printf(ANSI_COLOR_CYAN);
+            }
+            
+            // Truncate line to fit panel
+            char display_line[1024];
+            int max_len = diff_panel_width - 1;
+            if ((int)strlen(line->line) > max_len) {
+                strncpy(display_line, line->line, max_len - 3);
+                display_line[max_len - 3] = '\0';
+                strcat(display_line, "...");
+            } else {
+                strcpy(display_line, line->line);
+            }
+            
+            printf("%-*s", max_len, display_line);
+            printf(ANSI_COLOR_RESET);
+        }
+    } else if (viewer->current_mode == MODE_FILE_LIST) {
+        // Show help text in the right panel when in file list mode
+        int diff_panel_start = viewer->file_panel_width + 1;
+        printf("\033[%d;%dH", start_row + 2, diff_panel_start + 3);
+        printf(ANSI_COLOR_YELLOW "Select a file and press Enter to view its diff" ANSI_COLOR_RESET);
+    }
+    
+    // Status line at bottom
+    printf("\033[%d;1H", viewer->terminal_height);
+    if (viewer->file_count > 0) {
+        if (viewer->current_mode == MODE_FILE_LIST) {
+            printf("File %d/%d: %s [File List Mode]", 
+                   viewer->selected_file + 1, 
+                   viewer->file_count,
+                   viewer->files[viewer->selected_file].filename);
+        } else {
+            printf("File %d/%d: %s [Content Mode - Line %d/%d]", 
+                   viewer->selected_file + 1, 
+                   viewer->file_count,
+                   viewer->files[viewer->selected_file].filename,
+                   viewer->diff_scroll_offset + 1,
+                   viewer->diff_line_count > 0 ? viewer->diff_line_count : 1);
+        }
+    } else {
+        printf("No changed files found");
+    }
+    
+    fflush(stdout);
+}
+
+/**
+ * Handle keyboard input for navigation
+ */
+int handle_diff_input(DiffViewer *viewer, char key) {
+    if (!viewer) return 0;
+    
+    int available_height = viewer->terminal_height - 3;
+    
+    switch (key) {
+        case 'q':
+        case 'Q':
+            return 0; // Exit
+            
+        case 27: // ESC
+            if (viewer->current_mode == MODE_FILE_CONTENT) {
+                viewer->current_mode = MODE_FILE_LIST;
+            } else {
+                return 0; // Exit if already in file list mode
+            }
+            break;
+            
+        case 'k':
+        case 65: // Up arrow
+            if (viewer->current_mode == MODE_FILE_LIST) {
+                // Navigate file list
+                if (viewer->selected_file > 0) {
+                    viewer->selected_file--;
+                }
+            } else {
+                // Scroll diff content up
+                if (viewer->diff_scroll_offset > 0) {
+                    viewer->diff_scroll_offset--;
+                }
+            }
+            break;
+            
+        case 'j':
+        case 66: // Down arrow
+            if (viewer->current_mode == MODE_FILE_LIST) {
+                // Navigate file list
+                if (viewer->selected_file < viewer->file_count - 1) {
+                    viewer->selected_file++;
+                }
+            } else {
+                // Scroll diff content down
+                if (viewer->diff_line_count > available_height && 
+                    viewer->diff_scroll_offset < viewer->diff_line_count - available_height) {
+                    viewer->diff_scroll_offset++;
+                }
+            }
+            break;
+            
+        case '\n':
+        case '\r':
+            if (viewer->current_mode == MODE_FILE_LIST && viewer->file_count > 0) {
+                // Enter file content mode and load diff
+                viewer->current_mode = MODE_FILE_CONTENT;
+                viewer->diff_scroll_offset = 0; // Reset scroll position
+                load_file_diff(viewer, viewer->files[viewer->selected_file].filename);
+            }
+            break;
+    }
+    
+    return 1; // Continue
+}
+
+/**
+ * Set terminal to raw mode for interactive input
+ */
+void set_raw_mode(struct termios *orig_termios) {
+    tcgetattr(STDIN_FILENO, orig_termios);
+    
+    struct termios raw = *orig_termios;
+    raw.c_lflag &= ~(ICANON | ECHO);
+    raw.c_cc[VTIME] = 0;
+    raw.c_cc[VMIN] = 1;
+    
+    tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw);
+}
+
+/**
+ * Restore terminal to original mode
+ */
+void restore_terminal_mode(struct termios *orig_termios) {
+    tcsetattr(STDIN_FILENO, TCSAFLUSH, orig_termios);
+}
+
+/**
+ * Run the interactive diff viewer
+ */
+int run_diff_viewer(void) {
+    DiffViewer viewer;
+    struct termios orig_termios;
+    
+    if (!init_diff_viewer(&viewer)) {
+        printf("Failed to initialize diff viewer\n");
+        return 1;
+    }
+    
+    if (get_changed_files(&viewer) == 0) {
+        printf("No changed files found\n");
+        return 1;
+    }
+    
+    // Don't load initial file diff - start in file list mode
+    
+    set_raw_mode(&orig_termios);
+    
+    int running = 1;
+    while (running) {
+        render_diff_viewer(&viewer);
+        
+        char c = getchar();
+        
+        // Handle escape sequences for arrow keys
+        if (c == 27) {
+            char seq[3];
+            if (read(STDIN_FILENO, &seq[0], 1) == 1 && seq[0] == '[') {
+                if (read(STDIN_FILENO, &seq[1], 1) == 1) {
+                    running = handle_diff_input(&viewer, seq[1]);
+                }
+            } else {
+                running = handle_diff_input(&viewer, c);
+            }
+        } else {
+            running = handle_diff_input(&viewer, c);
+        }
+    }
+    
+    restore_terminal_mode(&orig_termios);
+    printf("\033[2J\033[H"); // Clear screen
+    
+    cleanup_diff_viewer(&viewer);
+    return 0;
+}
+
+/**
+ * Clean up diff viewer resources
+ */
+void cleanup_diff_viewer(DiffViewer *viewer) {
+    // Nothing to clean up for now, but good to have for future expansion
+    (void)viewer;
+}
\ No newline at end of file
diff --git a/diff_viewer.h b/diff_viewer.h
new file mode 100644
index 0000000..a054834
--- /dev/null
+++ b/diff_viewer.h
@@ -0,0 +1,106 @@
+/**
+ * diff_viewer.h
+ * Interactive diff viewer for git changes
+ */
+
+#ifndef DIFF_VIEWER_H
+#define DIFF_VIEWER_H
+
+#include "common.h"
+#include <termios.h>
+
+#define MAX_FILES 100
+#define MAX_FILENAME_LEN 256
+#define MAX_DIFF_LINES 1000
+
+typedef struct {
+    char filename[MAX_FILENAME_LEN];
+    char status; // 'M' = modified, 'A' = added, 'D' = deleted
+} ChangedFile;
+
+typedef struct {
+    char line[512];
+    char type; // '+' = addition, '-' = deletion, ' ' = context
+    int line_number_old;
+    int line_number_new;
+} DiffLine;
+
+typedef enum {
+    MODE_FILE_LIST,
+    MODE_FILE_CONTENT
+} ViewMode;
+
+typedef struct {
+    ChangedFile files[MAX_FILES];
+    int file_count;
+    int selected_file;
+    DiffLine diff_lines[MAX_DIFF_LINES];
+    int diff_line_count;
+    int diff_scroll_offset;
+    int terminal_width;
+    int terminal_height;
+    int file_panel_width;
+    ViewMode current_mode;
+} DiffViewer;
+
+/**
+ * Initialize the diff viewer
+ */
+int init_diff_viewer(DiffViewer *viewer);
+
+/**
+ * Get list of changed files from git
+ */
+int get_changed_files(DiffViewer *viewer);
+
+/**
+ * Check if a file is a new untracked file
+ */
+int is_new_file(const char *filename);
+
+/**
+ * Load content of a new file and show all lines as additions
+ */
+int load_new_file_content(DiffViewer *viewer, const char *filename);
+
+/**
+ * Load diff for a specific file
+ */
+int load_file_diff(DiffViewer *viewer, const char *filename);
+
+/**
+ * Render the diff viewer interface
+ */
+void render_diff_viewer(DiffViewer *viewer);
+
+/**
+ * Handle keyboard input for navigation
+ */
+int handle_diff_input(DiffViewer *viewer, char key);
+
+/**
+ * Run the interactive diff viewer
+ */
+int run_diff_viewer(void);
+
+/**
+ * Clean up diff viewer resources
+ */
+void cleanup_diff_viewer(DiffViewer *viewer);
+
+/**
+ * Get terminal size
+ */
+void get_terminal_size(int *width, int *height);
+
+/**
+ * Set terminal to raw mode for interactive input
+ */
+void set_raw_mode(struct termios *orig_termios);
+
+/**
+ * Restore terminal to original mode
+ */
+void restore_terminal_mode(struct termios *orig_termios);
+
+#endif // DIFF_VIEWER_H
\ No newline at end of file
diff --git a/diff_viewer.o b/diff_viewer.o
new file mode 100644
index 0000000..d228ea7
Binary files /dev/null and b/diff_viewer.o differ
diff --git a/git_integration.o b/git_integration.o
index 435fca0..df4ac64 100644
Binary files a/git_integration.o and b/git_integration.o differ
diff --git a/line_reader.o b/line_reader.o
index ce74f9b..39249f5 100644
Binary files a/line_reader.o and b/line_reader.o differ
diff --git a/shell b/shell
index ed2ba6c..7d8ffb3 100755
Binary files a/shell and b/shell differ
diff --git a/shell.o b/shell.o
index 6cb9719..80237fb 100644
Binary files a/shell.o and b/shell.o differ
diff --git a/test.txt b/test.txt
index 401006f..861fb62 100644
--- a/test.txt
+++ b/test.txt
@@ -3,3 +3,5 @@ This is a test file for the grep command
 It contains multiple lines
 Boyer-Moore algorithm
 testing the grep
+This is a test change
+Modified test.txt content
diff --git a/test_file_for_diff.txt b/test_file_for_diff.txt
new file mode 100644
index 0000000..bdb3efc
--- /dev/null
+++ b/test_file_for_diff.txt
@@ -0,0 +1,6 @@
+// New test file
+#include <stdio.h>
+int main() {
+    printf("Hello world\n");
+    return 0;
+}