diff --git a/win/tools/1337-diff/1337-diff.py b/win/tools/1337-diff/1337-diff.py
new file mode 100755
index 0000000..c9ab947
--- /dev/null
+++ b/win/tools/1337-diff/1337-diff.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python3
+
+import sys
+import argparse
+import os.path
+import itertools
+
+PATCH_EXT = ".1337"
+CRLF = b"\x0d\x0a"
+HEADER_FORMAT = b">%s"
+LINE_FORMAT = CRLF + b"%016X:%02X->%02X"
+OFFSET_ADJUSTMENT = 0xC00
+
+
+class ByteDiffException(Exception):
+    """ Base class for all exceptions """
+    pass
+
+
+class LengthMismatchException(ByteDiffException):
+    """ Throwed when length of input sequences do not match """
+    pass
+
+
+def check_positive_int(value):
+    value = int(value)
+    if value <= 0:
+        raise argparse.ArgumentTypeError(
+            "%s is an invalid positive number value" % value)
+    return value
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(
+        description="Make .1337 patch file from original and patched files")
+    parser.add_argument("orig_file",
+                        metavar="ORIG_FILE",
+                        help="original file")
+    parser.add_argument("patched_file",
+                        metavar="PATCHED_FILE",
+                        help="patched file")
+    parser.add_argument("output_file",
+                        metavar="OUTPUT_FILE",
+                        nargs='?',
+                        help="filename for patch output. Default: basename of "
+                        "original filename with .1337 extension")
+    parser.add_argument("-f", "--header-filename",
+                        metavar="FILENAME",
+                        help="filename specified in resulting patch header. "
+                        "Default: basename of original filename.")
+    parser.add_argument("-l", "--limit",
+                        help="stop after number of differences",
+                        type=check_positive_int)
+    args = parser.parse_args()
+    return args
+
+
+def feed_chunks(f, chunk_size=4096):
+    """ Reads file-like object with chunks having up to `chunk_size` length """
+    while True:
+        buf = f.read(chunk_size)
+        if not buf:
+            break
+        yield buf
+
+
+def zip_files_bytes(*files):
+    """ Iterate over two files, returning pair of bytes.
+    Throw LengthMismatch if file sizes is uneven. """
+    class EndMarker(object):
+        pass
+    end_marker = EndMarker()
+
+    iterators = (itertools.chain.from_iterable(feed_chunks(f)) for f in files)
+    for tup in itertools.zip_longest(*iterators, fillvalue=end_marker):
+        if any(v is end_marker for v in tup):
+            raise LengthMismatchException("Length of input files inequal.")
+        yield tup
+
+
+def diff(left, right):
+    for offset, (a, b) in enumerate(zip_files_bytes(left, right)):
+        if a != b:
+            yield offset, a, b
+
+
+def compose_diff_file(orig, patched, output, header, offset_adjustment=True):
+    output.write(HEADER_FORMAT % (header.encode('latin-1'),))
+    for offset, a, b in diff(orig, patched):
+        o = offset + OFFSET_ADJUSTMENT if offset_adjustment else offset
+        output.write(LINE_FORMAT % (o, a, b))
+
+
+def main():
+    args = parse_args()
+
+    output_filename = args.output_file
+    if not output_filename:
+        orig_bname = os.path.basename(args.orig_file)
+        before, _, after = orig_bname.rpartition('.')
+        orig_bname_noext = before if before else after
+        output_filename = orig_bname_noext + PATCH_EXT
+
+    header_filename = args.header_filename
+    if not header_filename:
+        header_filename = os.path.basename(args.orig_file)
+
+    with open(args.orig_file, 'rb') as orig,\
+         open(args.patched_file, 'rb') as patched,\
+         open(output_filename, 'wb') as output:
+        try:
+            compose_diff_file(orig, patched, output, header_filename)
+        except LengthMismatchException:
+            print("Input files have inequal length. Aborting...",
+                  file=sys.stderr)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/win/tools/1337-diff/README.md b/win/tools/1337-diff/README.md
new file mode 100644
index 0000000..f6e25e4
--- /dev/null
+++ b/win/tools/1337-diff/README.md
@@ -0,0 +1,46 @@
+1337-diff
+=========
+
+This tool accepts two input files and produces patch (diff) in `.1337`-file format. This format is compatible with patches produced by [x64dbg](https://x64dbg.com/) and applied by [Win\_1337\_Apply\_Patch tool](https://github.com/Deltafox79/Win_1337_Apply_Patch).
+
+This tool is intended for internal usage to automate routine tasks related to windows patches. Implementation is really slow and prefers code transparency and correctness over speed.
+
+## Requirements
+
+* Python 3
+
+## Synopsys
+
+```
+$ ./1337-diff.py -h
+usage: 1337-diff.py [-h] [-f FILENAME] [-l LIMIT]
+                    ORIG_FILE PATCHED_FILE [OUTPUT_FILE]
+
+Make .1337 patch file from original and patched files
+
+positional arguments:
+  ORIG_FILE             original file
+  PATCHED_FILE          patched file
+  OUTPUT_FILE           filename for patch output. Default: basename of
+                        original filename with .1337 extension
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -f FILENAME, --header-filename FILENAME
+                        filename specified in resulting patch header. Default:
+                        basename of original filename.
+  -l LIMIT, --limit LIMIT
+                        stop after number of differences
+```
+
+## Example
+
+```
+$ ./1337-diff.py ~/w418.81/orig/nvcuvid.dll ~/w418.81/patched/nvcuvid.dll 
+$ cat nvcuvid.1337 
+>nvcuvid.dll
+00000000000DE736:74->90
+00000000000DE737:08->90$
+```
+
+Note no newline at the end of file and CRLF line breaks.