diff --git a/README.md b/README.md
index 5bc551a..e907b14 100644
--- a/README.md
+++ b/README.md
@@ -29,6 +29,8 @@ pip install -r requirements.txt
 ```
 # must have venv/venv3 activated
 $ python src/vis.py <root project directory>
+# show help and optional cmd flags
+$ python src/vis.py -h 
 ```
 
 __Example:__
@@ -68,3 +70,12 @@ Also displays with `graphviz`:
 Another example graph from a [slightly more substantial project](https://github.com/nicolashahn/set-solver) (blue arrows/nodes indicate modules where the code does not live in the project directory [such as modules installed through pip]):
 
 ![](examples/set-solver.png)
+
+### Custom filter logic
+
+If not existent create a module `modfilter.py` alongside `vis.py` in src/ and add one or both of the following two callback functions:
+`parent_mod_filter_func(mod_dict: Dict) -> Dict`
+`import_mod_filter_func(modname: str, parentname: str) -> bool`
+
+vis.py checks for a module modfilter.py and these two callback functions as part of the modfilter module and calls them during processing
+if existent to allow for custom filtering of modules. A commented example `modfilter.py` is already included in the project.
diff --git a/src/modfilter.py b/src/modfilter.py
new file mode 100644
index 0000000..978a205
--- /dev/null
+++ b/src/modfilter.py
@@ -0,0 +1,34 @@
+from typing import Callable, Dict
+import sys
+
+def eprint(*args, **kwargs):
+        print(*args, file=sys.stderr, **kwargs)
+
+# function to edit mod_dict and filter out modules from project tree (will be parsed for imports)
+def parent_mod_filter_func(mod_dict: Dict) -> Dict:
+        temp = dict(mod_dict)
+        for name, _ in mod_dict.items(): 
+                if not parent_filter(name):
+                        del temp[name]
+        return temp 
+
+# example filter function for listed modules in project tree
+# return false to exclude module
+def parent_filter(modname: str) -> bool:
+        # example filter logic
+        #return not (is_test_module(modname) or is_logging_module(modname) or is_django_module(modname))
+        return True
+
+# example filterfunction for filtering specific module
+# return false to exclude module 
+def import_mod_filter_func(modname: str, parentname: str) -> bool:
+        # Example filter logic
+        #return not (is_test_module(parentname) or is_logging_module(parentname) or is_django_module(parentname))
+        return True
+
+
+is_test_module: Callable[[str], bool] = lambda modname: '.tests' in modname
+
+is_logging_module: Callable[[str], bool] = lambda modname: 'logging' in modname
+
+is_django_module: Callable[[str], bool] = lambda modname: 'django' in modname
\ No newline at end of file
diff --git a/src/vis.py b/src/vis.py
index 36480f3..78da75f 100644
--- a/src/vis.py
+++ b/src/vis.py
@@ -4,21 +4,26 @@
 
 import argparse
 import dis
+import graphviz
+import importlib.util
 import matplotlib.colors as mc
+import networkx as nx
 import os
 import platform
 import sys
 from collections import defaultdict
+from libinfo import is_std_lib_module
 from modulefinder import ModuleFinder, Module as MFModule
 from matplotlib.colors import hsv_to_rgb
-from pyvis.network import Network
-import networkx as nx
 from networkx.drawing.nx_pydot import write_dot
+from pyvis.network import Network
+from typing import Callable
 
-import graphviz
-
-from libinfo import is_std_lib_module
 
+if importlib.util.find_spec('modfilter', __package__) is not None:
+    import modfilter
+else:
+    modfilter = None
 
 # actual opcodes
 LOAD_CONST = dis.opmap["LOAD_CONST"]
@@ -48,6 +53,10 @@
 JAVA_SYSTEM_NAME    = "Java"
 WINDOWS_SYSTEM_NAME = "Windows"
 
+# function for logging (to stderr)
+def eprint(*args, **kwargs):
+    print(*args, file=sys.stderr, **kwargs)
+
 def abs_mod_name(module, root_dir):
     """ From a Module's absolute path, and the root directory, return a
     string with how that module would be imported from a script in the root
@@ -72,7 +81,6 @@ def abs_mod_name(module, root_dir):
     mod_name = ".".join(path_parts)
     return mod_name
 
-
 def get_modules_from_file(script, root_dir=None, use_sys_path=False):
     """ Use ModuleFinder.load_file() to get module imports for the given
     script.
@@ -107,7 +115,6 @@ def get_modules_from_file(script, root_dir=None, use_sys_path=False):
 
     return modules
 
-
 def get_modules_in_dir(root_dir, ignore_venv=True):
     """ Walk a directory recursively and get the module imports for all .py
     files in the directory.
@@ -130,7 +137,6 @@ def get_modules_in_dir(root_dir, ignore_venv=True):
                     mods[mod_name] = mod
     return mods
 
-
 class Module(MFModule, object):
     """ Extension of modulefinder.ModuleFinder to add custom attrs. """
 
@@ -141,7 +147,6 @@ def __init__(self, *args, **kwargs):
         # value = list of names imported from that module
         self.direct_imports = {}
 
-
 def _unpack_opargs(code):
     """ Step through the python bytecode and generate a tuple (int, int, int):
     (operation_index, operation_byte, argument_byte) for each operation.
@@ -170,7 +175,6 @@ def _unpack_opargs(code):
             yield (i, op, arg)
     # Python 1?
 
-
 def scan_opcodes(compiled):
     """
     This function is stolen w/ slight modifications from the standard library
@@ -214,8 +218,7 @@ def scan_opcodes(compiled):
                 yield REL_IMPORT, (level, fromlist, names[oparg])
             continue
 
-
-def get_fq_immediate_deps(all_mods, module):
+def get_fq_immediate_deps(all_mods, module, modfilterfunc: Callable[[str, str], bool]=lambda name, parentname: True):
     """
     From a Module, using the module's absolute path, compile the code and then
     search through it for the imports and get a list of the immediately
@@ -240,13 +243,18 @@ def get_fq_immediate_deps(all_mods, module):
             if op == ABS_IMPORT:
                 names, top = args
                 if (
-                    not is_std_lib_module(top.split(".")[0], PY_VERSION)
-                    or top in all_mods
+                    (not is_std_lib_module(top.split(".")[0], PY_VERSION)
+                    or top in all_mods)
+                    and modfilterfunc("", top)
                 ):
                     if not names:
                         fq_deps[top].append([])
                     for name in names:
                         fq_name = top + "." + name
+                        if not modfilterfunc(name, top):
+                            eprint("EXCLUDE: ", top, "->", name)
+                            continue
+
                         if fq_name in all_mods:
                             # just to make sure it's in the dict
                             fq_deps[fq_name].append([])
@@ -259,17 +267,15 @@ def get_fq_immediate_deps(all_mods, module):
 
     return fq_deps
 
-
-def add_immediate_deps_to_modules(mod_dict):
+def add_immediate_deps_to_modules(mod_dict, modfilterfunc: Callable[[str, str], bool]=lambda name, parentname: True):
     """ Take a module dictionary, and add the names of the modules directly
     imported by each module in the dictionary, and add them to the module's
     direct_imports.
     """
     for name, module in sorted(mod_dict.items()):
-        fq_deps = get_fq_immediate_deps(mod_dict, module)
+        fq_deps = get_fq_immediate_deps(mod_dict, module, modfilterfunc=modfilterfunc)
         module.direct_imports = fq_deps
 
-
 def mod_dict_to_dag(mod_dict, graph_name):
     """ Take a module dictionary, and return a graphviz.Digraph object
     representing the module import relationships. """
@@ -288,7 +294,6 @@ def mod_dict_to_dag(mod_dict, graph_name):
             dag.edge(name, di, **attrs)
     return dag
 
-
 def get_args():
     """ Parse and return command line args. """
     parser = argparse.ArgumentParser(
@@ -328,7 +333,6 @@ def get_args():
     # help='file that contains names of modules to ignore')
     return parser.parse_args()
 
-
 def generate_pyvis_visualization(mod_dict, dotfile='', show=False):
     def get_hex_color_of_shade(value):
         if value < 0 or value > 1:
@@ -409,6 +413,8 @@ def normaliz_between_n1_1(min, max, val):
 
 def main():
 
+    endnotice = False
+
     args = get_args()
     if args.path[-3:] == ".py":
         script = args.path
@@ -419,9 +425,24 @@ def main():
     else:
         root_dir = args.path
         mod_dict = get_modules_in_dir(root_dir)
-    
-        
-    add_immediate_deps_to_modules(mod_dict)
+
+    # check for filterfunction callback to be present, else use stub lambda
+    if modfilter is None:
+        add_immediate_deps_to_modules(mod_dict)
+    else:
+        match hasattr(modfilter, "parent_mod_filter_func"):
+            case True:
+                mod_dict = modfilter.parent_mod_filter_func(mod_dict)
+        match hasattr(modfilter, "import_mod_filter_func"):
+            case False:
+                add_immediate_deps_to_modules(mod_dict)
+            case True:
+                add_immediate_deps_to_modules(mod_dict, modfilterfunc=modfilter.import_mod_filter_func)
+
+        # print notice to either implement one of the callbacks or consider removing modfilter module
+        if not hasattr(modfilter, "parent_mod_filter_func") and hasattr(modfilter, "import_mod_filter_func"):
+            endnotice = True
+
     print("Module dependencies:")
     for name, module in sorted(mod_dict.items()):
         print("\n" + name)
@@ -440,5 +461,8 @@ def main():
     else:
         generate_pyvis_visualization(mod_dict, show=args.show_graph)
 
+    if endnotice:
+        eprint("Notice: consider adding one of the filter functions (parent_mod_filter_func or import_mod_filter_func) to modfilter module or removing modfilter module completely.")
+
 if __name__ == "__main__":
-    main()
+    main()
\ No newline at end of file