diff --git a/.drone.star b/.drone.star
index 6959d09..e7fd7b7 100644
--- a/.drone.star
+++ b/.drone.star
@@ -99,16 +99,16 @@ def notify_step():
 
 # Builds a notify pipeline that will notify when a dependency fails
 def notify(depends_on=None):
-    if depends_on is None:
+    if not depends_on:
         depends_on = ["tests"]
 
-    return list(dict(
-        kind="pipeline",
-        name="notify",
-        depends_on=depends_on,
-        trigger=dict(status=["failure"]),
-        steps=[notify_step()]
-    ))
+    return [{
+        "kind": "pipeline",
+        "name": "notify",
+        "depends_on": depends_on,
+        "trigger": {"status": ["failure"]},
+        "steps": [notify_step()]
+    }]
 
 
 # Push package to pypi
diff --git a/Makefile b/Makefile
index f8db855..d4b9aa0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 OPEN_CMD := $(shell type xdg-open &> /dev/null && echo 'xdg-open' || echo 'open')
-NAME := paddy
+NAME := padio
 ENV := env
 
 .PHONY: default
@@ -98,19 +98,3 @@ htmlcov/index.html: .coverage
 .PHONY: open-coverage
 open-coverage: htmlcov/index.html
 	$(OPEN_CMD) htmlcov/index.html
-
-# Cleans out docs
-.PHONY: docs-clean
-docs-clean:
-	rm -fr docs/build/* docs/source/code/*
-
-# Builds docs
-docs/build/html/index.html:
-	$(ENV)/bin/tox -e docs
-
-# Shorthand for building docs
-.PHONY: docs
-docs: docs/build/html/index.html
-
-.PHONY: clean-all
-clean-all: clean dist-clean docs-clean
diff --git a/README.md b/README.md
index c1075a2..a9c6396 100644
--- a/README.md
+++ b/README.md
@@ -1,7 +1,49 @@
-# paddy
+# padio
 
 Zero pad numeric filenames
 
+Turn a bunch of files like this:
+
+    file1.txt
+    file10.txt
+    file5.txt
+
+and want them to be sorted like this:
+
+    file01.txt
+    file05.txt
+    file10.txt
+
+you can run:
+
+    padio *.txt
+
+
+## Installation
+
+    pip install padio
+
+## Usage
+
+    usage: padio [-h] [-l LENGTH] [-f] [-v] [-d] [-i REGEX] [--ignore-files IGNOREFILE [IGNOREFILE ...]] file [file ...]
+
+    Pads numbers in file names so they consistently align and sort
+
+    positional arguments:
+      file                  Files to be renamed
+
+    optional arguments:
+      -h, --help            show this help message and exit
+      -l LENGTH, --length LENGTH
+                            Length of numbers after padding (default: auto)
+      -f, --force           Force rename, even if file at destination exists
+      -v, --verbose         Print all actions
+      -d, --dry-run         Print actions only without modifying any file. Implies --verbose
+      -i REGEX, --ignore REGEX
+                            Regular expression used to ignore files matching the name
+      --ignore-files IGNOREFILE [IGNOREFILE ...]
+                            Files to ignore for renaming. Must add -- before positional arguments
+
 ## Original repo
 
-Originally hosted at https://git.iamthefij.com/iamthefij/paddy.git
+Originally hosted at https://git.iamthefij.com/iamthefij/padio.git
diff --git a/docs/source/conf.py b/docs/source/conf.py
deleted file mode 100644
index d5a275a..0000000
--- a/docs/source/conf.py
+++ /dev/null
@@ -1,52 +0,0 @@
-# Configuration file for the Sphinx documentation builder.
-#
-# This file only contains a selection of the most common options. For a full
-# list see the documentation:
-# https://www.sphinx-doc.org/en/master/usage/configuration.html
-
-# -- Path setup --------------------------------------------------------------
-
-# If extensions (or modules to document with autodoc) are in another directory,
-# add these directories to sys.path here. If the directory is relative to the
-# documentation root, use os.path.abspath to make it absolute, like shown here.
-#
-# import os
-# import sys
-# sys.path.insert(0, os.path.abspath('.'))
-
-
-# -- Project information -----------------------------------------------------
-
-project = 'paddy'
-copyright = '2021, iamthefij'
-author = 'iamthefij'
-
-
-# -- General configuration ---------------------------------------------------
-
-# Add any Sphinx extension module names here, as strings. They can be
-# extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
-# ones.
-extensions = [
-]
-
-# Add any paths that contain templates here, relative to this directory.
-templates_path = ['_templates']
-
-# List of patterns, relative to source directory, that match files and
-# directories to ignore when looking for source files.
-# This pattern also affects html_static_path and html_extra_path.
-exclude_patterns = []
-
-
-# -- Options for HTML output -------------------------------------------------
-
-# The theme to use for HTML and HTML Help pages.  See the documentation for
-# a list of builtin themes.
-#
-html_theme = 'alabaster'
-
-# Add any paths that contain custom static files (such as style sheets) here,
-# relative to this directory. They are copied after the builtin static files,
-# so a file named "default.css" will overwrite the builtin "default.css".
-html_static_path = ['_static']
\ No newline at end of file
diff --git a/docs/source/index.rst b/docs/source/index.rst
deleted file mode 100644
index fb3b750..0000000
--- a/docs/source/index.rst
+++ /dev/null
@@ -1,20 +0,0 @@
-.. paddy documentation master file, created by
-   sphinx-quickstart on Fri Feb  5 15:06:05 2021.
-   You can adapt this file completely to your liking, but it should at least
-   contain the root `toctree` directive.
-
-Welcome to paddy's documentation!
-========================================
-
-.. toctree::
-   :maxdepth: 2
-   :caption: Contents:
-
-
-
-Indices and tables
-==================
-
-* :ref:`genindex`
-* :ref:`modindex`
-* :ref:`search`
diff --git a/padio.py b/padio.py
new file mode 100755
index 0000000..e6468f7
--- /dev/null
+++ b/padio.py
@@ -0,0 +1,155 @@
+#! /usr/bin/env python3
+# -*- coding: utf-8 -*-
+import argparse
+import re
+from pathlib import Path
+from typing import Generator
+from typing import List
+from typing import Optional
+from typing import Tuple
+
+
+num_matcher = re.compile(r"([0-9]+)")
+
+
+def extract_numbers(s: str) -> str:
+    number_match = num_matcher.search(s)
+    if number_match:
+        return number_match.group(1)
+    return ""
+
+
+def calc_pad_length(files: List[Path]) -> int:
+    max_len = 0
+    for f in files:
+        numbers = extract_numbers(f.name)
+        max_len = max(len(numbers), max_len)
+    return max_len
+
+
+def parse_args(sys_args: Optional[List[str]] = None) -> argparse.Namespace:
+    parser = argparse.ArgumentParser(
+        description="Pads numbers in file names so they consistently align and sort"
+    )
+    parser.add_argument("files", nargs="+", metavar="file", help="Files to be renamed")
+    parser.add_argument(
+        "-l",
+        "--length",
+        type=int,
+        help="Length of numbers after padding (default: auto)",
+    )
+    parser.add_argument(
+        "-f",
+        "--force",
+        action="store_true",
+        help="Force rename, even if file at destination exists",
+    )
+    parser.add_argument(
+        "-v", "--verbose", action="store_true", help="Print all actions"
+    )
+    parser.add_argument(
+        "-d",
+        "--dry-run",
+        action="store_true",
+        help="Print actions only without modifying any file. Implies --verbose",
+    )
+    parser.add_argument(
+        "-i",
+        "--ignore",
+        metavar="REGEX",
+        help="Regular expression used to ignore files matching the name",
+    )
+    parser.add_argument(
+        "--ignore-files",
+        nargs="+",
+        metavar="IGNOREFILE",
+        help="Files to ignore for renaming. Must add -- before positional arguments",
+    )
+    args = parser.parse_args(sys_args)
+
+    # Dry run implies verbose
+    if args.dry_run:
+        args.verbose = True
+
+    return args
+
+
+def get_files(
+    filenames: List[str],
+    ignore_filenames: List[str],
+    ignore_pattern: str,
+) -> List[Path]:
+    # Compile ignore pattern, if provided
+    ignore_matcher: Optional[re.Pattern] = None
+    if ignore_pattern:
+        ignore_matcher = re.compile(ignore_pattern)
+
+    p = Path(".")
+    files: List[Path] = []
+    for f in filenames:
+        if ignore_filenames and f in ignore_filenames:
+            continue
+        if ignore_matcher and ignore_matcher.match(f):
+            continue
+        files.append(p / f)
+
+    return files
+
+
+def pad_files(
+    files: List[Path],
+    pad_len: int,
+    verbose=False,
+) -> Generator[Tuple[Path, Path], None, None]:
+    for f in files:
+        numbers = extract_numbers(f.name)
+        if len(numbers) == pad_len:
+            if verbose:
+                print(f"{f.name} is already padded.")
+            continue
+
+        # Pad number and get destination path
+        new_numbers = numbers.zfill(pad_len)
+        new_name = num_matcher.sub(new_numbers, f.name, count=1)
+        new_file = f.parent / new_name
+
+        if f == new_file:
+            if verbose:
+                print(f"{f.name} already matches destination.")
+            continue
+
+        yield f, new_file
+
+
+def main(sys_args: Optional[List[str]] = None) -> int:
+    args = parse_args(sys_args)
+
+    # Build list of files to act on
+    files = get_files(args.files, args.ignore_files, args.ignore)
+
+    pad_len = args.length
+    if pad_len is None:
+        pad_len = calc_pad_length(files)
+
+    if args.verbose:
+        print(f"Padding to {pad_len}")
+
+    status = 0
+    for f, new_file in pad_files(files, pad_len, args.verbose):
+        # Possibly rename unless exists or forced
+        if not new_file.exists() or args.force:
+            if args.verbose:
+                print(f"Rename {f.name} to {new_file.name}")
+            if not args.dry_run:
+                f.rename(new_file)
+        else:
+            print(
+                f"Could not rename {f.name} to {new_file.name}. Destination file exists."
+            )
+            status = 1
+
+    return status
+
+
+if __name__ == "__main__":
+    exit(main())
diff --git a/requirements-dev.txt b/requirements-dev.txt
new file mode 100644
index 0000000..0d340f7
--- /dev/null
+++ b/requirements-dev.txt
@@ -0,0 +1,3 @@
+-e .
+pytest
+coverage
diff --git a/setup.py b/setup.py
index aa10266..5d86eb9 100644
--- a/setup.py
+++ b/setup.py
@@ -11,13 +11,13 @@ with open(path.join(here, "README.md"), encoding="utf-8") as f:
     long_description = f.read()
 
 setup(
-    name="paddy",
+    name="padio",
     version="0.0.0",
     description="Zero pad numeric filenames",
     long_description=long_description,
     long_description_content_type="text/markdown",
-    url="https://git.iamthefij.com/iamthefij/paddy.git",
-    download_url=("https://git.iamthefij.com/iamthefij/paddy.git/archive/master.tar.gz"),
+    url="https://git.iamthefij.com/iamthefij/padio.git",
+    download_url=("https://git.iamthefij.com/iamthefij/padio.git/archive/master.tar.gz"),
     author="iamthefij",
     author_email="",
     classifiers=[
@@ -39,7 +39,7 @@ setup(
     install_requires=[],
     entry_points={
         "console_scripts": [
-            "paddy=paddy.main:main",
+            "padio=padio:main",
         ],
     },
 )
diff --git a/tests/test_paddy.py b/tests/test_paddy.py
new file mode 100644
index 0000000..24230a2
--- /dev/null
+++ b/tests/test_paddy.py
@@ -0,0 +1,90 @@
+from pathlib import Path
+
+import pytest
+
+import padio
+
+
+@pytest.mark.parametrize(
+    "value,expected",
+    (
+        ("file123", "123"),
+        ("123file", "123"),
+        ("123file456", "123"),
+        ("file", ""),
+    ),
+)
+def test_extract_numbers(value, expected):
+    assert padio.extract_numbers(value) == expected
+
+
+@pytest.mark.parametrize(
+    "file_paths,expected",
+    (
+        ([Path("/path/to/file.a123.txt"), Path("/path/to/file.b123.txt")], 3),
+        ([Path("/path/to/file.a023.txt"), Path("/path/to/file.b023.txt")], 3),
+        ([Path("/path/to/file.a123.txt"), Path("/path/to/file.b12.txt")], 3),
+    ),
+)
+def test_calc_pad_length(file_paths, expected):
+    assert padio.calc_pad_length(file_paths) == expected
+
+
+@pytest.mark.parametrize(
+    "files,ignore_files,ignore,expected",
+    (
+        (
+            [
+                "file.a123.txt",
+                "file.b123.txt",
+            ],
+            [],
+            "",
+            [
+                Path("./file.a123.txt"),
+                Path("./file.b123.txt"),
+            ],
+        ),
+        (
+            [
+                "file.a123.txt",
+                "file.b123.txt",
+            ],
+            [
+                "file.a123.txt",
+            ],
+            "",
+            [
+                Path("./file.b123.txt"),
+            ],
+        ),
+        (
+            [
+                "file.a123.txt",
+                "file.b123.txt",
+                "ignore.txt"
+            ],
+            [
+                "file.a123.txt",
+            ],
+            "ignore.*",
+            [
+                Path("./file.b123.txt"),
+            ],
+        ),
+    ),
+)
+def test_get_files(files, ignore_files, ignore, expected):
+    assert padio.get_files(files, ignore_files, ignore) == expected
+
+
+@pytest.mark.parametrize(
+    "files,pad_len,expected",
+    (
+        ([Path("./file.a12")], 1, []),
+        ([Path("./file.a12")], 2, []),
+        ([Path("./file.a12")], 3, [Path("./file.a012")]),
+    ),
+)
+def test_pad_files(files, pad_len, expected):
+    assert list(padio.pad_files(files, pad_len)) == list(zip(files, expected))
diff --git a/tox.ini b/tox.ini
index 518f7a7..1b83338 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,13 +1,13 @@
 [tox]
-envlist = py3,pypy3
+envlist = py3,py36,py37,py38,pypy3
 
 [testenv]
 deps =
     -rrequirements-dev.txt
 commands =
     coverage erase
-    coverage run --source=paddy/ -m pytest --capture=no -vv {posargs:tests}
-    coverage report -m --fail-under 70
+    coverage run --source=padio -m pytest --capture=no -vv {posargs:tests}
+    coverage report -m --fail-under 50
     pre-commit run --all-files
 
 [testenv:pre-commit]
@@ -15,13 +15,3 @@ deps =
     pre-commit
 commands =
     pre-commit {posargs}
-
-[testenv:docs]
-deps =
-    {[base]deps}
-    sphinx
-    sphinx_rtd_theme
-changedir = docs
-commands =
-    sphinx-apidoc -f -e -o source/code ../paddy
-    sphinx-build -b html -d build/doctrees source/ build/html