diff --git a/dangerzone/cli.py b/dangerzone/cli.py
index c451856..190be6a 100644
--- a/dangerzone/cli.py
+++ b/dangerzone/cli.py
@@ -5,8 +5,10 @@ from typing import Any, Callable, List, Optional, TypeVar
 import click
 from colorama import Back, Fore, Style
 
-from . import args, errors, isolation_provider
+from . import args, errors
 from .document import ARCHIVE_SUBDIR, SAFE_EXTENSION
+from .isolation_provider.container import Container
+from .isolation_provider.dummy import Dummy
 from .logic import DangerzoneCore
 from .util import get_version
 
diff --git a/dangerzone/gui/__init__.py b/dangerzone/gui/__init__.py
index 5c0a7ca..1a948e6 100644
--- a/dangerzone/gui/__init__.py
+++ b/dangerzone/gui/__init__.py
@@ -13,6 +13,8 @@ from PySide2 import QtCore, QtGui, QtWidgets
 
 from .. import args, errors
 from ..document import Document
+from ..isolation_provider.container import Container
+from ..isolation_provider.dummy import Dummy
 from ..util import get_resource_path, get_version
 from .logic import DangerzoneGui
 from .main_window import MainWindow
diff --git a/dangerzone/gui/logic.py b/dangerzone/gui/logic.py
index b6b7c73..0ca19f8 100644
--- a/dangerzone/gui/logic.py
+++ b/dangerzone/gui/logic.py
@@ -13,6 +13,7 @@ from PySide2 import QtCore, QtGui, QtWidgets
 if platform.system() == "Linux":
     from xdg.DesktopEntry import DesktopEntry
 
+from ..isolation_provider.base import IsolationProvider
 from ..logic import DangerzoneCore
 from ..settings import Settings
 from ..util import get_resource_path
diff --git a/dangerzone/gui/main_window.py b/dangerzone/gui/main_window.py
index f014fe5..c288ca7 100644
--- a/dangerzone/gui/main_window.py
+++ b/dangerzone/gui/main_window.py
@@ -11,8 +11,10 @@ from typing import List, Optional
 from colorama import Fore, Style
 from PySide2 import QtCore, QtGui, QtWidgets
 
-from .. import errors, isolation_provider
+from .. import errors
 from ..document import SAFE_EXTENSION, Document
+from ..isolation_provider.container import Container, NoContainerTechException
+from ..isolation_provider.dummy import Dummy
 from ..util import get_resource_path, get_subprocess_startupinfo, get_version
 from .logic import Alert, DangerzoneGui
 
@@ -167,8 +169,11 @@ class WaitingWidget(QtWidgets.QWidget):
         state: Optional[str] = None
 
         try:
-            container_runtime = self.dangerzone.isolation_provider.get_runtime()
-        except isolation_provider.NoContainerTechException as e:
+            if isinstance(  # Sanity check
+                self.dangerzone.isolation_provider, Container
+            ):
+                container_runtime = self.dangerzone.isolation_provider.get_runtime()
+        except NoContainerTechException as e:
             log.error(str(e))
             state = "not_installed"
 
diff --git a/dangerzone/isolation_provider/__init__.py b/dangerzone/isolation_provider/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/dangerzone/isolation_provider/base.py b/dangerzone/isolation_provider/base.py
new file mode 100644
index 0000000..06c552e
--- /dev/null
+++ b/dangerzone/isolation_provider/base.py
@@ -0,0 +1,118 @@
+import logging
+import subprocess
+from abc import ABC, abstractmethod
+from typing import Callable, Optional
+
+from ..document import Document
+
+log = logging.getLogger(__name__)
+
+
+class IsolationProvider(ABC):
+    """
+    Abstracts an isolation provider
+    """
+
+    @abstractmethod
+    def install(self) -> bool:
+        pass
+
+    def convert(
+        self,
+        document: Document,
+        ocr_lang: Optional[str],
+        stdout_callback: Optional[Callable] = None,
+    ) -> None:
+        document.mark_as_converting()
+        success = self._convert(document, ocr_lang, stdout_callback)
+        if success:
+            document.mark_as_safe()
+            if document.archive_after_conversion:
+                document.archive()
+        else:
+            document.mark_as_failed()
+
+    @abstractmethod
+    def _convert(
+        self,
+        document: Document,
+        ocr_lang: Optional[str],
+        stdout_callback: Optional[Callable] = None,
+    ) -> bool:
+        pass
+
+    @abstractmethod
+    def get_max_parallel_conversions(self) -> int:
+        pass
+
+
+# From global_common:
+
+# def validate_convert_to_pixel_output(self, common, output):
+#     """
+#     Take the output from the convert to pixels tasks and validate it. Returns
+#     a tuple like: (success (boolean), error_message (str))
+#     """
+#     max_image_width = 10000
+#     max_image_height = 10000
+
+#     # Did we hit an error?
+#     for line in output.split("\n"):
+#         if (
+#             "failed:" in line
+#             or "The document format is not supported" in line
+#             or "Error" in line
+#         ):
+#             return False, output
+
+#     # How many pages was that?
+#     num_pages = None
+#     for line in output.split("\n"):
+#         if line.startswith("Document has "):
+#             num_pages = line.split(" ")[2]
+#             break
+#     if not num_pages or not num_pages.isdigit() or int(num_pages) <= 0:
+#         return False, "Invalid number of pages returned"
+#     num_pages = int(num_pages)
+
+#     # Make sure we have the files we expect
+#     expected_filenames = []
+#     for i in range(1, num_pages + 1):
+#         expected_filenames += [
+#             f"page-{i}.rgb",
+#             f"page-{i}.width",
+#             f"page-{i}.height",
+#         ]
+#     expected_filenames.sort()
+#     actual_filenames = os.listdir(common.pixel_dir.name)
+#     actual_filenames.sort()
+
+#     if expected_filenames != actual_filenames:
+#         return (
+#             False,
+#             f"We expected these files:\n{expected_filenames}\n\nBut we got these files:\n{actual_filenames}",
+#         )
+
+#     # Make sure the files are the correct sizes
+#     for i in range(1, num_pages + 1):
+#         with open(f"{common.pixel_dir.name}/page-{i}.width") as f:
+#             w_str = f.read().strip()
+#         with open(f"{common.pixel_dir.name}/page-{i}.height") as f:
+#             h_str = f.read().strip()
+#         w = int(w_str)
+#         h = int(h_str)
+#         if (
+#             not w_str.isdigit()
+#             or not h_str.isdigit()
+#             or w <= 0
+#             or w > max_image_width
+#             or h <= 0
+#             or h > max_image_height
+#         ):
+#             return False, f"Page {i} has invalid geometry"
+
+#         # Make sure the RGB file is the correct size
+#         if os.path.getsize(f"{common.pixel_dir.name}/page-{i}.rgb") != w * h * 3:
+#             return False, f"Page {i} has an invalid RGB file size"
+
+#     return True, True
diff --git a/dangerzone/isolation_provider.py b/dangerzone/isolation_provider/container.py
similarity index 73%
rename from dangerzone/isolation_provider.py
rename to dangerzone/isolation_provider/container.py
index ec41de7..46db661 100644
--- a/dangerzone/isolation_provider.py
+++ b/dangerzone/isolation_provider/container.py
@@ -7,14 +7,14 @@ import platform
 import shutil
 import subprocess
 import tempfile
-from abc import ABC, abstractmethod
 from typing import Callable, List, Optional, Tuple
 
 import appdirs
 from colorama import Fore, Style
 
-from .document import Document
-from .util import get_resource_path, get_subprocess_startupinfo
+from ..document import Document
+from ..util import get_resource_path, get_subprocess_startupinfo
+from .base import IsolationProvider
 
 # Define startupinfo for subprocesses
 if platform.system() == "Windows":
@@ -23,6 +23,7 @@ if platform.system() == "Windows":
 else:
     startupinfo = None
 
+
 log = logging.getLogger(__name__)
 
 
@@ -31,45 +32,7 @@ class NoContainerTechException(Exception):
         super().__init__(f"{container_tech} is not installed")
 
 
-class AbstractIsolationProvider(ABC):
-    """
-    Abstracts an isolation provider
-    """
-
-    @abstractmethod
-    def install(self) -> bool:
-        pass
-
-    def convert(
-        self,
-        document: Document,
-        ocr_lang: Optional[str],
-        stdout_callback: Optional[Callable] = None,
-    ) -> None:
-        document.mark_as_converting()
-        success = self._convert(document, ocr_lang, stdout_callback)
-        if success:
-            document.mark_as_safe()
-            if document.archive_after_conversion:
-                document.archive()
-        else:
-            document.mark_as_failed()
-
-    @abstractmethod
-    def _convert(
-        self,
-        document: Document,
-        ocr_lang: Optional[str],
-        stdout_callback: Optional[Callable] = None,
-    ) -> bool:
-        pass
-
-    @abstractmethod
-    def get_max_parallel_conversions(self) -> int:
-        pass
-
-
-class Container(AbstractIsolationProvider):
+class Container(IsolationProvider):
 
     # Name of the dangerzone container
     CONTAINER_NAME = "dangerzone.rocks/dangerzone"
@@ -355,75 +318,3 @@ class Container(AbstractIsolationProvider):
             n_cpu = int(n_cpu_str.strip())
 
         return 2 * n_cpu + 1
-
-
-# From global_common:
-
-# def validate_convert_to_pixel_output(self, common, output):
-#     """
-#     Take the output from the convert to pixels tasks and validate it. Returns
-#     a tuple like: (success (boolean), error_message (str))
-#     """
-#     max_image_width = 10000
-#     max_image_height = 10000
-
-#     # Did we hit an error?
-#     for line in output.split("\n"):
-#         if (
-#             "failed:" in line
-#             or "The document format is not supported" in line
-#             or "Error" in line
-#         ):
-#             return False, output
-
-#     # How many pages was that?
-#     num_pages = None
-#     for line in output.split("\n"):
-#         if line.startswith("Document has "):
-#             num_pages = line.split(" ")[2]
-#             break
-#     if not num_pages or not num_pages.isdigit() or int(num_pages) <= 0:
-#         return False, "Invalid number of pages returned"
-#     num_pages = int(num_pages)
-
-#     # Make sure we have the files we expect
-#     expected_filenames = []
-#     for i in range(1, num_pages + 1):
-#         expected_filenames += [
-#             f"page-{i}.rgb",
-#             f"page-{i}.width",
-#             f"page-{i}.height",
-#         ]
-#     expected_filenames.sort()
-#     actual_filenames = os.listdir(common.pixel_dir.name)
-#     actual_filenames.sort()
-
-#     if expected_filenames != actual_filenames:
-#         return (
-#             False,
-#             f"We expected these files:\n{expected_filenames}\n\nBut we got these files:\n{actual_filenames}",
-#         )
-
-#     # Make sure the files are the correct sizes
-#     for i in range(1, num_pages + 1):
-#         with open(f"{common.pixel_dir.name}/page-{i}.width") as f:
-#             w_str = f.read().strip()
-#         with open(f"{common.pixel_dir.name}/page-{i}.height") as f:
-#             h_str = f.read().strip()
-#         w = int(w_str)
-#         h = int(h_str)
-#         if (
-#             not w_str.isdigit()
-#             or not h_str.isdigit()
-#             or w <= 0
-#             or w > max_image_width
-#             or h <= 0
-#             or h > max_image_height
-#         ):
-#             return False, f"Page {i} has invalid geometry"
-
-#         # Make sure the RGB file is the correct size
-#         if os.path.getsize(f"{common.pixel_dir.name}/page-{i}.rgb") != w * h * 3:
-#             return False, f"Page {i} has an invalid RGB file size"
-
-#     return True, True
diff --git a/dangerzone/isolation_provider/dummy.py b/dangerzone/isolation_provider/dummy.py
new file mode 100644
index 0000000..03529fe
--- /dev/null
+++ b/dangerzone/isolation_provider/dummy.py
@@ -0,0 +1,89 @@
+import logging
+import os
+import shutil
+import sys
+import time
+from typing import Callable, Optional
+
+from colorama import Fore, Style
+
+from ..document import Document
+from ..util import get_resource_path
+from .base import IsolationProvider
+
+log = logging.getLogger(__name__)
+
+
+class Dummy(IsolationProvider):
+    """Dummy Isolation Provider (FOR TESTING ONLY)
+
+    "Do-nothing" converter - the sanitized files are the same as the input files.
+    Useful for testing without the need to use docker.
+    """
+
+    def __init__(self) -> None:
+        # Sanity check
+        if not getattr(sys, "dangerzone_dev", False):
+            raise Exception(
+                "Dummy isolation provider is UNSAFE and should never be "
+                + "called in a non-testing system."
+            )
+
+    def install(self) -> bool:
+        pass
+
+    def _convert(
+        self,
+        document: Document,
+        ocr_lang: Optional[str],
+        stdout_callback: Optional[Callable] = None,
+    ) -> bool:
+        log.debug("Dummy converter started:")
+        log.debug(
+            f"  - document: {os.path.basename(document.input_filename)} ({document.id})"
+        )
+        log.debug(f"  - ocr     : {ocr_lang}")
+        log.debug("\n(simulating conversion)")
+
+        success = True
+
+        progress = [
+            [False, "Converting to PDF using GraphicsMagick", 0.0],
+            [False, "Separating document into pages", 3.0],
+            [False, "Converting page 1/1 to pixels", 5.0],
+            [False, "Converted document to pixels", 50.0],
+            [False, "Converting page 1/1 from pixels to PDF", 50.0],
+            [False, "Merging 1 pages into a single PDF", 95.0],
+            [False, "Compressing PDF", 97.0],
+            [False, "Safe PDF created", 100.0],
+        ]
+
+        for (error, text, percentage) in progress:
+            self._print_progress(document, error, text, percentage)  # type: ignore [arg-type]
+            if stdout_callback:
+                stdout_callback(error, text, percentage)
+            if error:
+                success = False
+            time.sleep(0.2)
+
+        if success:
+            shutil.copy(
+                get_resource_path("dummy_document.pdf"), document.output_filename
+            )
+
+        return success
+
+    def _print_progress(
+        self, document: Document, error: bool, text: str, percentage: float
+    ) -> None:
+        s = Style.BRIGHT + Fore.YELLOW + f"[doc {document.id}] "
+        s += Fore.CYAN + f"{percentage}% "
+        if error:
+            s += Style.RESET_ALL + Fore.RED + text
+            log.error(s)
+        else:
+            s += Style.RESET_ALL + text
+            log.info(s)
+
+    def get_max_parallel_conversions(self) -> int:
+        return 1
diff --git a/dangerzone/logic.py b/dangerzone/logic.py
index c83527b..d7e8187 100644
--- a/dangerzone/logic.py
+++ b/dangerzone/logic.py
@@ -14,6 +14,7 @@ import colorama
 
 from . import errors, isolation_provider
 from .document import Document
+from .isolation_provider.container import Container
 from .settings import Settings
 from .util import get_resource_path
 
@@ -41,7 +42,7 @@ class DangerzoneCore(object):
 
         self.documents: List[Document] = []
 
-        self.isolation_provider = isolation_provider.Container()
+        self.isolation_provider = Container()
 
     def add_document_from_filename(
         self,