diff --git a/barcode/__init__.py b/barcode/__init__.py
index 6a4d481..bbc6b2e 100644
--- a/barcode/__init__.py
+++ b/barcode/__init__.py
@@ -31,10 +31,13 @@
 from barcode.version import version  # noqa: F401
 
 if TYPE_CHECKING:
+    from typing import Any
+
     from barcode.base import Barcode
     from barcode.writer import BaseWriter
+    from barcode.writer import T_Output
 
-__BARCODE_MAP: dict[str, type[Barcode]] = {
+__BARCODE_MAP: dict[str, type[Barcode[Any]]] = {
     "codabar": CODABAR,
     "code128": Code128,
     "code39": Code39,
@@ -59,31 +62,33 @@
     "upca": UPCA,
 }
 
-PROVIDED_BARCODES = list(__BARCODE_MAP)
-PROVIDED_BARCODES.sort()
+PROVIDED_BARCODES = sorted(__BARCODE_MAP)
 
 
 @overload
 def get(
-    name: str, code: str, writer: BaseWriter | None = None, options: dict | None = None
-) -> Barcode: ...
+    name: str,
+    code: str,
+    writer: BaseWriter[T_Output] | None = None,
+    options: dict | None = None,
+) -> Barcode[T_Output]: ...
 
 
 @overload
 def get(
     name: str,
     code: None = None,
-    writer: BaseWriter | None = None,
+    writer: BaseWriter[Any] | None = None,
     options: dict | None = None,
-) -> type[Barcode]: ...
+) -> type[Barcode[Any]]: ...
 
 
 def get(
     name: str,
     code: str | None = None,
-    writer: BaseWriter | None = None,
+    writer: BaseWriter[Any] | None = None,
     options: dict | None = None,
-) -> Barcode | type[Barcode]:
+) -> Barcode[Any] | type[Barcode[Any]]:
     """Helper method for getting a generator or even a generated code.
 
     :param name: The name of the type of barcode desired.
@@ -96,7 +101,6 @@ def get(
         generating.
     """
     options = options or {}
-    barcode: type[Barcode]
     try:
         barcode = __BARCODE_MAP[name.lower()]
     except KeyError as e:
@@ -107,14 +111,14 @@ def get(
     return barcode
 
 
-def get_class(name: str) -> type[Barcode]:
+def get_class(name: str) -> type[Barcode[Any]]:
     return get_barcode(name)
 
 
 def generate(
     name: str,
     code: str,
-    writer: BaseWriter | None = None,
+    writer: BaseWriter[Any] | None = None,
     output: str | os.PathLike | BinaryIO | None = None,
     writer_options: dict | None = None,
     text: str | None = None,
diff --git a/barcode/base.py b/barcode/base.py
index e3aa713..855ddef 100644
--- a/barcode/base.py
+++ b/barcode/base.py
@@ -4,22 +4,25 @@
 
 from typing import TYPE_CHECKING
 from typing import ClassVar
+from typing import Generic
+from typing import overload
 
 from barcode.writer import BaseWriter
 from barcode.writer import SVGWriter
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
+    from collections.abc import Callable
+    from typing import Any
     from typing import BinaryIO
 
-    from PIL.Image import Image as T_Image
 
-
-class Barcode:
+class Barcode(Generic[T_Output]):
     name = ""
 
     digits = 0
 
-    default_writer = SVGWriter
+    default_writer: ClassVar[Callable[[], BaseWriter[Any]]] = SVGWriter
 
     default_writer_options: ClassVar[dict] = {
         "module_width": 0.2,
@@ -33,11 +36,44 @@ class Barcode:
         "text": "",
     }
 
-    writer: BaseWriter
+    writer: BaseWriter[T_Output]
+
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: None = None,
+        **options,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output],
+        **options,
+    ) -> None: ...
 
-    def __init__(self, code: str, writer: BaseWriter | None = None, **options) -> None:
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output] | None = None,
+        **options,
+    ) -> None:
         raise NotImplementedError
 
+    def _resolve_writer(
+        self,
+        writer: BaseWriter[T_Output] | None,
+    ) -> BaseWriter[T_Output]:
+        if writer is not None:
+            return writer
+        # When no writer is given, T_Output falls back to its default (bytes),
+        # which matches what the default writer (SVGWriter) renders. Accessing
+        # default_writer through the class keeps mypy from binding it like a
+        # method.
+        return type(self).default_writer()
+
     def to_ascii(self) -> str:
         code_list = self.build()
         if not len(code_list) == 1:
@@ -64,7 +100,10 @@ def get_fullcode(self) -> str:
         raise NotImplementedError
 
     def save(
-        self, filename: str, options: dict | None = None, text: str | None = None
+        self,
+        filename: str,
+        options: dict | None = None,
+        text: str | None = None,
     ) -> str:
         """Renders the barcode and saves it in `filename`.
 
@@ -98,7 +137,7 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         """Renders the barcode using `self.writer`.
 
         :param writer_options: Options for `self.writer`, see writer docs for details.
diff --git a/barcode/codabar.py b/barcode/codabar.py
index 3ea73cb..86a1f60 100644
--- a/barcode/codabar.py
+++ b/barcode/codabar.py
@@ -8,17 +8,19 @@
 __docformat__ = "restructuredtext en"
 
 from typing import TYPE_CHECKING
+from typing import overload
 
 from barcode.base import Barcode
 from barcode.charsets import codabar
 from barcode.errors import BarcodeError
 from barcode.errors import IllegalCharacterError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
     from barcode.writer import BaseWriter
 
 
-class CODABAR(Barcode):
+class CODABAR(Barcode[T_Output]):
     """Initializes a new CODABAR instance.
 
     :param code: Codabar (NW-7) string that matches [ABCD][0-9$:/.+-]+[ABCD]
@@ -30,15 +32,33 @@ class CODABAR(Barcode):
 
     name = "Codabar (NW-7)"
 
+    @overload
     def __init__(
         self,
         code: str,
-        writer: BaseWriter | None = None,
+        writer: None = None,
+        narrow: int = 2,
+        wide: int = 5,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output],
+        narrow: int = 2,
+        wide: int = 5,
+    ) -> None: ...
+
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output] | None = None,
         narrow: int = 2,
         wide: int = 5,
     ) -> None:
         self.code = code
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
         self.narrow = narrow
         self.wide = wide
 
diff --git a/barcode/codex.py b/barcode/codex.py
index fe82744..0ecdb27 100644
--- a/barcode/codex.py
+++ b/barcode/codex.py
@@ -7,6 +7,7 @@
 
 from typing import TYPE_CHECKING
 from typing import Literal
+from typing import overload
 
 from barcode.base import Barcode
 from barcode.charsets import code39
@@ -14,12 +15,11 @@
 from barcode.errors import BarcodeError
 from barcode.errors import IllegalCharacterError
 from barcode.errors import NumberOfDigitsError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
     from collections.abc import Collection
 
-    from PIL.Image import Image as T_Image
-
     from barcode.writer import BaseWriter
 
 __docformat__ = "restructuredtext en"
@@ -42,15 +42,31 @@ def check_code(code: str, name: str, allowed: Collection[str]) -> None:
         )
 
 
-class Code39(Barcode):
+class Code39(Barcode[T_Output]):
     """A Code39 barcode implementation"""
 
     name = "Code 39"
 
+    @overload
     def __init__(
         self,
         code: str,
-        writer: BaseWriter | None = None,
+        writer: None = None,
+        add_checksum: bool = True,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output],
+        add_checksum: bool = True,
+    ) -> None: ...
+
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output] | None = None,
         add_checksum: bool = True,
     ) -> None:
         r"""
@@ -63,7 +79,7 @@ def __init__(
         self.code = code.upper()
         if add_checksum:
             self.code += self.calculate_checksum()
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
         check_code(self.code, self.name, code39.REF)
 
     def __str__(self) -> str:
@@ -94,13 +110,13 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         options = {"module_width": MIN_SIZE, "quiet_zone": MIN_QUIET_ZONE}
         options.update(writer_options or {})
         return super().render(options, text)
 
 
-class PZN7(Code39):
+class PZN7(Code39[T_Output]):
     """Initializes new German number for pharmaceutical products.
 
     :param pzn: Code to render.
@@ -111,7 +127,13 @@ class PZN7(Code39):
 
     digits = 6
 
-    def __init__(self, pzn: str, writer: BaseWriter | None = None) -> None:
+    @overload
+    def __init__(self, pzn: str, writer: None = None) -> None: ...
+
+    @overload
+    def __init__(self, pzn: str, writer: BaseWriter[T_Output]) -> None: ...
+
+    def __init__(self, pzn: str, writer: BaseWriter[T_Output] | None = None) -> None:
         pzn = pzn[: self.digits]
         if not pzn.isdigit():
             raise IllegalCharacterError("PZN can only contain numbers.")
@@ -126,7 +148,8 @@ def __init__(self, pzn: str, writer: BaseWriter | None = None) -> None:
     def get_fullcode(self) -> str:
         return f"PZN-{self.pzn}"
 
-    def calculate_checksum(self) -> int:
+    # PZN checksums are numeric, unlike Code39's alphanumeric checksum char.
+    def calculate_checksum(self) -> int:  # type: ignore[override]
         sum_ = sum(int(x) * int(y) for x, y in enumerate(self.pzn, start=2))
         checksum = sum_ % 11
         if checksum == 10:
@@ -135,13 +158,13 @@ def calculate_checksum(self) -> int:
         return checksum
 
 
-class PZN8(PZN7):
+class PZN8(PZN7[T_Output]):
     """Will be fully added in v0.9."""
 
     digits = 7
 
 
-class Code128(Barcode):
+class Code128(Barcode[T_Output]):
     """Initializes a new Code128 instance. The checksum is added automatically
     when building the bars.
 
@@ -152,12 +175,17 @@ class Code128(Barcode):
     name = "Code 128"
     _charset: Literal["A", "B", "C"]
     code: str
-    writer: BaseWriter
     buffer: str
 
-    def __init__(self, code: str, writer: BaseWriter | None = None) -> None:
+    @overload
+    def __init__(self, code: str, writer: None = None) -> None: ...
+
+    @overload
+    def __init__(self, code: str, writer: BaseWriter[T_Output]) -> None: ...
+
+    def __init__(self, code: str, writer: BaseWriter[T_Output] | None = None) -> None:
         self.code = code
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
         self._charset = "C"
         self._digit_buffer = ""  # Accumulate pairs of digits for charset C
         check_code(self.code, self.name, code128.ALL)
@@ -322,13 +350,13 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         options = {"module_width": MIN_SIZE, "quiet_zone": MIN_QUIET_ZONE}
         options.update(writer_options or {})
         return super().render(options, text)
 
 
-class Gs1_128(Code128):  # noqa: N801
+class Gs1_128(Code128[T_Output]):  # noqa: N801
     """
     following the norm, a gs1-128 barcode is a subset of code 128 barcode,
     it can be generated by prepending the code with the FNC1 character
@@ -340,7 +368,13 @@ class Gs1_128(Code128):  # noqa: N801
 
     FNC1_CHAR = "\xf1"
 
-    def __init__(self, code: str, writer: BaseWriter | None = None) -> None:
+    @overload
+    def __init__(self, code: str, writer: None = None) -> None: ...
+
+    @overload
+    def __init__(self, code: str, writer: BaseWriter[T_Output]) -> None: ...
+
+    def __init__(self, code: str, writer: BaseWriter[T_Output] | None = None) -> None:
         code = self.FNC1_CHAR + code
         super().__init__(code, writer)
 
diff --git a/barcode/ean.py b/barcode/ean.py
index 85a4e4a..11265c0 100644
--- a/barcode/ean.py
+++ b/barcode/ean.py
@@ -8,16 +8,16 @@
 __docformat__ = "restructuredtext en"
 
 from typing import TYPE_CHECKING
+from typing import overload
 
 from barcode.base import Barcode
 from barcode.charsets import ean as _ean
 from barcode.errors import IllegalCharacterError
 from barcode.errors import NumberOfDigitsError
 from barcode.errors import WrongCountryCodeError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
-    from PIL.Image import Image as T_Image
-
     from barcode.writer import BaseWriter
 
 # EAN13 Specs (all sizes in mm)
@@ -35,7 +35,7 @@
 }
 
 
-class EuropeanArticleNumber13(Barcode):
+class EuropeanArticleNumber13(Barcode[T_Output]):
     """Initializes EAN13 object.
 
     :param ean: The ean number as string. If the value is too long, it is trimmed.
@@ -47,10 +47,28 @@ class EuropeanArticleNumber13(Barcode):
 
     digits = 12
 
+    @overload
+    def __init__(
+        self,
+        ean: str,
+        writer: None = None,
+        no_checksum: bool = False,
+        guardbar: bool = False,
+    ) -> None: ...
+
+    @overload
     def __init__(
         self,
         ean: str,
-        writer: BaseWriter | None = None,
+        writer: BaseWriter[T_Output],
+        no_checksum: bool = False,
+        guardbar: bool = False,
+    ) -> None: ...
+
+    def __init__(
+        self,
+        ean: str,
+        writer: BaseWriter[T_Output] | None = None,
         no_checksum: bool = False,
         guardbar: bool = False,
     ) -> None:
@@ -81,7 +99,7 @@ def __init__(
         else:
             self.EDGE = _ean.EDGE
             self.MIDDLE = _ean.MIDDLE
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
 
     def __str__(self) -> str:
         return self.ean
@@ -135,28 +153,46 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         options = {"module_width": SIZES["SC2"]}
         options.update(writer_options or {})
         return super().render(options, text)
 
 
-class EuropeanArticleNumber13WithGuard(EuropeanArticleNumber13):
+class EuropeanArticleNumber13WithGuard(EuropeanArticleNumber13[T_Output]):
     """A shortcut to EAN-13 with ``guardbar=True``."""
 
     name = "EAN-13 with guards"
 
+    @overload
+    def __init__(
+        self,
+        ean: str,
+        writer: None = None,
+        no_checksum: bool = False,
+        guardbar: bool = True,
+    ) -> None: ...
+
+    @overload
     def __init__(
         self,
         ean: str,
-        writer: BaseWriter | None = None,
+        writer: BaseWriter[T_Output],
+        no_checksum: bool = False,
+        guardbar: bool = True,
+    ) -> None: ...
+
+    def __init__(
+        self,
+        ean: str,
+        writer: BaseWriter[T_Output] | None = None,
         no_checksum: bool = False,
         guardbar: bool = True,
     ) -> None:
         super().__init__(ean, writer, no_checksum, guardbar)
 
 
-class JapanArticleNumber(EuropeanArticleNumber13):
+class JapanArticleNumber(EuropeanArticleNumber13[T_Output]):
     """Initializes JAN barcode.
 
     :param jan: The jan number as string.
@@ -175,7 +211,7 @@ def __init__(self, jan: str, *args, **kwargs) -> None:
         super().__init__(jan, *args, **kwargs)
 
 
-class EuropeanArticleNumber8(EuropeanArticleNumber13):
+class EuropeanArticleNumber8(EuropeanArticleNumber13[T_Output]):
     """Represents an EAN-8 barcode. See EAN13's __init__ for details.
 
     :param ean: The ean number as string.
@@ -206,22 +242,40 @@ def get_fullcode(self) -> str:
         return self.ean
 
 
-class EuropeanArticleNumber8WithGuard(EuropeanArticleNumber8):
+class EuropeanArticleNumber8WithGuard(EuropeanArticleNumber8[T_Output]):
     """A shortcut to EAN-8 with ``guardbar=True``."""
 
     name = "EAN-8 with guards"
 
+    @overload
+    def __init__(
+        self,
+        ean: str,
+        writer: None = None,
+        no_checksum: bool = False,
+        guardbar: bool = True,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        ean: str,
+        writer: BaseWriter[T_Output],
+        no_checksum: bool = False,
+        guardbar: bool = True,
+    ) -> None: ...
+
     def __init__(
         self,
         ean: str,
-        writer: BaseWriter | None = None,
+        writer: BaseWriter[T_Output] | None = None,
         no_checksum: bool = False,
         guardbar: bool = True,
     ) -> None:
         super().__init__(ean, writer, no_checksum, guardbar)
 
 
-class EuropeanArticleNumber14(EuropeanArticleNumber13):
+class EuropeanArticleNumber14(EuropeanArticleNumber13[T_Output]):
     """Represents an EAN-14 barcode. See EAN13's __init__ for details.
 
     :param ean: The ean number as string.
diff --git a/barcode/isxn.py b/barcode/isxn.py
index 9405519..e739188 100644
--- a/barcode/isxn.py
+++ b/barcode/isxn.py
@@ -25,10 +25,12 @@
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
+from typing import overload
 
 from barcode.ean import EuropeanArticleNumber13
 from barcode.errors import BarcodeError
 from barcode.errors import WrongCountryCodeError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
     from barcode.writer import BaseWriter
@@ -36,7 +38,7 @@
 __docformat__ = "restructuredtext en"
 
 
-class InternationalStandardBookNumber13(EuropeanArticleNumber13):
+class InternationalStandardBookNumber13(EuropeanArticleNumber13[T_Output]):
     """Initializes new ISBN-13 barcode.
 
     :param isbn: The isbn number as string.
@@ -45,10 +47,28 @@ class InternationalStandardBookNumber13(EuropeanArticleNumber13):
 
     name = "ISBN-13"
 
+    @overload
     def __init__(
         self,
         isbn: str,
-        writer: BaseWriter | None = None,
+        writer: None = None,
+        no_checksum: bool = False,
+        guardbar: bool = False,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        isbn: str,
+        writer: BaseWriter[T_Output],
+        no_checksum: bool = False,
+        guardbar: bool = False,
+    ) -> None: ...
+
+    def __init__(
+        self,
+        isbn: str,
+        writer: BaseWriter[T_Output] | None = None,
         no_checksum: bool = False,
         guardbar: bool = False,
     ) -> None:
@@ -61,7 +81,7 @@ def __init__(
         super().__init__(isbn, writer, no_checksum, guardbar)
 
 
-class InternationalStandardBookNumber10(InternationalStandardBookNumber13):
+class InternationalStandardBookNumber10(InternationalStandardBookNumber13[T_Output]):
     """Initializes new ISBN-10 barcode. This code is rendered as EAN-13 by
     prefixing it with 978.
 
@@ -73,7 +93,13 @@ class InternationalStandardBookNumber10(InternationalStandardBookNumber13):
 
     isbn_digits = 9
 
-    def __init__(self, isbn: str, writer: BaseWriter | None = None) -> None:
+    @overload
+    def __init__(self, isbn: str, writer: None = None) -> None: ...
+
+    @overload
+    def __init__(self, isbn: str, writer: BaseWriter[T_Output]) -> None: ...
+
+    def __init__(self, isbn: str, writer: BaseWriter[T_Output] | None = None) -> None:
         isbn = isbn.replace("-", "")
         isbn = isbn[: self.isbn_digits]
         super().__init__("978" + isbn, writer)
@@ -91,7 +117,7 @@ def __str__(self) -> str:
         return self.isbn10
 
 
-class InternationalStandardSerialNumber(EuropeanArticleNumber13):
+class InternationalStandardSerialNumber(EuropeanArticleNumber13[T_Output]):
     """Initializes new ISSN barcode. This code is rendered as EAN-13
     by prefixing it with 977 and adding 00 between code and checksum.
 
@@ -103,7 +129,13 @@ class InternationalStandardSerialNumber(EuropeanArticleNumber13):
 
     issn_digits = 7
 
-    def __init__(self, issn: str, writer: BaseWriter | None = None) -> None:
+    @overload
+    def __init__(self, issn: str, writer: None = None) -> None: ...
+
+    @overload
+    def __init__(self, issn: str, writer: BaseWriter[T_Output]) -> None: ...
+
+    def __init__(self, issn: str, writer: BaseWriter[T_Output] | None = None) -> None:
         issn = issn.replace("-", "")
         issn = issn[: self.issn_digits]
         self.issn = issn
diff --git a/barcode/itf.py b/barcode/itf.py
index 0bb0a0a..0980208 100644
--- a/barcode/itf.py
+++ b/barcode/itf.py
@@ -8,21 +8,21 @@
 __docformat__ = "restructuredtext en"
 
 from typing import TYPE_CHECKING
+from typing import overload
 
 from barcode.base import Barcode
 from barcode.charsets import itf
 from barcode.errors import IllegalCharacterError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
-    from PIL.Image import Image as T_Image
-
     from barcode.writer import BaseWriter
 
 MIN_SIZE = 0.2
 MIN_QUIET_ZONE = 6.4
 
 
-class ITF(Barcode):
+class ITF(Barcode[T_Output]):
     """Initializes a new ITF instance.
 
     :param code: ITF (Interleaved 2 of 5) numeric string
@@ -34,10 +34,28 @@ class ITF(Barcode):
 
     name = "ITF"
 
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: None = None,
+        narrow: int = 2,
+        wide: int = 5,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        code: str,
+        writer: BaseWriter[T_Output],
+        narrow: int = 2,
+        wide: int = 5,
+    ) -> None: ...
+
     def __init__(
         self,
         code: str,
-        writer: BaseWriter | None = None,
+        writer: BaseWriter[T_Output] | None = None,
         narrow: int = 2,
         wide: int = 5,
     ) -> None:
@@ -47,7 +65,7 @@ def __init__(
         if len(code) % 2 != 0:
             code = "0" + code
         self.code = code
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
         self.narrow = narrow
         self.wide = wide
 
@@ -82,7 +100,7 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         options = {
             "module_width": MIN_SIZE / self.narrow,
             "quiet_zone": MIN_QUIET_ZONE,
diff --git a/barcode/py.typed b/barcode/py.typed
new file mode 100644
index 0000000..e69de29
diff --git a/barcode/pybarcode.py b/barcode/pybarcode.py
index 7b233d2..ca326fc 100644
--- a/barcode/pybarcode.py
+++ b/barcode/pybarcode.py
@@ -3,6 +3,7 @@
 import os
 from argparse import ArgumentParser
 from argparse import Namespace
+from typing import Any
 
 import barcode
 from barcode.version import version
@@ -38,7 +39,7 @@ def create_barcode(args: Namespace, parser: ArgumentParser) -> None:
     if args.type != "SVG":
         assert ImageWriter is not None
         opts = {"format": args.type}
-        writer: BaseWriter = ImageWriter()
+        writer: BaseWriter[Any] = ImageWriter()
     else:
         opts = {"compress": args.compress}
         writer = SVGWriter()
diff --git a/barcode/upc.py b/barcode/upc.py
index 42938d5..4d574cc 100644
--- a/barcode/upc.py
+++ b/barcode/upc.py
@@ -9,19 +9,19 @@
 
 from functools import reduce
 from typing import TYPE_CHECKING
+from typing import overload
 
 from barcode.base import Barcode
 from barcode.charsets import upc as _upc
 from barcode.errors import IllegalCharacterError
 from barcode.errors import NumberOfDigitsError
+from barcode.writer import T_Output
 
 if TYPE_CHECKING:
-    from PIL.Image import Image as T_Image
-
     from barcode.writer import BaseWriter
 
 
-class UniversalProductCodeA(Barcode):
+class UniversalProductCodeA(Barcode[T_Output]):
     """Universal Product Code (UPC) barcode.
 
     UPC-A consists of 12 numeric digits.
@@ -31,10 +31,26 @@ class UniversalProductCodeA(Barcode):
 
     digits = 11
 
+    @overload
+    def __init__(
+        self,
+        upc: str,
+        writer: None = None,
+        make_ean: bool = False,
+    ) -> None: ...
+
+    @overload
+    def __init__(
+        self,
+        upc: str,
+        writer: BaseWriter[T_Output],
+        make_ean: bool = False,
+    ) -> None: ...
+
     def __init__(
         self,
         upc: str,
-        writer: BaseWriter | None = None,
+        writer: BaseWriter[T_Output] | None = None,
         make_ean: bool = False,
     ) -> None:
         """Initializes new UPC-A barcode.
@@ -56,7 +72,7 @@ def __init__(
             )
         self.upc = upc
         self.upc = f"{upc}{self.calculate_checksum()}"
-        self.writer = writer or self.default_writer()
+        self.writer = self._resolve_writer(writer)
 
     def __str__(self) -> str:
         if self.ean:
@@ -77,12 +93,12 @@ def calculate_checksum(self) -> int:
         :rtype: int
         """
 
-        def sum_(x: str, y: str) -> int:
-            return int(x) + int(y)
+        def sum_(x: int, y: str) -> int:
+            return x + int(y)
 
         upc = self.upc[0 : self.digits]
-        oddsum = reduce(sum_, upc[::2])
-        evensum = reduce(sum_, upc[1::2])
+        oddsum = reduce(sum_, upc[::2], 0)
+        evensum = reduce(sum_, upc[1::2], 0)
         check = (evensum + oddsum * 3) % 10
         if check == 0:
             return 0
@@ -125,7 +141,7 @@ def render(
         self,
         writer_options: dict | None = None,
         text: str | None = None,
-    ) -> bytes | T_Image:
+    ) -> T_Output:
         options = {"module_width": 0.33}
         options.update(writer_options or {})
         return super().render(options, text)
diff --git a/barcode/writer.py b/barcode/writer.py
index ca8a02d..114e344 100644
--- a/barcode/writer.py
+++ b/barcode/writer.py
@@ -5,6 +5,7 @@
 import xml.dom.minidom
 from typing import TYPE_CHECKING
 from typing import BinaryIO
+from typing import Generic
 from typing import TypedDict
 
 from barcode.version import version
@@ -78,8 +79,20 @@ def create_svg_object(with_doctype: bool = False) -> xml.dom.minidom.Document:
 COMMENT = f"Autogenerated with python-barcode {version}"
 PATH = os.path.dirname(os.path.abspath(__file__))
 
+if TYPE_CHECKING:
+    # Typevar defaults (PEP 696) only exist at runtime on Python 3.13+, so use
+    # the typing_extensions variant for type-checkers only; this way it is not
+    # a runtime dependency.
+    from typing_extensions import TypeVar
+
+    T_Output = TypeVar("T_Output", default=bytes)
+else:
+    from typing import TypeVar
+
+    T_Output = TypeVar("T_Output")
+
 
-class BaseWriter:
+class BaseWriter(Generic[T_Output]):
     """Baseclass for all writers.
 
     Initializes the basic writer options. Child classes can add more attributes and can
@@ -164,7 +177,7 @@ def calculate_size(self, modules_per_line: int, number_of_lines: int) -> tuple:
             height += self.text_line_distance * (number_of_text_lines - 1)
         return width, height
 
-    def save(self, filename: str, output: bytes | T_Image) -> str:
+    def save(self, filename: str, output: T_Output) -> str:
         """Saves the rendered output to `filename`.
 
         :param filename: Filename without extension.
@@ -222,7 +235,7 @@ def packed(self, line: str) -> Generator[tuple[int, float], str, None]:
                     yield (-c, self.guard_height_factor)
                 c = 1
 
-    def render(self, code: list[str]) -> bytes | T_Image:
+    def render(self, code: list[str]) -> T_Output:
         """Renders the barcode to whatever the inheriting writer provides,
         using the registered callbacks.
 
@@ -305,11 +318,11 @@ def render(self, code: list[str]) -> bytes | T_Image:
 
         return self._callbacks["finish"]()
 
-    def write(self, content: bytes | T_Image, fp: BinaryIO) -> None:
+    def write(self, content: T_Output, fp: BinaryIO) -> None:
         raise NotImplementedError
 
 
-class SVGWriter(BaseWriter):
+class SVGWriter(BaseWriter[bytes]):
     def __init__(self) -> None:
         super().__init__(
             self._init,
@@ -423,10 +436,27 @@ def write(self, content: bytes, fp: BinaryIO) -> None:
 
 
 if Image is None:
-    ImageWriter: type | None = None
+    if TYPE_CHECKING:
+        # Keep this stub's signatures in sync with the real class below. It
+        # exists so that type-checkers see a single, always-defined class
+        # regardless of whether Pillow is installed.
+
+        class ImageWriter(BaseWriter["T_Image"]):
+            def __init__(
+                self,
+                format: str = "PNG",
+                mode: str = "RGB",
+                dpi: int = 300,
+            ) -> None: ...
+
+            def save(self, filename: str, output: T_Image) -> str: ...
+
+            def write(self, content: T_Image, fp: BinaryIO) -> None: ...
+    else:
+        ImageWriter = None
 else:
 
-    class ImageWriter(BaseWriter):  # type: ignore[no-redef]
+    class ImageWriter(BaseWriter["T_Image"]):  # type: ignore[no-redef]
         format: str
         mode: str
         dpi: int
diff --git a/docs/changelog.rst b/docs/changelog.rst
index 9a15b52..56266c6 100644
--- a/docs/changelog.rst
+++ b/docs/changelog.rst
@@ -9,6 +9,8 @@ v0.17.0
   barcodes. (#251)
 * Fix ISBN-10 and ISSN barcodes being truncated to 10 and 8 digits.
 * Fix Code128 emitting different (but valid) output depending on invocation.
+* Add type annotations for writers and barcode classes. Both are now generic
+  over the writer's output type, and the package ships a ``py.typed`` marker.
 
 v0.16.1
 ~~~~~~~
diff --git a/pyproject.toml b/pyproject.toml
index 13cc895..f903a36 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,12 +42,17 @@ issues = "https://github.com/WhyNotHugo/python-barcode/issues"
 funding= "https://whynothugo.nl/sponsor/"
 
 [tool.setuptools.package-data]
-barcode = ["barcode/fonts/*.ttf"]
+barcode = ["barcode/fonts/*.ttf", "py.typed"]
 
 [tool.setuptools_scm]
 write_to = "barcode/version.py"
 version_scheme = "post-release"
 
+# Pillow is an optional dependency; the plain mypy environment runs without it.
+[[tool.mypy.overrides]]
+module = "PIL.*"
+ignore_missing_imports = true
+
 [tool.ruff.lint]
 extend-select = [
     "ANN",
diff --git a/tests/test_builds.py b/tests/test_builds.py
index fb56c23..396f1e9 100644
--- a/tests/test_builds.py
+++ b/tests/test_builds.py
@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from barcode import get_barcode
+from barcode.codex import Code128
 
 
 def test_ean8_builds() -> None:
@@ -32,7 +33,7 @@ def test_code128_leading_99_not_stripped() -> None:
     # number 99, which collided with the TO_C switch marker. ``_try_to_optimize``
     # therefore folded it away, silently dropping the leading "99" from the
     # barcode (e.g. "9912345678" was encoded as "12345678").
-    bc = get_barcode("code128", "9912345678")
+    bc = Code128("9912345678")
     assert bc.encoded == [_START_C, 99, 12, 34, 56, 78]
     assert _decode_code128_c(bc.encoded) == "9912345678"
 
@@ -41,7 +42,7 @@ def test_code128_other_leading_pairs_unaffected() -> None:
     # Pairs whose code number does not collide with a switch code always worked
     # and must keep working.
     for code, first_pair in (("0012345678", 0), ("1212345678", 12)):
-        bc = get_barcode("code128", code)
+        bc = Code128(code)
         assert bc.encoded[:2] == [_START_C, first_pair]
         assert _decode_code128_c(bc.encoded) == code
 
@@ -49,4 +50,4 @@ def test_code128_other_leading_pairs_unaffected() -> None:
 def test_code128_start_charset_folding_preserved() -> None:
     # The START-code folding optimisation (START_C + an immediate charset switch
     # collapsed into a single START code) must still apply for genuine switches.
-    assert get_barcode("code128", "Wikipedia").encoded[0] == 104  # START_B
+    assert Code128("Wikipedia").encoded[0] == 104  # START_B
diff --git a/tests/test_writers.py b/tests/test_writers.py
index 27454bb..3515259 100644
--- a/tests/test_writers.py
+++ b/tests/test_writers.py
@@ -2,19 +2,19 @@
 
 import os
 from io import BytesIO
+from typing import assert_type
 
 from barcode import EAN13
+from barcode.writer import Image
 from barcode.writer import ImageWriter
 from barcode.writer import SVGWriter
 
 PATH = os.path.dirname(os.path.abspath(__file__))
 TESTPATH = os.path.join(PATH, "test_outputs")
 
-if ImageWriter is not None:
+if Image is not None:
 
     def test_saving_image_to_byteio() -> None:
-        assert ImageWriter is not None  # workaround for mypy
-
         rv = BytesIO()
         EAN13(str(100000902922), writer=ImageWriter()).write(rv)
 
@@ -22,8 +22,6 @@ def test_saving_image_to_byteio() -> None:
             EAN13("100000011111", writer=ImageWriter()).write(f)
 
     def test_saving_rgba_image() -> None:
-        assert ImageWriter is not None  # workaround for mypy
-
         rv = BytesIO()
         EAN13(str(100000902922), writer=ImageWriter()).write(rv)
 
@@ -34,6 +32,17 @@ def test_saving_rgba_image() -> None:
                 f, options={"background": "rgba(255,0,0,0)"}
             )
 
+    def test_none_writer_typed_as_bytes_or_image() -> None:
+        writer: ImageWriter | None = None
+        bc = EAN13("100000011111", writer=writer)
+        assert_type(bc, EAN13[bytes] | EAN13[Image.Image])
+
+else:
+
+    def test_none_writer_typed_as_bytes() -> None:
+        bc = EAN13("100000011111", writer=None)
+        assert_type(bc, EAN13[bytes])
+
 
 def test_saving_svg_to_byteio() -> None:
     rv = BytesIO()
@@ -49,3 +58,12 @@ def test_saving_svg_to_byteio_with_guardbar() -> None:
 
     with open(f"{TESTPATH}/somefile_guardbar.svg", "wb") as f:
         EAN13("100000011111", writer=SVGWriter(), guardbar=True).write(f)
+
+
+def test_none_writer_defaults_to_svg_writer() -> None:
+    # A None writer, even when statically typed as an image writer,
+    # still falls back to the default SVG writer at runtime.
+    writer: ImageWriter | None = None
+    bc = EAN13("100000011111", writer=writer)
+    assert isinstance(bc.writer, SVGWriter)
+    assert isinstance(bc.render(), bytes)
diff --git a/tox.ini b/tox.ini
index ba2c87a..f7165eb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,6 +13,14 @@ usedevelop = True
 [testenv:mypy]
 deps =
   mypy
-  images: Pillow
+  pytest
+commands = mypy .
+usedevelop = True
+
+[testenv:mypy-images]
+deps =
+  mypy
+  pytest
+  Pillow
 commands = mypy .
 usedevelop = True