diff --git a/.github/workflows/release-python.yml b/.github/workflows/release-python.yml
index c2ccec6..9de5690 100644
--- a/.github/workflows/release-python.yml
+++ b/.github/workflows/release-python.yml
@@ -62,5 +62,3 @@ jobs:
         path: dist/
     - name: Publish distribution 📦 to PyPI
       uses: pypa/gh-action-pypi-publish@release/v1
-      with:
-        repository-url: https://test.pypi.org/legacy/
diff --git a/.github/workflows/test-python.yml b/.github/workflows/test-python.yml
new file mode 100644
index 0000000..1e2c168
--- /dev/null
+++ b/.github/workflows/test-python.yml
@@ -0,0 +1,65 @@
+name: Python Tests
+
+on:
+  push:
+      branches: ["main"]
+  pull_request:
+
+concurrency:
+  group: tests-${{ github.ref }}
+  cancel-in-progress: true
+
+defaults:
+  run:
+    shell: bash -eux {0}
+
+env:
+  MONGODB_VERSION: "7.0"
+
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: ["ubuntu-latest", "macos-latest", "windows-latest"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+      fail-fast: false
+    name: CPython ${{ matrix.python-version }}-${{ matrix.os }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+          fetch-depth: 0
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Start MongoDB on Linux
+        if: ${{ startsWith(runner.os, 'Linux') }}
+        run: |
+            docker run --name mongodb -p 27017:27017 -e MONGO_INITDB_DATABASE=unittest --detach mongo:${MONGODB_VERSION} mongod --replSet rs --setParameter transactionLifetimeLimitSeconds=5
+            until docker exec --tty mongodb mongosh 127.0.0.1:27017 --eval "db.runCommand({ ping: 1 })"; do
+              sleep 1
+            done
+            sudo docker exec --tty mongodb mongosh 127.0.0.1:27017 --eval "rs.initiate({\"_id\":\"rs\",\"members\":[{\"_id\":0,\"host\":\"127.0.0.1:27017\" }]})"
+      - name: Start MongoDB on MacOS
+        if: ${{ startsWith(runner.os, 'macOS') }}
+        run: |
+          brew tap mongodb/brew
+          brew install mongodb/brew/mongodb-community@${MONGODB_VERSION}
+          brew services start mongodb-community@${MONGODB_VERSION}
+      - name: Start MongoDB on Windows
+        if: ${{ startsWith(runner.os, 'Windows') }}
+        shell: powershell
+        run: |
+          mkdir data
+          mongod --remove
+          mongod --install --dbpath=$(pwd)/data --logpath=$PWD/mongo.log
+          net start MongoDB
+      - name: Install package and pytest
+        run: |
+          python -m pip install .
+          python -m pip install pytest
+      - name: Run the tests
+        run: |
+          pytest .
\ No newline at end of file
diff --git a/.github/workflows/zizmor.yml b/.github/workflows/zizmor.yml
new file mode 100644
index 0000000..0fbdbd6
--- /dev/null
+++ b/.github/workflows/zizmor.yml
@@ -0,0 +1,32 @@
+name: GitHub Actions Security Analysis with zizmor
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  zizmor:
+    name: zizmor latest via Cargo
+    runs-on: ubuntu-latest
+    permissions:
+      security-events: write
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - name: Setup Rust
+        uses: actions-rust-lang/setup-rust-toolchain@v1
+      - name: Get zizmor
+        run: cargo install zizmor
+      - name: Run zizmor
+        run: zizmor --format sarif . > results.sarif
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+      - name: Upload SARIF file
+        uses: github/codeql-action/upload-sarif@v3
+        with:
+          sarif_file: results.sarif
+          category: zizmor
diff --git a/README.md b/README.md
index 2ea4f8f..da9b637 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # Flask-PyMongo
 
-PyMongo support for Flask applications
+PyMongo support for Flask applications.   Requires `flask>=3.0` and `pymongo>=4.0`
 
 ## Quickstart
 
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
deleted file mode 100644
index f4826ce..0000000
--- a/azure-pipelines.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-jobs:
-- job: 'Style'
-  pool:
-    vmImage: 'ubuntu-latest'
-  steps:
-  - task: UsePythonVersion@0
-    inputs:
-      versionSpec: '3.9'
-      architecture: 'x64'
-  - script: |
-      pip install tox
-      tox -e style
-    displayName: 'tox -e style'
-
-- job: 'Test'
-  pool:
-    vmImage: 'ubuntu-latest'
-  strategy:
-    matrix:
-      Python38:
-        python.version: '3.8'
-      Python39:
-        python.version: '3.9'
-      Python310:
-        python.version: '3.10'
-      Python311:
-        python.version: '3.11'
-    maxParallel: 4
-
-  steps:
-  - task: UsePythonVersion@0
-    inputs:
-      versionSpec: '$(python.version)'
-      architecture: 'x64'
-
-  - script: |
-      pip install wheel
-      pip install tox tox-docker
-      tox
-    displayName: 'tox'
diff --git a/flask_pymongo/__init__.py b/flask_pymongo/__init__.py
index 974202d..892649c 100644
--- a/flask_pymongo/__init__.py
+++ b/flask_pymongo/__init__.py
@@ -28,6 +28,7 @@
 
 from functools import partial
 from mimetypes import guess_type
+import hashlib
 
 from flask import abort, current_app, request
 from gridfs import GridFS, NoFile
@@ -41,7 +42,7 @@
     DriverInfo = None
 
 from flask_pymongo._version import __version__
-from flask_pymongo.helpers import BSONObjectIdConverter, JSONEncoder
+from flask_pymongo.helpers import BSONObjectIdConverter, BSONProvider
 from flask_pymongo.wrappers import MongoClient
 
 DESCENDING = pymongo.DESCENDING
@@ -65,10 +66,10 @@ class PyMongo(object):
 
     """
 
-    def __init__(self, app=None, uri=None, json_options=None, *args, **kwargs):
+    def __init__(self, app=None, uri=None,  *args, **kwargs):
         self.cx = None
         self.db = None
-        self._json_encoder = partial(JSONEncoder, json_options=json_options)
+        self._json_provider = BSONProvider(app)
 
         if app is not None:
             self.init_app(app, uri, *args, **kwargs)
@@ -122,7 +123,7 @@ def init_app(self, app, uri=None, *args, **kwargs):
             self.db = self.cx[database_name]
 
         app.url_map.converters["ObjectId"] = BSONObjectIdConverter
-        app.json_encoder = self._json_encoder
+        app.json = self._json_provider
 
     # view helpers
     def send_file(self, filename, base="fs", version=-1, cache_for=31536000):
@@ -163,14 +164,20 @@ def get_upload(filename):
         # mostly copied from flask/helpers.py, with
         # modifications for GridFS
         data = wrap_file(request.environ, fileobj, buffer_size=1024 * 255)
+        content_type, _ = guess_type(filename)
         response = current_app.response_class(
             data,
-            mimetype=fileobj.content_type,
+            mimetype=content_type,
             direct_passthrough=True,
         )
         response.content_length = fileobj.length
         response.last_modified = fileobj.upload_date
-        response.set_etag(fileobj.md5)
+        # Compute the sha1 sum of the file for the etag.
+        pos = fileobj.tell()
+        raw_data = fileobj.read()
+        fileobj.seek(pos)
+        digest = hashlib.sha1(raw_data).hexdigest()
+        response.set_etag(digest)
         response.cache_control.max_age = cache_for
         response.cache_control.public = True
         response.make_conditional(request)
diff --git a/flask_pymongo/helpers.py b/flask_pymongo/helpers.py
index 617b6ed..8cdda23 100644
--- a/flask_pymongo/helpers.py
+++ b/flask_pymongo/helpers.py
@@ -24,21 +24,16 @@
 # POSSIBILITY OF SUCH DAMAGE.
 
 
-__all__ = ("BSONObjectIdConverter", "JSONEncoder")
+__all__ = ("BSONObjectIdConverter", "BSONProvider")
 
-from bson import json_util, SON
+from bson import json_util
 from bson.errors import InvalidId
 from bson.objectid import ObjectId
-from flask import abort, json as flask_json
-from six import iteritems, string_types
+from flask import abort
+from flask.json.provider import JSONProvider
 from werkzeug.routing import BaseConverter
 import pymongo
-
-if pymongo.version_tuple >= (3, 5, 0):
-    from bson.json_util import RELAXED_JSON_OPTIONS
-    DEFAULT_JSON_OPTIONS = RELAXED_JSON_OPTIONS
-else:
-    DEFAULT_JSON_OPTIONS = None
+from bson.json_util import RELAXED_JSON_OPTIONS
 
 
 def _iteritems(obj):
@@ -83,7 +78,7 @@ def to_url(self, value):
         return str(value)
 
 
-class JSONEncoder(flask_json.JSONEncoder):
+class BSONProvider(JSONProvider):
 
     """A JSON encoder that uses :mod:`bson.json_util` for MongoDB documents.
 
@@ -101,54 +96,23 @@ def json_route(cart_id):
     differently than you expect. See :class:`~bson.json_util.JSONOptions`
     for details on the particular serialization that will be used.
 
-    A :class:`~flask_pymongo.helpers.JSONEncoder` is automatically
+    A :class:`~flask_pymongo.helpers.JSONProvider` is automatically
     automatically installed on the :class:`~flask_pymongo.PyMongo`
     instance at creation time, using
-    :const:`~bson.json_util.RELAXED_JSON_OPTIONS`. You can change the
-    :class:`~bson.json_util.JSONOptions` in use by passing
-    ``json_options`` to the :class:`~flask_pymongo.PyMongo`
-    constructor.
-
-    .. note::
-
-        :class:`~bson.json_util.JSONOptions` is only supported as of
-        PyMongo version 3.4. For older versions of PyMongo, you will
-        have less control over the JSON format that results from calls
-        to :func:`~flask.json.jsonify`.
-
-    .. versionadded:: 2.4.0
-
+    :const:`~bson.json_util.RELAXED_JSON_OPTIONS`. 
     """
 
-    def __init__(self, json_options, *args, **kwargs):
-        if json_options is None:
-            json_options = DEFAULT_JSON_OPTIONS
-        if json_options is not None:
-            self._default_kwargs = {"json_options": json_options}
-        else:
-            self._default_kwargs = {}
+    def __init__(self, app):
+        self._default_kwargs = {"json_options": RELAXED_JSON_OPTIONS}
 
-        super(JSONEncoder, self).__init__(*args, **kwargs)
+        super().__init__(app)
 
-    def default(self, obj):
+    def dumps(self, obj):
         """Serialize MongoDB object types using :mod:`bson.json_util`.
+        """
+        return json_util.dumps(obj)
 
-        Falls back to Flask's default JSON serialization for all other types.
-
-        This may raise ``TypeError`` for object types not recognized.
-
-        .. versionadded:: 2.4.0
-
+    def loads(self, str_obj):
+        """Deserialize MongoDB object types using :mod:`bson.json_util`.
         """
-        if hasattr(obj, "iteritems") or hasattr(obj, "items"):
-            return SON((k, self.default(v)) for k, v in iteritems(obj))
-        elif hasattr(obj, "__iter__") and not isinstance(obj, string_types):
-            return [self.default(v) for v in obj]
-        else:
-            try:
-                return json_util.default(obj, **self._default_kwargs)
-            except TypeError:
-                # PyMongo couldn't convert into a serializable object, and
-                # the Flask default JSONEncoder won't; so we return the
-                # object itself and let stdlib json handle it if possible
-                return obj
+        return json_util.loads(str_obj)
\ No newline at end of file
diff --git a/flask_pymongo/tests/test_config.py b/flask_pymongo/tests/test_config.py
index 9da8914..f2f5e5e 100644
--- a/flask_pymongo/tests/test_config.py
+++ b/flask_pymongo/tests/test_config.py
@@ -44,7 +44,7 @@ def test_config_with_uri_in_flask_conf_var(self):
 
         _wait_until_connected(mongo)
         assert mongo.db.name == self.dbname
-        assert ("localhost", self.port) == mongo.cx.address
+        assert ("localhost", self.port) == mongo.cx.address or ("127.0.0.1", self.port) == mongo.cx.address
 
     def test_config_with_uri_passed_directly(self):
         uri = "mongodb://localhost:{}/{}".format(self.port, self.dbname)
@@ -53,7 +53,7 @@ def test_config_with_uri_passed_directly(self):
 
         _wait_until_connected(mongo)
         assert mongo.db.name == self.dbname
-        assert ("localhost", self.port) == mongo.cx.address
+        assert ("localhost", self.port) == mongo.cx.address or ("127.0.0.1", self.port) == mongo.cx.address
 
     def test_it_fails_with_no_uri(self):
         self.app.config.pop("MONGO_URI", None)
diff --git a/flask_pymongo/tests/test_gridfs.py b/flask_pymongo/tests/test_gridfs.py
index 5dc57da..ff742c5 100644
--- a/flask_pymongo/tests/test_gridfs.py
+++ b/flask_pymongo/tests/test_gridfs.py
@@ -1,4 +1,4 @@
-from hashlib import md5
+from hashlib import sha1
 from io import BytesIO
 
 from bson.objectid import ObjectId
@@ -30,15 +30,6 @@ def test_it_saves_files(self):
         gridfs = GridFS(self.mongo.db)
         assert gridfs.exists({"filename": "my-file"})
 
-    def test_it_guesses_type_from_filename(self):
-        fileobj = BytesIO(b"these are the bytes")
-
-        self.mongo.save_file("my-file.txt", fileobj)
-
-        gridfs = GridFS(self.mongo.db)
-        gridfile = gridfs.find_one({"filename": "my-file.txt"})
-        assert gridfile.content_type == "text/plain"
-
     def test_it_saves_files_with_props(self):
         fileobj = BytesIO(b"these are the bytes")
 
@@ -82,7 +73,7 @@ def test_it_sets_supports_conditional_gets(self):
         environ_args = {
             "method": "GET",
             "headers": {
-                "If-None-Match": md5(self.myfile.getvalue()).hexdigest(),
+                "If-None-Match": sha1(self.myfile.getvalue()).hexdigest(),
             },
         }
 
diff --git a/flask_pymongo/tests/test_json.py b/flask_pymongo/tests/test_json.py
index 93d179d..4f506d9 100644
--- a/flask_pymongo/tests/test_json.py
+++ b/flask_pymongo/tests/test_json.py
@@ -2,7 +2,6 @@
 
 from bson import ObjectId
 from flask import jsonify
-from six import ensure_str
 
 from flask_pymongo.tests.util import FlaskPyMongoTest
 
@@ -11,12 +10,12 @@ class JSONTest(FlaskPyMongoTest):
 
     def test_it_encodes_json(self):
         resp = jsonify({"foo": "bar"})
-        dumped = json.loads(ensure_str(resp.get_data()))
+        dumped = json.loads(resp.get_data().decode('utf-8'))
         self.assertEqual(dumped, {"foo": "bar"})
 
     def test_it_handles_pymongo_types(self):
         resp = jsonify({"id": ObjectId("5cf29abb5167a14c9e6e12c4")})
-        dumped = json.loads(ensure_str(resp.get_data()))
+        dumped = json.loads(resp.get_data().decode('utf-8'))
         self.assertEqual(dumped, {"id": {"$oid": "5cf29abb5167a14c9e6e12c4"}})
 
     def test_it_jsonifies_a_cursor(self):
@@ -25,5 +24,5 @@ def test_it_jsonifies_a_cursor(self):
         curs = self.mongo.db.rows.find(projection={"_id": False}).sort("foo")
 
         resp = jsonify(curs)
-        dumped = json.loads(ensure_str(resp.get_data()))
+        dumped = json.loads(resp.get_data().decode('utf-8'))
         self.assertEqual([{"foo": "bar"}, {"foo": "baz"}], dumped)
diff --git a/flask_pymongo/tests/test_wrappers.py b/flask_pymongo/tests/test_wrappers.py
index 1bb334b..537887f 100644
--- a/flask_pymongo/tests/test_wrappers.py
+++ b/flask_pymongo/tests/test_wrappers.py
@@ -18,16 +18,3 @@ def test_find_one_or_404(self):
         # now it should not raise
         thing = self.mongo.db.things.find_one_or_404({"_id": "thing"})
         assert thing["val"] == "foo", "got wrong thing"
-
-        # also test with dotted-named collections
-        self.mongo.db.things.morethings.delete_many({})
-        try:
-            self.mongo.db.things.morethings.find_one_or_404({"_id": "thing"})
-        except HTTPException as notfound:
-            assert notfound.code == 404, "raised wrong exception"
-
-        self.mongo.db.things.morethings.insert_one({"_id": "thing", "val": "foo"})
-
-        # now it should not raise
-        thing = self.mongo.db.things.morethings.find_one_or_404({"_id": "thing"})
-        assert thing["val"] == "foo", "got wrong thing"
diff --git a/flask_pymongo/tests/util.py b/flask_pymongo/tests/util.py
index a6e7496..b35cd9c 100644
--- a/flask_pymongo/tests/util.py
+++ b/flask_pymongo/tests/util.py
@@ -1,4 +1,3 @@
-import os
 import unittest
 
 import flask
@@ -6,34 +5,8 @@
 import flask_pymongo
 
 
-class ToxDockerMixin(object):
 
-    """
-    Sets :attr:`port` based on the env var from tox-docker, if present.
-    """
-
-    def setUp(self):
-        super(ToxDockerMixin, self).setUp()
-
-        # tox-docker could be running any version; find the env
-        # var that looks like what tox-docker would provide, but
-        # fail if there are more than one
-        env_vars = [
-            (k, v)
-            for k, v in os.environ.items()
-            if k.startswith("MONGO") and k.endswith("_TCP_PORT")
-        ]
-
-        self.port = 27017
-        if len(env_vars) == 1:
-            self.port = int(env_vars[0][1])
-        else:
-            self.fail(
-                f"too many tox-docker mongo port env vars (found {len(env_vars)})",
-            )
-
-
-class FlaskRequestTest(ToxDockerMixin, unittest.TestCase):
+class FlaskRequestTest(unittest.TestCase):
 
     def setUp(self):
         super(FlaskRequestTest, self).setUp()
@@ -42,6 +15,7 @@ def setUp(self):
         self.app = flask.Flask("test")
         self.context = self.app.test_request_context("/")
         self.context.push()
+        self.port = 27017
 
     def tearDown(self):
         super(FlaskRequestTest, self).tearDown()
diff --git a/setup.py b/setup.py
index 539c7d9..4644b25 100644
--- a/setup.py
+++ b/setup.py
@@ -30,9 +30,8 @@
     platforms="any",
     packages=find_packages(),
     install_requires=[
-        "Flask>=1.0",
-        "PyMongo>=3.11",
-        "six",
+        "Flask>=3.0",
+        "PyMongo>=4.0",
     ],
     classifiers=[
         "Environment :: Web Environment",