diff --git a/.github/workflows/test-suite.yml b/.github/workflows/test-suite.yml
index ce3df5db..ae70a6b3 100644
--- a/.github/workflows/test-suite.yml
+++ b/.github/workflows/test-suite.yml
@@ -14,7 +14,7 @@ jobs:
 
     strategy:
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
       - uses: "actions/checkout@v4"
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4f1233ef..ee0f81f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,13 +4,15 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
-## Dev
+## 0.28.1 (6th December, 2024)
 
 * Fix SSL case where `verify=False` together with client side certificates.
  
 ## 0.28.0 (28th November, 2024)
 
-The 0.28 release includes a limited set of deprecations.
+Be aware that the default *JSON request bodies now use a more compact representation*. This is generally considered a prefered style, tho may require updates to test suites.
+
+The 0.28 release includes a limited set of deprecations...
 
 **Deprecations**:
 
diff --git a/docs/advanced/clients.md b/docs/advanced/clients.md
index a55fc596..90969cef 100644
--- a/docs/advanced/clients.md
+++ b/docs/advanced/clients.md
@@ -270,8 +270,9 @@ multipart file encoding is available by passing a dictionary with the
 name of the payloads as keys and either tuple of elements or a file-like object or a string as values.
 
 ```pycon
->>> files = {'upload-file': ('report.xls', open('report.xls', 'rb'), 'application/vnd.ms-excel')}
->>> r = httpx.post("https://httpbin.org/post", files=files)
+>>> with open('report.xls', 'rb') as report_file:
+...     files = {'upload-file': ('report.xls', report_file, 'application/vnd.ms-excel')}
+...     r = httpx.post("https://httpbin.org/post", files=files)
 >>> print(r.text)
 {
   ...
@@ -318,7 +319,10 @@ To do that, pass a list of `(field, <file>)` items instead of a dictionary, allo
 For instance this request sends 2 files, `foo.png` and `bar.png` in one request on the `images` form field:
 
 ```pycon
->>> files = [('images', ('foo.png', open('foo.png', 'rb'), 'image/png')),
-                      ('images', ('bar.png', open('bar.png', 'rb'), 'image/png'))]
->>> r = httpx.post("https://httpbin.org/post", files=files)
+>>> with open('foo.png', 'rb') as foo_file, open('bar.png', 'rb') as bar_file:
+...     files = [
+...         ('images', ('foo.png', foo_file, 'image/png')),
+...         ('images', ('bar.png', bar_file, 'image/png')),
+...     ]
+...     r = httpx.post("https://httpbin.org/post", files=files)
 ```
diff --git a/docs/api.md b/docs/api.md
index d01cc649..f1bd50c9 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -159,3 +159,18 @@ what gets sent over the wire.*
 * `def delete(name, [domain], [path])`
 * `def clear([domain], [path])`
 * *Standard mutable mapping interface*
+
+## `Proxy`
+
+*A configuration of the proxy server.*
+
+```pycon
+>>> proxy = Proxy("http://proxy.example.com:8030")
+>>> client = Client(proxy=proxy)
+```
+
+* `def __init__(url, [ssl_context], [auth], [headers])`
+* `.url` - **URL**
+* `.auth` - **tuple[str, str]**
+* `.headers` - **Headers**
+* `.ssl_context` - **SSLContext**
diff --git a/docs/quickstart.md b/docs/quickstart.md
index aa203a83..38da2fec 100644
--- a/docs/quickstart.md
+++ b/docs/quickstart.md
@@ -174,8 +174,9 @@ Form encoded data can also include multiple values from a given key.
 You can also upload files, using HTTP multipart encoding:
 
 ```pycon
->>> files = {'upload-file': open('report.xls', 'rb')}
->>> r = httpx.post("https://httpbin.org/post", files=files)
+>>> with open('report.xls', 'rb') as report_file:
+...     files = {'upload-file': report_file}
+...     r = httpx.post("https://httpbin.org/post", files=files)
 >>> print(r.text)
 {
   ...
@@ -190,8 +191,9 @@ You can also explicitly set the filename and content type, by using a tuple
 of items for the file value:
 
 ```pycon
->>> files = {'upload-file': ('report.xls', open('report.xls', 'rb'), 'application/vnd.ms-excel')}
->>> r = httpx.post("https://httpbin.org/post", files=files)
+>>> with open('report.xls', 'rb') report_file:
+...     files = {'upload-file': ('report.xls', report_file, 'application/vnd.ms-excel')}
+...     r = httpx.post("https://httpbin.org/post", files=files)
 >>> print(r.text)
 {
   ...
@@ -206,8 +208,9 @@ If you need to include non-file data fields in the multipart form, use the `data
 
 ```pycon
 >>> data = {'message': 'Hello, world!'}
->>> files = {'file': open('report.xls', 'rb')}
->>> r = httpx.post("https://httpbin.org/post", data=data, files=files)
+>>> with open('report.xls', 'rb') as report_file:
+...     files = {'file': report_file}
+...     r = httpx.post("https://httpbin.org/post", data=data, files=files)
 >>> print(r.text)
 {
   ...
diff --git a/docs/third_party_packages.md b/docs/third_party_packages.md
index 78ecc5a7..546607f7 100644
--- a/docs/third_party_packages.md
+++ b/docs/third_party_packages.md
@@ -2,67 +2,21 @@
 
 As HTTPX usage grows, there is an expanding community of developers building tools and libraries that integrate with HTTPX, or depend on HTTPX. Here are some of them.
 
+<!-- NOTE: Entries are alphabetised. -->
+
 ## Plugins
 
-### httpx-ws
-
-[GitHub](https://github.com/frankie567/httpx-ws) - [Documentation](https://frankie567.github.io/httpx-ws/)
-
-WebSocket support for HTTPX.
-
-### httpx-socks
-
-[GitHub](https://github.com/romis2012/httpx-socks)
-
-Proxy (HTTP, SOCKS) transports for httpx.
-
 ### Hishel
 
 [GitHub](https://github.com/karpetrosyan/hishel) - [Documentation](https://hishel.com/)
 
 An elegant HTTP Cache implementation for HTTPX and HTTP Core.
 
-### Authlib
-
-[GitHub](https://github.com/lepture/authlib) - [Documentation](https://docs.authlib.org/en/latest/)
-
-The ultimate Python library in building OAuth and OpenID Connect clients and servers. Includes an [OAuth HTTPX client](https://docs.authlib.org/en/latest/client/httpx.html).
-
-### Gidgethub
-
-[GitHub](https://github.com/brettcannon/gidgethub) - [Documentation](https://gidgethub.readthedocs.io/en/latest/index.html)
-
-An asynchronous GitHub API library. Includes [HTTPX support](https://gidgethub.readthedocs.io/en/latest/httpx.html).
-
 ### HTTPX-Auth
 
 [GitHub](https://github.com/Colin-b/httpx_auth) - [Documentation](https://colin-b.github.io/httpx_auth/)
 
-Provides authentication classes to be used with HTTPX [authentication parameter](advanced/authentication.md#customizing-authentication).
-
-### pytest-HTTPX
-
-[GitHub](https://github.com/Colin-b/pytest_httpx) - [Documentation](https://colin-b.github.io/pytest_httpx/)
-
-Provides `httpx_mock` [pytest](https://docs.pytest.org/en/latest/) fixture to mock HTTPX within test cases.
-
-### RESPX
-
-[GitHub](https://github.com/lundberg/respx) - [Documentation](https://lundberg.github.io/respx/)
-
-A utility for mocking out the Python HTTPX library.
-
-### rpc.py
-
-[Github](https://github.com/abersheeran/rpc.py) - [Documentation](https://github.com/abersheeran/rpc.py#rpcpy)
-
-An fast and powerful RPC framework based on ASGI/WSGI. Use HTTPX as the client of the RPC service.
-
-### VCR.py
-
-[GitHub](https://github.com/kevin1024/vcrpy) - [Documentation](https://vcrpy.readthedocs.io/)
-
-A utility for record and repeat an http request.
+Provides authentication classes to be used with HTTPX's [authentication parameter](advanced/authentication.md#customizing-authentication).
 
 ### httpx-caching
 
@@ -70,22 +24,76 @@ A utility for record and repeat an http request.
 
 This package adds caching functionality to HTTPX
 
+### httpx-socks
+
+[GitHub](https://github.com/romis2012/httpx-socks)
+
+Proxy (HTTP, SOCKS) transports for httpx.
+
 ### httpx-sse
 
 [GitHub](https://github.com/florimondmanca/httpx-sse)
 
 Allows consuming Server-Sent Events (SSE) with HTTPX.
 
-### robox
+### httpx-retries
 
-[Github](https://github.com/danclaudiupop/robox)
+[GitHub](https://github.com/will-ockmore/httpx-retries) - [Documentation](https://will-ockmore.github.io/httpx-retries/)
 
-A library for scraping the web built on top of HTTPX.
+A retry layer for HTTPX.
+
+### httpx-ws
+
+[GitHub](https://github.com/frankie567/httpx-ws) - [Documentation](https://frankie567.github.io/httpx-ws/)
+
+WebSocket support for HTTPX.
+
+### pytest-HTTPX
+
+[GitHub](https://github.com/Colin-b/pytest_httpx) - [Documentation](https://colin-b.github.io/pytest_httpx/)
+
+Provides a [pytest](https://docs.pytest.org/en/latest/) fixture to mock HTTPX within test cases.
+
+### RESPX
+
+[GitHub](https://github.com/lundberg/respx) - [Documentation](https://lundberg.github.io/respx/)
+
+A utility for mocking out HTTPX.
+
+### rpc.py
+
+[Github](https://github.com/abersheeran/rpc.py) - [Documentation](https://github.com/abersheeran/rpc.py#rpcpy)
+
+A fast and powerful RPC framework based on ASGI/WSGI. Use HTTPX as the client of the RPC service.
+
+## Libraries with HTTPX support
+
+### Authlib
+
+[GitHub](https://github.com/lepture/authlib) - [Documentation](https://docs.authlib.org/en/latest/)
+
+A python library for building OAuth and OpenID Connect clients and servers. Includes an [OAuth HTTPX client](https://docs.authlib.org/en/latest/client/httpx.html).
+
+### Gidgethub
+
+[GitHub](https://github.com/brettcannon/gidgethub) - [Documentation](https://gidgethub.readthedocs.io/en/latest/index.html)
+
+An asynchronous GitHub API library. Includes [HTTPX support](https://gidgethub.readthedocs.io/en/latest/httpx.html).
+
+### httpdbg
+
+[GitHub](https://github.com/cle-b/httpdbg) - [Documentation](https://httpdbg.readthedocs.io/)
+
+A tool for python developers to easily debug the HTTP(S) client requests in a python program.
+
+### VCR.py
+
+[GitHub](https://github.com/kevin1024/vcrpy) - [Documentation](https://vcrpy.readthedocs.io/)
+
+Record and repeat requests.
 
 ## Gists
 
-<!-- NOTE: this list is in alphabetical order. -->
-
 ### urllib3-transport
 
 [GitHub](https://gist.github.com/florimondmanca/d56764d78d748eb9f73165da388e546e)
diff --git a/httpx/__version__.py b/httpx/__version__.py
index 0a684ac3..801bfacf 100644
--- a/httpx/__version__.py
+++ b/httpx/__version__.py
@@ -1,3 +1,3 @@
 __title__ = "httpx"
 __description__ = "A next generation HTTP client, for Python 3."
-__version__ = "0.28.0"
+__version__ = "0.28.1"
diff --git a/httpx/_client.py b/httpx/_client.py
index 2249231f..13cd9336 100644
--- a/httpx/_client.py
+++ b/httpx/_client.py
@@ -1723,7 +1723,7 @@ class AsyncClient(BaseClient):
 
         if not isinstance(request.stream, AsyncByteStream):
             raise RuntimeError(
-                "Attempted to send an sync request with an AsyncClient instance."
+                "Attempted to send a sync request with an AsyncClient instance."
             )
 
         with request_context(request=request):
diff --git a/httpx/_models.py b/httpx/_models.py
index 67d74bf8..2cc86321 100644
--- a/httpx/_models.py
+++ b/httpx/_models.py
@@ -964,7 +964,7 @@ class Response:
         Automatically called if the response body is read to completion.
         """
         if not isinstance(self.stream, SyncByteStream):
-            raise RuntimeError("Attempted to call an sync close on an async stream.")
+            raise RuntimeError("Attempted to call a sync close on an async stream.")
 
         if not self.is_closed:
             self.is_closed = True
@@ -1045,7 +1045,7 @@ class Response:
         if self.is_closed:
             raise StreamClosed()
         if not isinstance(self.stream, AsyncByteStream):
-            raise RuntimeError("Attempted to call an async iterator on an sync stream.")
+            raise RuntimeError("Attempted to call an async iterator on a sync stream.")
 
         self.is_stream_consumed = True
         self._num_bytes_downloaded = 0
@@ -1068,7 +1068,7 @@ class Response:
         Automatically called if the response body is read to completion.
         """
         if not isinstance(self.stream, AsyncByteStream):
-            raise RuntimeError("Attempted to call an async close on an sync stream.")
+            raise RuntimeError("Attempted to call an async close on a sync stream.")
 
         if not self.is_closed:
             self.is_closed = True
diff --git a/httpx/_transports/default.py b/httpx/_transports/default.py
index d5aa05ff..fc8c7097 100644
--- a/httpx/_transports/default.py
+++ b/httpx/_transports/default.py
@@ -355,7 +355,7 @@ class AsyncHTTPTransport(AsyncBaseTransport):
         else:  # pragma: no cover
             raise ValueError(
                 "Proxy protocol must be either 'http', 'https', 'socks5', or 'socks5h',"
-                " but got {proxy.url.scheme!r}."
+                f" but got {proxy.url.scheme!r}."
             )
 
     async def __aenter__(self: A) -> A:  # Use generics for subclass support.
diff --git a/pyproject.toml b/pyproject.toml
index 9e671911..675d2ad4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,6 +25,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "Topic :: Internet :: WWW/HTTP",
 ]
 dependencies = [
diff --git a/requirements.txt b/requirements.txt
index 0d8ba2ef..caa094f3 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -19,7 +19,7 @@ twine==6.0.1
 
 # Tests & Linting
 coverage[toml]==7.6.1
-cryptography==44.0.0
+cryptography==44.0.1
 mypy==1.13.0
 pytest==8.3.4
 ruff==0.8.1