diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..3ae5eb0
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,7 @@
+# Change Log
+All notable changes to this project will be documented in this file.
+This project adheres to [Semantic Versioning](http://semver.org/).
+
+## [UNRELEASED] - 0000-00-00
+### Added
+- Support callback_url in API requests (#10)
\ No newline at end of file
diff --git a/quickpay_api_client/api.py b/quickpay_api_client/api.py
index 72ef0f1..0295f02 100644
--- a/quickpay_api_client/api.py
+++ b/quickpay_api_client/api.py
@@ -50,6 +50,10 @@ class QPApi(object):
             "User-Agent": "quickpay-python-client, v%s" % quickpay_api_client.__version__
         }
 
+        callback_url = kwargs.pop("callback_url", None)
+        if callback_url:
+            headers["Quickpay-Callback-Url"] = callback_url
+
         if self.secret:
             headers["Authorization"
                     ] = "Basic {0}".format(_base64_encode(self.secret))

QuickPay-Callback-Url
It is not possible to change the header QuickPay-Callback-Url using this client.

This would be useful when it is not accepted in the body, e.g. 
[POST /subscriptions/{id}/recurring](https://learn.quickpay.net/tech-talk/api/services/#POST-subscriptions--id-recurring---format-)
diff --git a/quickpay_api_client/tests/api_tests.py b/quickpay_api_client/tests/api_tests.py
index 8133e8f..066235b 100644
--- a/quickpay_api_client/tests/api_tests.py
+++ b/quickpay_api_client/tests/api_tests.py
@@ -43,6 +43,15 @@ class TestApi(object):
         assert_equal(req_headers['Accept-Version'], 'v10')
         assert req_headers['User-Agent']
 
+    @responses.activate
+    def test_callback_url_headers(self):
+        self.setup_request()
+        callback_url = "https://foo.bar"
+        res = self.api.perform("get", "/test", callback_url=callback_url)
+
+        req_headers = responses.calls[0].request.headers
+        assert_equal(req_headers['Quickpay-Callback-Url'], callback_url)
+
     @responses.activate
     def test_perform_when_raw(self):
         self.setup_request()

pip install -e .
parse_log_pytest
requirements.txt
pytest
3.7
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
certifi @ file:///croot/certifi_1671487769961/work/certifi
charset-normalizer==3.4.1
cookies==2.2.1
exceptiongroup==1.2.2
idna==3.10
importlib-metadata==6.7.0
iniconfig==2.0.0
mock==1.0.1
nose==1.3.6
packaging==24.0
pluggy==1.2.0
pytest==7.4.4
-e git+https://github.com/QuickPay/quickpay-python-client.git@d74eb0caf3d12ff53617b156f5f6f35189cf13b3#egg=quickpay_api_client
requests==2.31.0
responses==0.8.1
six==1.17.0
tomli==2.0.1
typing_extensions==4.7.1
urllib3==2.0.7
zipp==3.15.0

name: quickpay-python-client
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2022.12.7=py37h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=22.3.1=py37h06a4308_0
  - python=3.7.16=h7a1cb2a_0
  - readline=8.2=h5eee18b_0
  - setuptools=65.6.3=py37h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.38.4=py37h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - charset-normalizer==3.4.1
      - cookies==2.2.1
      - exceptiongroup==1.2.2
      - idna==3.10
      - importlib-metadata==6.7.0
      - iniconfig==2.0.0
      - mock==1.0.1
      - nose==1.3.6
      - packaging==24.0
      - pluggy==1.2.0
      - pytest==7.4.4
      - requests==2.31.0
      - responses==0.8.1
      - six==1.17.0
      - tomli==2.0.1
      - typing-extensions==4.7.1
      - urllib3==2.0.7
      - zipp==3.15.0
prefix: /opt/conda/envs/quickpay-python-client

quickpay_api_client/tests/api_tests.py::TestApi::test_callback_url_headers
quickpay_api_client/tests/api_tests.py::TestApi::test_perform_success quickpay_api_client/tests/api_tests.py::TestApi::test_perform_failure quickpay_api_client/tests/api_tests.py::TestApi::test_headers quickpay_api_client/tests/api_tests.py::TestApi::test_perform_when_raw
quickpay_api_client/api.py CHANGELOG.md
quickpay_api_client/api.py CHANGELOG.md