diff --git a/README.md b/README.md
index 854b501..1d1c3d7 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,7 @@
 # infravelo-py
 
+[![CI](https://github.com/phansch/infravelo-py/actions/workflows/python.yml/badge.svg)](https://github.com/phansch/infravelo-py/actions/workflows/python.yml)
+
 Some tools based on the [infravelo.de](https://infravelo.de) API and website.
 
 * API fetcher
diff --git a/poetry.lock b/poetry.lock
index 2798e86..e8fe432 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -247,6 +247,19 @@ files = [
 dev = ["pre-commit", "tox"]
 testing = ["pytest", "pytest-benchmark"]
 
+[[package]]
+name = "py-dateutil"
+version = "2.2"
+description = "Extensions to the standard Python datetime module"
+optional = false
+python-versions = "*"
+files = [
+    {file = "py-dateutil-2.2.tar.gz", hash = "sha256:7efa2ca17159c590408cb624de9aa10d360f14097cb70dd7559e632f2cf4b048"},
+]
+
+[package.dependencies]
+six = "*"
+
 [[package]]
 name = "pytest"
 version = "8.1.1"
@@ -288,6 +301,17 @@ urllib3 = ">=1.21.1,<3"
 socks = ["PySocks (>=1.5.6,!=1.5.7)"]
 use-chardet-on-py3 = ["chardet (>=3.0.2,<6)"]
 
+[[package]]
+name = "six"
+version = "1.16.0"
+description = "Python 2 and 3 compatibility utilities"
+optional = false
+python-versions = ">=2.7, !=3.0.*, !=3.1.*, !=3.2.*"
+files = [
+    {file = "six-1.16.0-py2.py3-none-any.whl", hash = "sha256:8abb2f1d86890a2dfb989f9a77cfcfd3e47c2a354b01111771326f8aa26e0254"},
+    {file = "six-1.16.0.tar.gz", hash = "sha256:1e61c37477a1626458e36f7b1d82aa5c9b094fa4802892072e49de9c60c4c926"},
+]
+
 [[package]]
 name = "soupsieve"
 version = "2.5"
@@ -330,4 +354,4 @@ zstd = ["zstandard (>=0.18.0)"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.12"
-content-hash = "f96b6643f3e96f7f811d8a4db898494897a83553fa41b63c9f2052de61a284af"
+content-hash = "6566854348befa86354ac8e9b03659ede8ee9ec33fbadef1a4280e661d42afbb"
diff --git a/pyproject.toml b/pyproject.toml
index 8519874..22af92a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,6 +14,7 @@ packages = [
 python = "^3.12"
 requests = "^2.31.0"
 beautifulsoup4 = "^4.12.3"
+py-dateutil = "^2.2"
 
 [tool.poetry.group.dev.dependencies]
 mypy = "*"
diff --git a/sync/core.py b/sync/core.py
index 36dcc6d..0eab2d5 100644
--- a/sync/core.py
+++ b/sync/core.py
@@ -1,10 +1,9 @@
-from api_fetcher import core as api_fetcher
-from scraper import core as scraper
 from enum import Enum
 from pathlib import Path
 import os
-from urllib.parse import urlparse, unquote
-import requests
+from sync import runner
+
+# Various util methods for filesystem and request things
 
 class ProjectState(Enum):
     DONE = "Abgeschlossen"
@@ -18,10 +17,6 @@ def without_done_projects(project):
 def project_slug_from_url(project_url):
     return project_url.split('/')[-2]
 
-def filename_from_url(url: str) -> str:
-    path = urlparse(url).path
-    return unquote(Path(path).name)
-
 def root_dir() -> Path:
     return Path(__file__).parent.parent
 
@@ -30,24 +25,10 @@ def dir_for_project(project) -> Path:
 
 def create_project_dirs(projects):
     for project in projects:
-        dir_for_project(project).mkdir(parents=True,exist_ok=True)
+        create_dir_if_not_exists(dir_for_project(project))
+
+def create_dir_if_not_exists(path: Path):
+    path.mkdir(parents=True,exist_ok=True)
 
 def run():
-    all_projects = api_fetcher.all_projects();
-    print(f"Downloaded {len(all_projects)} projects from the Infravelo API")
-
-    # Select projects that are not finished yet, to avoid needless scraping
-    projects_to_scrape = list(filter(without_done_projects, all_projects))
-    print(f"About to scrape {len(projects_to_scrape)} projects.")
-
-    create_project_dirs(projects_to_scrape)
-
-    for project in projects_to_scrape:
-        print(f"Scraping {project["link"]}")
-        document_urls = scraper.get_document_urls_from_page(project['link'])
-        for url in document_urls:
-            path = dir_for_project(project) / filename_from_url(url)
-            print(f"Downloading {url} to {path}")
-            response = requests.get(url)
-            with open(path, 'wb') as f:
-                f.write(response.content)
+    runner.run()
diff --git a/sync/document_downloader.py b/sync/document_downloader.py
new file mode 100644
index 0000000..3203bed
--- /dev/null
+++ b/sync/document_downloader.py
@@ -0,0 +1,28 @@
+import requests
+from urllib.parse import urlparse, unquote
+from dateutil.parser import parse as parsedate
+from pathlib import Path
+from sync import core
+
+def filename_from_url(url: str) -> str:
+    path = urlparse(url).path
+    return unquote(Path(path).name)
+
+def last_modified_date(headers) -> str:
+    # https://stackoverflow.com/a/70641487/6830113
+    import collections
+    collections.Callable = collections.abc.Callable
+    last_modified = headers["last-modified"]
+    url_date = parsedate(last_modified)
+    return url_date.strftime("%Y-%m-%d")
+
+def download(project: any, url: str):
+    # TODO: Get the latest document on disk
+    response = requests.get(url)
+    filepath = core.dir_for_project(project) / last_modified_date(response.headers) / filename_from_url(url)
+    core.create_dir_if_not_exists(filepath.parent)
+    print(f"Downloaded {url} to {filepath}")
+    # TODO: Don't create day dir if no changes happened
+    # if changed_date > last_date, write new file
+    with open(filepath, 'wb') as f:
+        f.write(response.content)
diff --git a/sync/runner.py b/sync/runner.py
new file mode 100644
index 0000000..12ace4b
--- /dev/null
+++ b/sync/runner.py
@@ -0,0 +1,32 @@
+from sync import document_downloader
+from sync import core
+from api_fetcher import core as api_fetcher
+from scraper import core as scraper
+from datetime import date
+import json
+
+def project_to_json(project: dict):
+    filepath = core.dir_for_project(project) / date.today().strftime("%Y-%m-%d") / "project.json"
+    core.create_dir_if_not_exists(filepath.parent)
+    with open(filepath, "w") as outfile:
+        json.dump(project, outfile)
+
+def run():
+    today = date.today() # format: 2024-12-21
+    all_projects = api_fetcher.all_projects();
+    print(f"Downloaded {len(all_projects)} projects from the Infravelo API")
+
+    # Select projects that are not finished yet, to avoid needless scraping
+    projects_to_scrape = list(filter(core.without_done_projects, all_projects))
+    print(f"About to scrape {len(projects_to_scrape)} projects.")
+
+    core.create_project_dirs(projects_to_scrape)
+
+    for project in projects_to_scrape:
+        print(f"Scraping {project["link"]}")
+        project_to_json(project)
+        # TODO: Skip project if already checked today
+        # TODO: Download json
+        document_urls = scraper.get_document_urls_from_page(project['link'])
+        for url in document_urls:
+            document_downloader.download(project, url)
diff --git a/tests/test_document_downloader.py b/tests/test_document_downloader.py
new file mode 100644
index 0000000..75df477
--- /dev/null
+++ b/tests/test_document_downloader.py
@@ -0,0 +1,23 @@
+from sync import document_downloader as document_downloader
+
+def test_filename_from_url():
+    url = "https://www.example.com./projekt/oderberger-strasse-8/"
+    result = document_downloader.filename_from_url(url)
+    assert result == "oderberger-strasse-8"
+
+    url = "https://www.example.com./projekt/oderberger-strasse-8/filename.pdf"
+    result = document_downloader.filename_from_url(url)
+    assert result == "filename.pdf"
+
+    url = "https://www.example.com/projekt/oderberger-strasse-8/filename.pdf?1234"
+    result = document_downloader.filename_from_url(url)
+    assert result == "filename.pdf"
+
+    url = "https://www.example.com/projekt/oderberger-strasse-8/filename.pdf?1234#abc"
+    result = document_downloader.filename_from_url(url)
+    assert result == "filename.pdf"
+
+def test_last_modified_date():
+    headers = { "last-modified": "Tue, 30 Apr 2024 07:38:39 GMT" }
+    result = document_downloader.last_modified_date(headers)
+    assert result == '2024-04-30'
diff --git a/tests/test_sync.py b/tests/test_sync.py
index 680981d..218bfe5 100644
--- a/tests/test_sync.py
+++ b/tests/test_sync.py
@@ -1,33 +1,16 @@
-from sync import core as sync
+from sync import core
 from pathlib import Path
 
 def test_filter():
     p1 = [{ 'status': 'Abgeschlossen' }, { 'status': 'in Bau'}]
-    result = list(filter(sync.without_done_projects, p1))
+    result = list(filter(core.without_done_projects, p1))
     assert result == [{ 'status': 'in Bau'}]
 
 
 def test_project_slug_from_url():
     url = "https://www.example.com/projekt/oderberger-strasse-8/"
-    result = sync.project_slug_from_url(url)
+    result = core.project_slug_from_url(url)
     assert result == "oderberger-strasse-8"
 
-def test_filename_from_url():
-    url = "https://www.example.com./projekt/oderberger-strasse-8/"
-    result = sync.filename_from_url(url)
-    assert result == "oderberger-strasse-8"
-
-    url = "https://www.example.com./projekt/oderberger-strasse-8/filename.pdf"
-    result = sync.filename_from_url(url)
-    assert result == "filename.pdf"
-
-    url = "https://www.example.com/projekt/oderberger-strasse-8/filename.pdf?1234"
-    result = sync.filename_from_url(url)
-    assert result == "filename.pdf"
-
-    url = "https://www.example.com/projekt/oderberger-strasse-8/filename.pdf?1234#abc"
-    result = sync.filename_from_url(url)
-    assert result == "filename.pdf"
-
 def test_root_dir():
-    assert sync.root_dir().name == "infravelo-py"
+    assert core.root_dir().name == "infravelo-py"