diff --git a/tools/precommit/Dockerfile b/tools/precommit/Dockerfile
new file mode 100644
index 0000000000..1747d3a877
--- /dev/null
+++ b/tools/precommit/Dockerfile
@@ -0,0 +1,40 @@
+FROM ubuntu:20.04
+
+# author: Ole Schuett
+
+# Install Ubuntu packages.
+RUN export DEBIAN_FRONTEND=noninteractive DEBCONF_NONINTERACTIVE_SEEN=true && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    clang-format \
+    git \
+    less \
+    python3 \
+    python3-pip \
+    python3-wheel \
+    python3-setuptools \
+    rubygems \
+    shellcheck \
+    vim \
+  && rm -rf /var/lib/apt/lists/*
+
+# Install Markdownlint.
+RUN gem install mdl
+
+# Install Black Python Formatter.
+RUN pip3 install black
+
+# Clone cp2k repository (needed for CI mode).
+RUN git clone --quiet --recursive --single-branch -b master https://github.com/cp2k/cp2k.git /workspace/cp2k
+
+# Install Flask app.
+RUN pip3 install flask gunicorn
+WORKDIR /opt/cp2k-precommit
+COPY precommit_server.py .
+
+ARG REVISION
+ENV REVISION=${REVISION}
+
+COPY entrypoint.sh .
+CMD ["./entrypoint.sh"]
+
+#EOF
diff --git a/tools/precommit/README.md b/tools/precommit/README.md
new file mode 100644
index 0000000000..46514b8fc0
--- /dev/null
+++ b/tools/precommit/README.md
@@ -0,0 +1,41 @@
+# CP2K Precommit
+
+The precommit system consists of the following tools that analyze and format the source code:
+
+ - [doxify](../doxify/) to add Doxygen templates.
+ - [prettify](../prettify/) to format Fortran files.
+ - [analyze_src](../conventions/analyze_src.py) to check copyright banners and a few other things.
+ - [ast.parse](https://docs.python.org/3/library/ast.html) to check Python syntax.
+ - [clang-format](https://clang.llvm.org/docs/ClangFormat.html) to format C and Cuda files.
+ - [black](https://github.com/psf/black) to format Python scripts.
+ - [shellcheck](https://github.com/koalaman/shellcheck) to analyze Shell scripts.
+ - [markdownlint](https://github.com/markdownlint/markdownlint) to analyze Markdown files.
+
+In contrast to the [CP2K-CI](https://github.com/cp2k/cp2k-ci) these tools process each file individually, which makes them much more lightweight.
+
+## Install Git Hook
+
+The [precommit.py](./precommit.py) script can be readily installed as git hook:
+```
+ln -fs ../../tools/precommit/precommit.py .git/hooks/pre-commit
+```
+
+## Server
+
+Many of the tools listed above require more than just Python. To avoid their tedious installation a remote server is used by default.
+It is hosted at https://precommit.cp2k.org via [Cloud Run](https://cloud.google.com/run).
+
+The same server can also be started locally when Docker is available:
+```
+./start_local_server.sh
+```
+The server can also be installed without Docker by following the steps in the [Dockerfile](./Dockerfile).
+
+Once the server is up and running it can be used like this:
+```
+$ export CP2K_PRECOMMIT_SERVER="http://127.0.0.1:8080"
+$ ./precommit.py
+Running precommit checks using 8 workers and server: http://127.0.0.1:8080
+Searching for files...
+```
+
diff --git a/tools/precommit/cloudbuild.yaml b/tools/precommit/cloudbuild.yaml
new file mode 100644
index 0000000000..02a18f314a
--- /dev/null
+++ b/tools/precommit/cloudbuild.yaml
@@ -0,0 +1,28 @@
+# author: Ole Schuett
+
+steps:
+- name: 'gcr.io/cloud-builders/docker'
+  args: ["build", "--build-arg ", "REVISION=$SHORT_SHA", "-t", "img_cp2kprecommit", "."]
+
+- name: 'gcr.io/cloud-builders/docker'
+  args: ["tag", "img_cp2kprecommit", "gcr.io/$PROJECT_ID/img_cp2kprecommit:$SHORT_SHA"]
+
+- name: 'gcr.io/cloud-builders/docker'
+  args: ["push", "gcr.io/$PROJECT_ID/img_cp2kprecommit:$SHORT_SHA"]
+
+- name: 'gcr.io/cloud-builders/docker'
+  args: ["tag", "img_cp2kprecommit", "gcr.io/$PROJECT_ID/img_cp2kprecommit:latest"]
+
+- name: 'gcr.io/cloud-builders/docker'
+  args: ["push", "gcr.io/$PROJECT_ID/img_cp2kprecommit:latest"]
+
+- name: "gcr.io/cloud-builders/gcloud"
+  args:
+   - "run"
+   - "deploy"
+   - "cp2k-precommit"
+   - "--platform=managed"
+   - "--region=us-central1"
+   - "--image=gcr.io/$PROJECT_ID/img_cp2kprecommit:$SHORT_SHA"
+
+#EOF
diff --git a/tools/precommit/deploy.sh b/tools/precommit/deploy.sh
new file mode 100755
index 0000000000..e4dc10c6a5
--- /dev/null
+++ b/tools/precommit/deploy.sh
@@ -0,0 +1,18 @@
+#!/bin/bash -e
+
+# author: Ole Schuett
+
+set -x
+
+SHORT_SHA=$(git rev-parse --short HEAD)
+docker build --build-arg "REVISION=${SHORT_SHA}" -t cp2k-precommit .
+
+docker tag cp2k-precommit gcr.io/cp2k-org-project/img_cp2kprecommit:${SHORT_SHA}
+docker tag cp2k-precommit gcr.io/cp2k-org-project/img_cp2kprecommit:latest
+docker push gcr.io/cp2k-org-project/img_cp2kprecommit:${SHORT_SHA}
+docker push gcr.io/cp2k-org-project/img_cp2kprecommit:latest
+
+gcloud run deploy cp2k-precommit --platform=managed --region=us-central1 \
+    --image=gcr.io/cp2k-org-project/img_cp2kprecommit:${SHORT_SHA}
+
+#EOF
diff --git a/tools/precommit/entrypoint.sh b/tools/precommit/entrypoint.sh
new file mode 100755
index 0000000000..e40a1c65aa
--- /dev/null
+++ b/tools/precommit/entrypoint.sh
@@ -0,0 +1,28 @@
+#!/bin/bash -e
+
+# author: Ole Schuett
+
+trap "exit" INT
+
+if [ -z "${GIT_REF}" ]; then
+    # Server mode.
+    gunicorn --bind=:8080 --workers=1 --threads=8 --timeout=0 precommit_server:app &
+    wait  # Can be interrupted with ctrl-C.
+else
+    # CI mode.
+    echo -e "\n========== Starting Precommit Server =========="
+    gunicorn --bind=:8080 --workers=1 --threads=8 --timeout=0 precommit_server:app &> server.logs &
+    sleep 3
+    cat server.logs
+    echo -e "\n========== Fetching Git Commit =========="
+    cd /workspace/cp2k
+    git fetch --quiet origin "${GIT_BRANCH}"
+    git reset --quiet --hard "${GIT_REF}"
+    git submodule update --init --recursive
+    git --no-pager log -1 --pretty='%nCommitSHA: %H%nCommitTime: %ci%nCommitAuthor: %an%nCommitSubject: %s%n'
+    echo -e "\n========== Running Precommit Checks =========="
+    export CP2K_PRECOMMIT_SERVER="http://127.0.0.1:8080"
+    ./tools/precommit/precommit.py --no-cache --progressbar-wait=10  || true
+fi
+
+#EOF
diff --git a/tools/precommit/precommit.py b/tools/precommit/precommit.py
new file mode 100755
index 0000000000..ac1a70b3e4
--- /dev/null
+++ b/tools/precommit/precommit.py
@@ -0,0 +1,275 @@
+#!/usr/bin/python3
+
+# author: Ole Schuett
+
+import ast
+import argparse
+import json
+from time import time, sleep
+import re
+import os
+from os import path
+import sys
+import concurrent.futures
+from subprocess import PIPE, STDOUT
+import subprocess
+import traceback
+from urllib.request import urlopen, Request
+from urllib.error import HTTPError
+import uuid
+from difflib import unified_diff
+
+SCRATCH_DIR = "./obj/precommit"
+CACHE_FILE = path.join(SCRATCH_DIR, "cache.json")
+SERVER = os.environ.get("CP2K_PRECOMMIT_SERVER", "https://precommit.cp2k.org")
+
+
+# ======================================================================================
+def main():
+    # Parse command line arguments.
+    parser = argparse.ArgumentParser(
+        description="Check source code for formatting and linter problems."
+    )
+    parser.add_argument(
+        "-a",
+        "--no-cache",
+        action="store_true",
+        help="ignore the cache and check all files",
+    )
+    parser.add_argument(
+        "-m",
+        "--allow-modifications",
+        action="store_true",
+        help="allow the tools to modify files",
+    )
+    parser.add_argument(
+        "-j",
+        "--num_workers",
+        type=int,
+        default=min(32, os.cpu_count() + 4),  # copied from ThreadPoolExecutor
+        help="number of parallel workers",
+    )
+    parser.add_argument(
+        "--progressbar-wait",
+        type=int,
+        default=1,
+        help="number seconds in between progressbar updates",
+    )
+    args = parser.parse_args()
+
+    # Say hello to the server.
+    print(
+        f"Running precommit checks using {args.num_workers} workers and server: {SERVER}"
+    )
+    server_hello = urlopen(Request(SERVER + "/"), timeout=10).read().decode("utf8")
+    assert server_hello.startswith("cp2k precommit server")
+
+    # Change into base dir and create scratch dir.
+    base_dir = path.realpath(path.join(path.dirname(__file__), "../../"))
+    os.chdir(base_dir)
+    os.makedirs(SCRATCH_DIR, exist_ok=True)
+
+    # Collect eligible files.
+    sys.stdout.write("Searching for files...\r")
+    sys.stdout.flush()
+    filename_pattern = re.compile(r".*\.(F|fypp|c|cu|h|py)$")
+    file_list = []
+    for root, dirs, files in os.walk("."):
+        if root.startswith("./tools/toolchain/build"):
+            continue
+        if root.startswith("./tools/toolchain/install"):
+            continue
+        if root.startswith("./tools/prettify/fprettify"):
+            continue
+        if root.startswith("./tools/build_utils/fypp"):
+            continue
+        if root.startswith("./tools/autotune_grid"):
+            continue
+        if root.startswith("./exts"):
+            continue
+        if root.startswith("./obj"):
+            continue
+        if root.startswith("./lib"):
+            continue
+        if root.startswith("./exe"):
+            continue
+        if root.startswith("./regtesting"):
+            continue
+        if root.startswith("./.git"):
+            continue
+        file_list += [path.join(root, fn) for fn in files if filename_pattern.match(fn)]
+
+    # Load cache.
+    should_load_cache = path.exists(CACHE_FILE) and not args.no_cache
+    cache = json.load(open(CACHE_FILE)) if should_load_cache else {}
+
+    # Launch async processing of files.
+    futures = {}
+    executor = concurrent.futures.ThreadPoolExecutor(max_workers=args.num_workers)
+    for fn in file_list:
+        if path.getmtime(fn) != cache.get(fn, -1):
+            futures[fn] = executor.submit(process_file, fn, args.allow_modifications)
+    num_skipped = len(file_list) - len(futures)
+
+    # Continuously update progressbar, save cache file, and print errors.
+    failed_files = set()
+    while True:
+        num_done = num_skipped
+        for fn, f in futures.items():
+            if f.done():
+                num_done += 1
+                if not f.exception():
+                    cache[fn] = path.getmtime(fn)
+                elif fn not in failed_files:
+                    failed_files.add(fn)
+                    print_box(fn, str(f.exception()))
+        json.dump(cache, open(CACHE_FILE, "w"))
+        progressbar = "=" * int(60 * num_done / len(file_list))
+        sys.stdout.write(
+            f"[{progressbar:60s}] {num_done} / {len(file_list)} files processed\r"
+        )
+        sys.stdout.flush()
+        if num_done == len(file_list) or len(failed_files) >= 10:
+            executor.shutdown(wait=False)
+            break
+        sleep(args.progressbar_wait)
+
+    # Print final message.
+    print(
+        f"Summary: Found {len(file_list)}, "
+        f"skipped {num_skipped}, "
+        f"checked {num_done - num_skipped}, "
+        f"and failed {len(failed_files)} files." + (" " * 50)
+    )
+    print("Status: " + ("FAILED" if failed_files else "OK"))
+    sys.exit(len(failed_files))
+
+
+# ======================================================================================
+def print_box(fn, message):
+    print("+" + "-" * 160 + "+")
+    print(f"| {fn:^158s} |")
+    print("+" + "-" * 160 + "+")
+    for line in message.strip().split("\n"):
+        print(f"| {line:<158s} |")
+    print("+" + "-" * 160 + "+\n\n")
+
+
+# ======================================================================================
+def process_file(fn, allow_modifications):
+    orig_content = open(fn, "rb").read()
+
+    if re.match(r".*\.(F|fypp)$", fn):
+        run_local_tool("./tools/doxify/doxify.sh", fn)
+        run_prettify(fn)
+        run_analyze_src(fn)
+
+    elif re.match(r".*\.(c|cu|cpp|h|hpp)$", fn):
+        run_remote_tool("clangformat", fn)
+        run_analyze_src(fn)
+
+    elif re.match(r".*\.py$", fn):
+        ast.parse(orig_content, filename=fn)
+        run_remote_tool("black", fn)
+        run_analyze_src(fn)
+
+    elif re.match(r".*\.sh$", fn):
+        run_remote_tool("shellcheck", fn)
+
+    elif re.match(r".*\.md$", fn):
+        run_remote_tool("markdownlint", fn)
+
+    else:
+        raise Exception("Unknown file extension: " + fn)
+
+    new_content = open(fn, "rb").read()
+    if new_content == orig_content:
+        return
+
+    # Deal with a modified file.
+    if allow_modifications:
+        bak_fn = path.join(SCRATCH_DIR, f"{path.basename(fn)}_{int(time())}.bak")
+        open(bak_fn, "wb").write(orig_content)  # make a backup copy
+    else:
+        open(fn, "wb").write(orig_content)  # restore origin content
+        try:
+            orig_lines = orig_content.decode("utf8").split("\n")
+            new_lines = new_content.decode("utf8").split("\n")
+            diff = unified_diff(orig_lines, new_lines, "before", "after", lineterm="")
+        except:
+            diff = []  #
+        raise Exception(f"File modified:\n" + "\n".join(diff))
+
+
+# ======================================================================================
+def run_prettify(fn):
+    if fn in ("./src/base/base_uses.f90", "./src/common/util.F"):
+        return  # Skipping because of prettify bugs.
+
+    # The prettify tool processes only about 1k lines of code per second.
+    # Hence, setting a generous timeout as our largest file has 100k lines.
+    run_local_tool(
+        "./tools/prettify/prettify.py", "--no-report-errors", fn, timeout=300
+    )
+
+
+# ======================================================================================
+def run_analyze_src(fn):
+    run_local_tool(
+        "./tools/conventions/analyze_src.py",
+        "--fail",
+        "--suppressions",
+        "./tools/conventions/conventions.supp",
+        fn,
+    )
+
+
+# ======================================================================================
+def run_local_tool(*cmd, timeout=10):
+    p = subprocess.run(cmd, timeout=timeout, stdout=PIPE, stderr=STDOUT)
+    if p.returncode != 0:
+        raise Exception(p.stdout.decode("utf8"))
+
+
+# ======================================================================================
+def run_remote_tool(tool, fn):
+    url = f"{SERVER}/{tool}"
+    r = http_post(url, fn)
+    if r.status == 304:
+        pass  # file not modified
+    elif r.status == 200:
+        open(fn, "wb").write(r.read())
+    else:
+        raise Exception(r.read().decode("utf8"))  # something went wrong
+
+
+# ======================================================================================
+def http_post(url, fn):
+    # This would be so much easier with the Requests library where it'd be a one-liner:
+    #    return requests.post(url, files={path.basename(fn): open(fn, "rb").read()})
+
+    boundary = uuid.uuid1().hex
+    name = path.basename(fn)
+    data = b"".join(
+        [
+            f"--{boundary}\r\nContent-Disposition: ".encode("utf8"),
+            f'form-data; name="{name}"; filename="{name}"\r\n\r\n'.encode("utf8"),
+            open(fn, "rb").read(),
+            f"\r\n--{boundary}--\r\n".encode("utf8"),
+        ]
+    )
+    headers = {
+        "Content-Length": len(data),
+        "Content-Type": f"multipart/form-data; boundary={boundary}",
+    }
+    try:
+        return urlopen(Request(url, data=data, headers=headers), timeout=60)
+    except HTTPError as err:
+        return err  # HTTPError has .status and .read() just like a normal HTTPResponse.
+
+
+# ======================================================================================
+if __name__ == "__main__":
+    main()
+
+# EOF
diff --git a/tools/precommit/precommit_server.py b/tools/precommit/precommit_server.py
new file mode 100755
index 0000000000..0bec5e629c
--- /dev/null
+++ b/tools/precommit/precommit_server.py
@@ -0,0 +1,83 @@
+#!/usr/bin/python3
+
+# author: Ole Schuett
+
+import os
+import logging
+from os import path
+from time import time
+import tempfile
+import subprocess
+from subprocess import PIPE, STDOUT
+from flask import Flask, request, abort
+
+app = Flask(__name__)
+app.config["MAX_CONTENT_LENGTH"] = 1024 * 1024  # 1MB
+app.logger.setLevel(logging.INFO)
+app.logger.info("CP2K Precommit Server is up and running :-)")
+
+# ======================================================================================
+@app.route("/")
+def hello():
+    return "cp2k precommit server revision: " + os.environ["REVISION"]
+
+
+# ======================================================================================
+@app.route("/black", methods=["POST"])
+def black():
+    return run_tool(["black"])
+
+
+# ======================================================================================
+@app.route("/shellcheck", methods=["POST"])
+def shellcheck():
+    return run_tool(["shellcheck"])
+
+
+# ======================================================================================
+@app.route("/markdownlint", methods=["POST"])
+def markdownlint():
+    return run_tool(["mdl"])
+
+
+# ======================================================================================
+@app.route("/clangformat", methods=["POST"])
+def clangformat():
+    return run_tool(["clang-format", "--style=llvm", "-i"])
+
+
+# ======================================================================================
+def run_tool(cmd, timeout=30):
+    assert len(request.files) == 1
+    orig_fn = list(request.files.keys())[0]
+    data_before = request.files[orig_fn].read()
+    data_kb = len(data_before) / 1024.0
+    fn = path.basename(orig_fn)
+    workdir = tempfile.TemporaryDirectory()
+    abs_fn = path.join(workdir.name, fn)
+    open(abs_fn, "wb").write(data_before)
+
+    t1 = time()
+    try:
+        p = subprocess.run(
+            cmd + [fn], cwd=workdir.name, timeout=timeout, stdout=PIPE, stderr=STDOUT
+        )
+    except subprocess.TimeoutExpired:
+        app.logger.info(f"Timeout of {cmd[0]} on {data_kb:.1f}KB after {timeout}s.")
+        return f"Timeout while running {cmd[0]} - please try again.", 504
+    t2 = time()
+    app.logger.info(f"Ran {cmd[0]} on {data_kb:.1f}KB in {t2-t1:.1f}s.")
+
+    if p.returncode != 0:
+        return p.stdout, 422  # Unprocessable Entity
+    data_after = open(abs_fn, "rb").read()
+    if data_after == data_before:
+        return "Not Modified", 304
+    return data_after, 200
+
+
+# ======================================================================================
+if __name__ == "__main__":
+    app.run()
+
+# EOF
diff --git a/tools/precommit/start_local_server.sh b/tools/precommit/start_local_server.sh
new file mode 100755
index 0000000000..19869094bf
--- /dev/null
+++ b/tools/precommit/start_local_server.sh
@@ -0,0 +1,11 @@
+#!/bin/bash -e
+
+# author: Ole Schuett
+
+set -x
+
+SHORT_SHA=$(git rev-parse --short HEAD)
+docker build --build-arg "REVISION=${SHORT_SHA}" -t cp2k-precommit .
+docker run --rm -p127.0.0.1:8080:8080 cp2k-precommit
+
+#EOF