diff --git a/README.md b/README.md
index 937bfba..4400a71 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ So a as an example an audio-file could be assigned to project `+album` and have
 $ uv tool install 'orvanitag[all]'
 ```
 
-Requires Python 3.11 or newer. The core only needs rich. Reading and writing embedded metadata uses optional extras: `audio` (pytaglib, needs the TagLib C library), `pdf` (pypdf), `office` (olefile, only for legacy `.doc`/`.xls`/`.ppt`) and `markdown` (python-frontmatter). Plugins whose extra is not installed are skipped.
+Requires Python 3.11 or newer. The core only needs rich. Reading and writing embedded metadata uses optional extras: `audio` (pytaglib, needs the TagLib C library), `pdf` (pypdf), `office` (olefile, only for legacy `.doc`/`.xls`/`.ppt`) and `markdown` (PyYAML). Plugins whose extra is not installed are skipped.
 
 ## Command Line Tool
 
@@ -114,7 +114,7 @@ $ otag write id3 song.mp3
 | `id3` | `.mp3` `.wav` `.flac` `.ogg` | The comment tag |
 | `pdf` | `.pdf` | The keywords field |
 | `office` | `.docx` `.xlsx` `.pptx` `.odt` `.ods` `.odp`, reading also `.doc` `.xls` `.ppt` | The description field |
-| `frontmatter` | `.md` `.txt` `.markdown` `.rst` | `projects`, `contexts`, `tags` and `note` keys of the YAML front matter |
+| `frontmatter` | `.md` `.markdown` `.txt` | `projects`, `contexts`, `tags` and `note` keys of the YAML front matter; other keys, comments and formatting are left untouched |
 | `comment` | Source code such as `.py` `.sh` `.toml` `.js` `.c` `.go` `.rs` `.php` `.html` | An `otag: +project @context #tag note` comment line within the first ten lines, written in the file's comment style below any shebang, encoding, `<!DOCTYPE>` or `<?php` line |
 
 ### Import and Export
diff --git a/orvanitag/plugins/frontmatter.py b/orvanitag/plugins/frontmatter.py
index ea8e13b..c346dd3 100644
--- a/orvanitag/plugins/frontmatter.py
+++ b/orvanitag/plugins/frontmatter.py
@@ -1,22 +1,103 @@
-import frontmatter
-from pathlib import Path
+"""
+Tags as `projects`, `contexts`, `tags` and `note` keys of a Markdown file's YAML front matter.
+Writing edits only those lines, so other keys, comments and formatting stay as they are.
+"""
+import json
+import os
+import re
+import shutil
+import yaml
 
 NAME = 'frontmatter'
-TYPES = ['.md', '.txt', '.markdown', '.rst']
+TYPES = ['.md', '.markdown', '.txt']
+
+DELIMITER = '---'
+PLAIN = re.compile(r'[A-Za-z][\w-]*')
+# Plain words YAML 1.1 would read as booleans or null
+SPECIAL = {'y', 'n', 'yes', 'no', 'on', 'off', 'true', 'false', 'null'}
+
+
+def block(lines: list):
+    """Returns the line range between the front matter delimiters, or None"""
+    if lines and lines[0].strip() == DELIMITER:
+        for num, line in enumerate(lines[1:], start=1):
+            if line.strip() in (DELIMITER, '...'):
+                return 1, num
+    return None
+
+
+def words(value) -> list:
+    """Tags from a YAML list or a comma or space separated string; spaces inside a tag become dashes"""
+    if isinstance(value, list):
+        items = value
+    else:
+        items = str(value).split(',') if ',' in str(value) else str(value).split()
+    return ['-'.join(str(item).split()) for item in items if str(item).strip()]
+
+
+def scalar(value: str) -> str:
+    if PLAIN.fullmatch(value) and value.lower() not in SPECIAL:
+        return value
+    return json.dumps(value, ensure_ascii=False) # a JSON string is a valid YAML double-quoted scalar
+
 
 def reader(o):
-    with open(o.file, 'r') as data:
-        y = frontmatter.load(data)
-        if y.metadata:
-            context = y.metadata.copy()
-            for meta in y.metadata.keys():
-                if not meta in o.schema:
-                    del context[meta]
-            return context
-        
+    with o.file.open(encoding='utf-8') as data:
+        lines = data.readlines()
+    span = block(lines)
+    if not span:
+        return None
+    # BaseLoader keeps every value a string, so `2023` or `yes` stay as written
+    metadata = yaml.load(''.join(lines[span[0]:span[1]]), Loader=yaml.BaseLoader)
+    if not isinstance(metadata, dict):
+        return None
+
+    context = {}
+    for key, prefix in o.schema.items():
+        if metadata.get(key):
+            context[key] = words(metadata[key]) if prefix else ' '.join(str(metadata[key]).split())
+    if any(context.values()):
+        return context
+
+
 def writer(o):
-    y = frontmatter.load(o.file)
-    for key in o.context:
-        y[key] = o.context[key]
-    with open(o.file, 'w') as data:
-        data.write(frontmatter.dumps(y))
\ No newline at end of file
+    with o.file.open(encoding='utf-8', newline='') as data: # keeps \r\n line endings
+        text = data.read()
+    lines = text.splitlines(keepends=True)
+    newline = '\r\n' if '\r\n' in text else '\n'
+
+    entries = {}
+    for key, prefix in o.schema.items():
+        value = o.context.get(key)
+        if value: # empty categories leave existing keys alone
+            rendered = f'[{", ".join(scalar(tag) for tag in value)}]' if prefix else scalar(value)
+            entries[key] = f'{key}: {rendered}{newline}'
+    if not entries:
+        return
+
+    span = block(lines)
+    if not span:
+        lines[0:0] = [DELIMITER + newline, *entries.values(), DELIMITER + newline]
+    else:
+        start, end = span
+        for key, entry in entries.items():
+            found = next((num for num in range(start, end) if re.match(rf'{re.escape(key)}\s*:', lines[num])), None)
+            if found is None:
+                lines.insert(end, entry)
+                end += 1
+            else:
+                # The value continues on indented lines or top-level list items
+                stop = found + 1
+                while stop < end and lines[stop].startswith((' ', '\t', '-')):
+                    stop += 1
+                lines[found:stop] = [entry]
+                end -= stop - found - 1
+
+    tmp = o.file.with_name(f'.{o.file.name}.tmp')
+    try:
+        with open(tmp, 'w', encoding='utf-8', newline='') as data:
+            data.write(''.join(lines))
+        shutil.copymode(o.file, tmp)
+        os.replace(tmp, o.file)
+    finally:
+        tmp.unlink(missing_ok=True)
diff --git a/pyproject.toml b/pyproject.toml
index 6829042..f2caf48 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -25,7 +25,7 @@ dependencies = [
 audio = ["pytaglib>=2.0.0"]
 pdf = ["pypdf>=4.0"]
 office = ["olefile>=0.46"]
-markdown = ["python-frontmatter>=1.0"]
+markdown = ["PyYAML>=6.0"]
 all = ["orvanitag[audio,pdf,office,markdown]"]
 
 [project.urls]
diff --git a/tests/test_frontmatter.py b/tests/test_frontmatter.py
new file mode 100644
index 0000000..c197972
--- /dev/null
+++ b/tests/test_frontmatter.py
@@ -0,0 +1,72 @@
+import pytest
+
+import orvanitag.orvani as orvani
+from orvanitag.orvani import OrvaniTag
+
+
+@pytest.fixture
+def cwd(tmp_path, monkeypatch):
+    monkeypatch.chdir(tmp_path)
+    return tmp_path
+
+
+def scanned(cwd):
+    OrvaniTag().scan('.', False)
+    return (cwd / orvani.CONTEXT_FILE).read_text()
+
+
+def test_reads_lists_strings_and_plain_scalars(cwd):
+    (cwd / 'a.md').write_text('---\ntags: lofi\nprojects: album\nnote: first take\n---\n')
+    (cwd / 'b.md').write_text('---\ntags: "blog, lo fi"\n---\n')
+    (cwd / 'c.md').write_text('---\ntags: [2023, yes]\ncontexts:\n  - desk\n---\n')
+    assert scanned(cwd) == (
+        'a.md --- +album #lofi first take\n'
+        'b.md --- #blog #lo-fi\n'
+        'c.md --- @desk #2023 #yes\n'
+    )
+
+
+def test_write_changes_only_its_own_keys(cwd):
+    post = '---\ntitle: Post\n# my comment\ndate: 2024-01-05\ntags:\n  - blog\n  - lo-fi\nlayout: post\n---\nBody text.\n'
+    (cwd / 'post.md').write_text(post)
+    o = OrvaniTag()
+    o.add('post.md', '#blog', '#lo-fi', '#new')
+    assert o.write_metadata('post.md', 'frontmatter')[0] == 0
+    assert (cwd / 'post.md').read_text() == (
+        '---\ntitle: Post\n# my comment\ndate: 2024-01-05\ntags: [blog, lo-fi, new]\nlayout: post\n---\nBody text.\n'
+    )
+
+
+def test_write_adds_missing_keys_and_quotes_when_needed(cwd):
+    (cwd / 'a.md').write_text('---\ntitle: A\n---\ntext\n')
+    o = OrvaniTag()
+    o.add('a.md', '+c++', '#yes', 'a: note')
+    o.write_metadata('a.md', 'frontmatter')
+    assert (cwd / 'a.md').read_text() == '---\ntitle: A\nprojects: ["c++"]\ntags: ["yes"]\nnote: "a: note"\n---\ntext\n'
+
+    (cwd / orvani.CONTEXT_FILE).unlink()
+    assert scanned(cwd) == 'a.md --- +c++ #yes a: note\n'
+
+
+def test_write_creates_front_matter_and_keeps_crlf(cwd):
+    (cwd / 'a.md').write_bytes(b'# Heading\r\n')
+    o = OrvaniTag()
+    o.add('a.md', '#lofi')
+    o.write_metadata('a.md', 'frontmatter')
+    assert (cwd / 'a.md').read_bytes() == b'---\r\ntags: [lofi]\r\n---\r\n# Heading\r\n'
+
+
+def test_empty_categories_leave_existing_keys_alone(cwd):
+    (cwd / 'a.md').write_text('---\nprojects: [old]\n---\n')
+    o = OrvaniTag()
+    o.add('a.md', '#lofi')
+    o.write_metadata('a.md', 'frontmatter')
+    assert (cwd / 'a.md').read_text() == '---\nprojects: [old]\ntags: [lofi]\n---\n'
+
+
+def test_rst_is_not_handled(cwd):
+    (cwd / 'doc.rst').write_text('Title\n=====\n')
+    o = OrvaniTag()
+    o.add('doc.rst', '#x')
+    assert o.write_metadata('doc.rst', 'frontmatter')[0] == 4
+    assert (cwd / 'doc.rst').read_text() == 'Title\n=====\n'
diff --git a/uv.lock b/uv.lock
index c48f9f2..bfc69fe 100644
--- a/uv.lock
+++ b/uv.lock
@@ -63,13 +63,13 @@ all = [
     { name = "olefile" },
     { name = "pypdf" },
     { name = "pytaglib" },
-    { name = "python-frontmatter" },
+    { name = "pyyaml" },
 ]
 audio = [
     { name = "pytaglib" },
 ]
 markdown = [
-    { name = "python-frontmatter" },
+    { name = "pyyaml" },
 ]
 office = [
     { name = "olefile" },
@@ -90,7 +90,7 @@ requires-dist = [
     { name = "orvanitag", extras = ["audio", "pdf", "office", "markdown"], marker = "extra == 'all'" },
     { name = "pypdf", marker = "extra == 'pdf'", specifier = ">=4.0" },
     { name = "pytaglib", marker = "extra == 'audio'", specifier = ">=2.0.0" },
-    { name = "python-frontmatter", marker = "extra == 'markdown'", specifier = ">=1.0" },
+    { name = "pyyaml", marker = "extra == 'markdown'", specifier = ">=6.0" },
     { name = "rich", specifier = ">=13.4.2" },
 ]
 provides-extras = ["audio", "pdf", "office", "markdown", "all"]
@@ -184,18 +184,6 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/24/25/1de2678b631f5a49215c6c96fff41ba892b0a34df68d6d80292b1b48aa7f/pytest-9.1.1-py3-none-any.whl", hash = "sha256:37a86b45efb9a47a61a36449063e8e18d0cab3161329fc099eb21783169c4f0c", size = 386536, upload-time = "2026-06-19T10:58:31.347Z" },
 ]
 
-[[package]]
-name = "python-frontmatter"
-version = "1.3.0"
-source = { registry = "https://pypi.org/simple" }
-dependencies = [
-    { name = "pyyaml" },
-]
-sdist = { url = "https://files.pythonhosted.org/packages/9d/e8/79cbe69864d44f3b48e70ebee0a872a7d5a4e7150c9f8577ed7a5beefff0/python_frontmatter-1.3.0.tar.gz", hash = "sha256:acc73e477a568dc2a25c9e130c6c68ae8daa8c204c8f7e813db47d6a7280dcf2", size = 8322, upload-time = "2026-05-20T19:21:44.164Z" }
-wheels = [
-    { url = "https://files.pythonhosted.org/packages/a6/a3/17c284b4f4d8ad50f0f9ba70ad8fcc35c777aeafcdbbffdd91bbdc5ab379/python_frontmatter-1.3.0-py3-none-any.whl", hash = "sha256:9f7dd9260bec99044219159a329f64f039087f9d1a2124c9442556f2fe6f82ec", size = 10562, upload-time = "2026-05-20T19:21:43.323Z" },
-]
-
 [[package]]
 name = "pyyaml"
 version = "6.0.3"