diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 0024e81..a95d121 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -51,11 +51,81 @@ jobs:
           cache: "pip"
           cache-dependency-path: "pyproject.toml"
       - name: Test with pytest
-        run: hatch run pytest-ci ${{ matrix.python-version }}
-      - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v4
         env:
-          CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
+          COVERAGE_FILE: .coverage.${{ matrix.os }}.${{ matrix.python-version }}
+        run: hatch run pytest-ci ${{ matrix.python-version }}
+      - name: Upload coverage data
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-data-${{ matrix.os }}-${{ matrix.python-version }}
+          path: .coverage.${{ matrix.os }}.${{ matrix.python-version }}
+
+  coverage:
+    runs-on: ubuntu-latest
+    needs: test
+    outputs:
+      percentage: ${{ steps.percentage.outputs.percentage }}
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install Coverage.py
+        run: pipx install coverage[toml]
+      - name: Download coverage data
+        uses: actions/download-artifact@v4
+        with:
+          pattern: coverage-data-*
+          merge-multiple: true
+      - name: Combine data
+        run: coverage combine
+      - name: Output coverage percentage
+        id: percentage
+        run: |
+          coverage json
+          echo "percentage=$(jq '.totals.percent_covered_display' coverage.json)" >> $GITHUB_OUTPUT
+      - name: Save coverage report
+        run: coverage report --format=markdown >> $GITHUB_STEP_SUMMARY
+      - name: Ensure 100% coverage
+        run: coverage report --fail-under=100
+
+  coverage-badge:
+    runs-on: ubuntu-latest
+    needs: coverage
+    if: github.event_name == 'push' && github.ref_name == 'main'
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: "coverage-badge"
+      - name: Calculate badge color
+        id: color
+        run: |
+          echo "color=$(python3 -Ic 'print(
+            min(
+              color
+              for percentage, color in [
+                (100, "brightgreen"),
+                (90, "green"),
+                (70, "yellowgreen"),
+                (50, "yellow"),
+                (30, "orange"),
+                (0, "red"),
+              ]
+              if percentage >= int(${{ needs.coverage.outputs.percentage }})
+            )
+          )')" >> $GITHUB_OUTPUT
+      - name: Update JSON file
+        run: |
+          jq -n \
+            --argjson schemaVersion 1 \
+            --arg label coverage \
+            --arg message ${{ needs.coverage.outputs.percentage }}% \
+            --arg color ${{ steps.color.outputs.color }} \
+            '$ARGS.named' > coverage-badge.json
+      - name: Create commit
+        run: |
+          git config user.name 'prns'
+          git config user.email '77806190+prnss@users.noreply.github.com'
+          git commit -am "Update coverage" && git push || true
 
   build:
     runs-on: ubuntu-latest
@@ -77,6 +147,7 @@ jobs:
     needs:
       - lint
       - test
+      - coverage
       - build
     if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
     environment: pypi-publish
@@ -120,6 +191,7 @@ jobs:
     needs:
       - lint
       - test
+      - coverage
       - build
       - lint-spec-parser
     if: always()
diff --git a/README.md b/README.md
index ac39377..6fb708c 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@ HTML generator using pure Python.
 [![PyPI - Python Version](https://img.shields.io/pypi/pyversions/domify)](https://pypi.org/project/domify/)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Tests status](https://img.shields.io/github/actions/workflow/status/Parnassius/domify/main.yml?branch=main&label=tests)](https://github.com/Parnassius/domify/actions/workflows/main.yml)
-[![Codecov](https://img.shields.io/codecov/c/gh/Parnassius/domify/main?token=8HPKPH5U3K)](https://codecov.io/gh/Parnassius/domify)
+![Coverage](https://img.shields.io/endpoint?url=https%3A%2F%2Fraw.githubusercontent.com%2FParnassius%2Fdomify%2Fcoverage-badge%2Fcoverage-badge.json)
 [![PyPI - License](https://img.shields.io/pypi/l/domify)](https://github.com/Parnassius/domify/blob/main/LICENSE)
 
 Simple example:
diff --git a/pyproject.toml b/pyproject.toml
index eee8b8c..4c3dbdf 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -64,7 +64,7 @@ darglint = "hatch run lint:darglint domify tests -v 2 {args}"
 mypy = "hatch run lint:mypy domify tests {args}"
 ruff = "hatch run lint:ruff domify tests {args}"
 pytest = "hatch run test:pytest {args}"
-pytest-ci = "hatch run +py={args} test:pytest --cov --cov-report=xml"
+pytest-ci = "hatch run +py={args} test:pytest --cov"
 all = ["format", "darglint", "mypy", "ruff", "pytest"]
 
 _check_uncommited_changes = [
@@ -118,6 +118,7 @@ exclude_lines = [
 ]
 
 [tool.coverage.run]
+relative_files = true
 source = ["domify"]
 omit = ["domify/__about__.py"]