diff --git a/.github/workflows/ci-test.yml b/.github/workflows/ci-test.yml
index 409701cc..b22b613a 100644
--- a/.github/workflows/ci-test.yml
+++ b/.github/workflows/ci-test.yml
@@ -115,7 +115,7 @@ jobs:
 
       - name: Unit tests (local)
         if: matrix.backend == 'local'
-        run: pytest -m "not mongo and not sql and not redis and not s3" --cov=cachier --cov-report=term --cov-report=xml:cov.xml
+        run: pytest -m "not mongo and not sql and not redis and not s3" -n auto --cov=cachier --cov-report=term --cov-report=xml:cov.xml
 
       - name: Setup docker (missing on MacOS)
         if: runner.os == 'macOS' && matrix.backend == 'mongodb'
@@ -148,7 +148,7 @@ jobs:
 
       - name: Unit tests (DB)
         if: matrix.backend == 'mongodb'
-        run: pytest -m "mongo" --cov=cachier --cov-report=term --cov-report=xml:cov.xml
+        run: pytest -m "mongo" -n auto --cov=cachier --cov-report=term --cov-report=xml:cov.xml
       - name: Speed eval
         run: python tests/speed_eval.py
 
@@ -169,7 +169,7 @@ jobs:
         if: matrix.backend == 'postgres'
         env:
           SQLALCHEMY_DATABASE_URL: postgresql+psycopg://testuser:testpass@localhost:5432/testdb
-        run: pytest -m sql --cov=cachier --cov-report=term --cov-report=xml:cov.xml
+        run: pytest -m sql -n auto --cov=cachier --cov-report=term --cov-report=xml:cov.xml
 
       - name: Start Redis in docker
         if: matrix.backend == 'redis'
@@ -183,11 +183,11 @@ jobs:
 
       - name: Unit tests (Redis)
         if: matrix.backend == 'redis'
-        run: pytest -m redis --cov=cachier --cov-report=term --cov-report=xml:cov.xml
+        run: pytest -m redis -n auto --cov=cachier --cov-report=term --cov-report=xml:cov.xml
 
       - name: Unit tests (S3)
         if: matrix.backend == 's3'
-        run: pytest -m s3 --cov=cachier --cov-report=term --cov-report=xml:cov.xml
+        run: pytest -m s3 -n auto --cov=cachier --cov-report=term --cov-report=xml:cov.xml
 
       - name: Upload coverage to Codecov (non PRs)
         continue-on-error: true
diff --git a/tests/README.md b/tests/README.md
index acb8214f..de92da27 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -339,24 +339,26 @@ The CI pipeline runs a matrix job per backend. Each backend uses the commands be
 
 ```bash
 # Local backends (memory, pickle, and other non-external tests)
-pytest -m "not mongo and not sql and not redis and not s3"
+pytest -m "not mongo and not sql and not redis and not s3" -n auto
 
 # MongoDB backend
-pytest -m mongo
+pytest -m mongo -n auto
 
 # PostgreSQL/SQL backend
-pytest -m sql
+pytest -m sql -n auto
 
 # Redis backend
-pytest -m redis
+pytest -m redis -n auto
 
 # S3 backend
-pytest -m s3
+pytest -m s3 -n auto
 ```
 
-Note: local tests do not use `pytest-xdist` (`-n`) in CI. External backends
-(MongoDB, PostgreSQL, Redis, S3) each run in their own isolated matrix job with
-the corresponding Docker service started beforehand.
+All backends use `pytest-xdist` (`-n auto`) in CI for parallel test execution.
+Each backend runs in its own isolated matrix job with the corresponding Docker
+service started beforehand. Per-worker isolation is handled automatically by
+the fixtures in `conftest.py` (separate cache directories for pickle/maxage
+tests, separate PostgreSQL schemas for SQL tests).
 
 ### Environment Variables
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 57d5dba0..9f0d47f1 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -55,16 +55,7 @@ def inject_worker_schema_for_sql_tests(monkeypatch, request):
 
         # Rebuild the URL with updated query parameters
         new_query = urlencode(query_params, doseq=True)
-        new_url = urlunparse(
-            (
-                parsed.scheme,
-                parsed.netloc,
-                parsed.path,
-                parsed.params,
-                new_query,
-                parsed.fragment
-            )
-        )
+        new_url = urlunparse((parsed.scheme, parsed.netloc, parsed.path, parsed.params, new_query, parsed.fragment))
 
         # Override both the environment variable and the module constant
         monkeypatch.setenv("SQLALCHEMY_DATABASE_URL", new_url)
@@ -155,14 +146,7 @@ def cleanup_test_schemas(request):
                 # Rebuild clean URL
                 clean_query = urlencode(query_params, doseq=True) if query_params else ""
                 clean_url = urlunparse(
-                    (
-                        parsed.scheme,
-                        parsed.netloc,
-                        parsed.path,
-                        parsed.params,
-                        clean_query,
-                        parsed.fragment
-                    )
+                    (parsed.scheme, parsed.netloc, parsed.path, parsed.params, clean_query, parsed.fragment)
                 )
 
                 engine = create_engine(clean_url)