diff --git a/roles/wip-upload-logs-swift/library/test-fixtures/logs/job-output.json b/roles/wip-upload-logs-swift/library/test-fixtures/logs/job-output.json
new file mode 100644
index 000000000..c8cd7e92d
--- /dev/null
+++ b/roles/wip-upload-logs-swift/library/test-fixtures/logs/job-output.json
@@ -0,0 +1 @@
+{"test": "foo"}
diff --git a/roles/wip-upload-logs-swift/library/test_zuul_swift_upload.py b/roles/wip-upload-logs-swift/library/test_zuul_swift_upload.py
index e44d599ea..ddda40c42 100644
--- a/roles/wip-upload-logs-swift/library/test_zuul_swift_upload.py
+++ b/roles/wip-upload-logs-swift/library/test_zuul_swift_upload.py
@@ -57,6 +57,7 @@ class TestFileList(unittest.TestCase):
             ('', 'application/directory', None),
             ('controller', 'application/directory', None),
             ('zuul-info', 'application/directory', None),
+            ('job-output.json', 'application/json', None),
             ('controller/subdir', 'application/directory', None),
             ('controller/compressed.gz', 'text/plain', 'gzip'),
             ('controller/journal.xz', 'text/plain', 'xz'),
@@ -76,6 +77,7 @@ class TestFileList(unittest.TestCase):
             ('logs', 'application/directory', None),
             ('logs/controller', 'application/directory', None),
             ('logs/zuul-info', 'application/directory', None),
+            ('logs/job-output.json', 'application/json', None),
             ('logs/controller/subdir', 'application/directory', None),
             ('logs/controller/compressed.gz', 'text/plain', 'gzip'),
             ('logs/controller/journal.xz', 'text/plain', 'xz'),
@@ -107,9 +109,10 @@ class TestFileList(unittest.TestCase):
             ('', 'application/directory', None),
             ('index.html', 'text/html', None),
             ('logs', 'application/directory', None),
-            ('logs/index.html', 'text/html', None),
             ('logs/controller', 'application/directory', None),
             ('logs/zuul-info', 'application/directory', None),
+            ('logs/job-output.json', 'application/json', None),
+            ('logs/index.html', 'text/html', None),
             ('logs/controller/subdir', 'application/directory', None),
             ('logs/controller/compressed.gz', 'text/plain', 'gzip'),
             ('logs/controller/journal.xz', 'text/plain', 'xz'),
@@ -154,9 +157,10 @@ class TestFileList(unittest.TestCase):
 
         self.assert_files(fl, [
             ('', 'application/directory', None),
-            ('index.html', 'text/html', None),
             ('controller', 'application/directory', None),
             ('zuul-info', 'application/directory', None),
+            ('job-output.json', 'application/json', None),
+            ('index.html', 'text/html', None),
             ('controller/subdir', 'application/directory', None),
             ('controller/compressed.gz', 'text/plain', 'gzip'),
             ('controller/journal.xz', 'text/plain', 'xz'),
diff --git a/roles/wip-upload-logs-swift/library/zuul_swift_upload.py b/roles/wip-upload-logs-swift/library/zuul_swift_upload.py
index 561e51d76..83d887975 100755
--- a/roles/wip-upload-logs-swift/library/zuul_swift_upload.py
+++ b/roles/wip-upload-logs-swift/library/zuul_swift_upload.py
@@ -392,6 +392,21 @@ class Uploader(object):
                 # No more work to do
                 return
 
+    @staticmethod
+    def _is_text_type(mimetype):
+        # We want to compress all text types.
+        if mimetype.startswith('text/'):
+            return True
+
+        # Further compress types that typically contain text but are no
+        # text sub type.
+        compress_types = [
+            'application/json',
+        ]
+        if mimetype in compress_types:
+            return True
+        return False
+
     def _post_file(self, fd):
         relative_path = os.path.join(self.prefix, fd.relative_path)
         headers = {}
@@ -404,7 +419,7 @@ class Uploader(object):
         for attempt in range(3):
             try:
                 if not fd.folder:
-                    if fd.encoding is None and fd.mimetype.startswith('text/'):
+                    if fd.encoding is None and self._is_text_type(fd.mimetype):
                         headers['content-encoding'] = 'deflate'
                         data = DeflateFilter(open(fd.full_path, 'rb'))
                     else: