diff --git a/fsspec/caching.py b/fsspec/caching.py
index 5a9f75be8..e38782780 100644
--- a/fsspec/caching.py
+++ b/fsspec/caching.py
@@ -370,6 +370,16 @@ def __len__(self):
         return len(self.cache)
 
 
+class AllBytes(object):
+    """Cache entire contents of the file"""
+
+    def __init__(self, data):
+        self.data = data
+
+    def _fetch(self, start, end):
+        return self.data[start:end]
+
+
 caches = {
     "none": BaseCache,
     "mmap": MMapCache,
diff --git a/fsspec/implementations/http.py b/fsspec/implementations/http.py
index d3ef0a638..75fbff0b6 100644
--- a/fsspec/implementations/http.py
+++ b/fsspec/implementations/http.py
@@ -6,6 +6,7 @@
 from fsspec import AbstractFileSystem
 from fsspec.spec import AbstractBufferedFile
 from fsspec.utils import tokenize, DEFAULT_BLOCK_SIZE
+from ..caching import AllBytes
 
 # https://stackoverflow.com/a/15926317/3821154
 ex = re.compile(r"""<a\s+(?:[^>]*?\s+)?href=(["'])(.*?)\1""")
@@ -359,13 +360,3 @@ def file_size(url, session=None, size_policy="head", **kwargs):
         return int(r.headers["Content-Length"])
     elif "Content-Range" in r.headers:
         return int(r.headers["Content-Range"].split("/")[1])
-
-
-class AllBytes(object):
-    """Cache entire contents of a remote URL"""
-
-    def __init__(self, data):
-        self.data = data
-
-    def _fetch(self, start, end):
-        return self.data[start:end]
diff --git a/fsspec/registry.py b/fsspec/registry.py
index 1536668e1..3f401061c 100644
--- a/fsspec/registry.py
+++ b/fsspec/registry.py
@@ -12,6 +12,13 @@
 known_implementations = {
     "file": {"class": "fsspec.implementations.local.LocalFileSystem"},
     "memory": {"class": "fsspec.implementations.memory.MemoryFileSystem"},
+    "dropbox": {
+        "class": "dropboxdrivefs.DropboxDriveFileSystem",
+        "err": (
+            'DropboxFileSystem requires "dropboxdrivefs",'
+            '"requests" and "dropbox" to be installed'
+        ),
+    },
     "http": {
         "class": "fsspec.implementations.http.HTTPFileSystem",
         "err": 'HTTPFileSystem requires "requests" to be installed',