diff --git a/hgext3rd/crdump.py b/hgext3rd/crdump.py
new file mode 100644
--- /dev/null
+++ b/hgext3rd/crdump.py
@@ -0,0 +1,187 @@
+# crdump.py - dump changesets information to filesystem
+#
+from __future__ import absolute_import
+
+import json, re, shutil, tempfile
+from os import path
+
+from mercurial import (
+    error,
+    extensions,
+    phases,
+    registrar,
+    scmutil,
+)
+
+from mercurial.i18n import _
+from mercurial.node import hex
+
+DIFFERENTIAL_REGEX = re.compile(
+    'Differential Revision: http.+?/'  # Line start, URL
+    'D(?P<id>[0-9]+)',  # Differential ID, just numeric part
+    flags = re.LOCALE
+)
+cmdtable = {}
+command = registrar.command(cmdtable)
+
+@command('debugcrdump', [
+         ('r', 'rev', [], _("revisions to dump")),
+         # We use 1<<15 for "as much context as possible"
+         ('U', 'unified',
+          1 << 15, _('number of lines of context to show'), _('NUM')),
+         ],
+         _('hg debugcrdump [OPTION]... [-r] [REV]'))
+def crdump(ui, repo, *revs, **opts):
+    """
+    Dump the info about the revisions in format that's friendly for sending the
+    patches for code review.
+
+    The output is a JSON list with dictionary for each specified revision: ::
+
+        {
+          "output_directory": an output directory for all temporary files
+          "commits": [
+          {
+            "node": commit hash,
+            "date": date in format [unixtime, timezone offset],
+            "desc": commit message,
+            "patch_file": path to file containing patch in unified diff format
+                          relative to output_directory,
+            "files": list of files touched by commit,
+            "binary_files": [
+              {
+                "filename": path to file relative to repo root,
+                "old_file": path to file (relative to output_directory) with
+                            a dump of the old version of the file,
+                "new_file": path to file (relative to output_directory) with
+                            a dump of the newversion of the file,
+              },
+              ...
+            ],
+            "user": commit author,
+            "p1": {
+              "node": hash,
+              "differential_revision": xxxx
+            },
+            "public_base": {
+              "node": public base commit hash,
+              "svnrev": svn revision of public base (if hgsvn repo),
+            }
+          },
+          ...
+          ]
+        }
+    """
+
+    revs = list(revs)
+    revs.extend(opts['rev'])
+
+    if not revs:
+        raise error.Abort(_('revisions must be specified'))
+    revs = scmutil.revrange(repo, revs)
+
+    if 'unified' in opts:
+        contextlines = opts['unified']
+
+    cdata = []
+    outdir = tempfile.mkdtemp(suffix='hg.crdump')
+    try:
+        for rev in revs:
+            ctx = repo[rev]
+            rdata = {
+                'node': hex(ctx.node()),
+                'date': map(int, ctx.date()),
+                'desc': ctx.description(),
+                'files': ctx.files(),
+                'p1': {
+                    'node': ctx.parents()[0].hex(),
+                },
+                'user': ctx.user(),
+            }
+            if ctx.parents()[0].phase() != phases.public:
+                # we need this only if parent is in the same draft stack
+                rdata['p1']['differential_revision'] = \
+                    phabricatorrevision(ctx.parents()[0])
+
+            pbctx = publicbase(repo, ctx)
+            if pbctx:
+                rdata['public_base'] = {
+                    'node': hex(pbctx.node()),
+                }
+                try:
+                    hgsubversion = extensions.find('hgsubversion')
+                    svnrev = hgsubversion.util.getsvnrev(pbctx)
+                    # There are no abstractions in hgsubversion for doing
+                    # it see hgsubversion/svncommands.py:267
+                    rdata['public_base']['svnrev'] = \
+                        svnrev.split('@')[1] if svnrev else None
+                except KeyError:
+                    pass
+            rdata['patch_file'] = dumppatch(ui, repo, ctx, outdir, contextlines)
+            rdata['binary_files'] = dumpbinaryfiles(ui, repo, ctx, outdir)
+            cdata.append(rdata)
+
+        ui.write(json.dumps({
+            'output_directory': outdir,
+            'commits': cdata,
+        }, sort_keys=True, indent=4, separators=(',', ': ')))
+        ui.write('\n')
+    except Exception as e:
+        shutil.rmtree(outdir)
+        raise e
+
+def dumppatch(ui, repo, ctx, outdir, contextlines):
+    chunks = ctx.diff(git=True, unified=contextlines, binary=False)
+    patchfile = '%s.patch' % hex(ctx.node())
+    with open(path.join(outdir, patchfile), 'w') as f:
+        for chunk in chunks:
+            f.write(chunk)
+    return patchfile
+
+def dumpfctx(outdir, fctx):
+    outfile = '%s' % hex(fctx.filenode())
+    writepath = path.join(outdir, outfile)
+    if not path.isfile(writepath):
+        with open(writepath, 'w') as f:
+            f.write(fctx.data())
+    return outfile
+
+def dumpbinaryfiles(ui, repo, ctx, outdir):
+    binaryfiles = []
+    pctx = ctx.parents()[0]
+    for fname in ctx.files():
+        oldfile = newfile = None
+        dump = False
+
+        fctx = ctx[fname] if fname in ctx else None
+        pfctx = pctx[fname] if fname in pctx else None
+
+        # if one of the versions is binary file the whole change will show
+        # up as binary in diff output so we need to dump both versions
+        if fctx and fctx.isbinary():
+            dump = True
+        if pfctx and pfctx.isbinary():
+            dump = True
+
+        if dump:
+            if fctx:
+                newfile = dumpfctx(outdir, fctx)
+            if pfctx:
+                oldfile = dumpfctx(outdir, pfctx)
+            binaryfiles.append({
+                'file_name': fname,
+                'old_file': oldfile,
+                'new_file': newfile,
+            })
+
+    return binaryfiles
+
+def phabricatorrevision(ctx):
+    match = DIFFERENTIAL_REGEX.search(ctx.description())
+    return match.group(1) if match else ''
+
+def publicbase(repo, ctx):
+    base = repo.revs('last(::%d & public())', ctx.rev())
+    if len(base):
+        return repo[base.first()]
+    return None
diff --git a/tests/test-crdump.t b/tests/test-crdump.t
new file mode 100644
--- /dev/null
+++ b/tests/test-crdump.t
@@ -0,0 +1,226 @@
+  $ cat >> $HGRCPATH << EOF
+  > [extensions]
+  > drawdag=$RUNTESTDIR/drawdag.py
+  > crdump=$TESTDIR/../hgext3rd/crdump.py
+  > EOF
+
+Create repo
+  $ mkdir repo
+  $ cd repo
+  $ hg init
+  $ echo A > a
+  $ echo -e "A\0" > bin1
+  $ hg addremove
+  adding a
+  adding bin1
+  $ hg commit -m a
+  $ hg phase -p .
+
+  $ printf "A\nB\nC\nD\nE\nF\n" > a
+  $ echo -e "a\0b" > bin1
+  $ echo -e "b\0" > bin2
+  $ hg addremove
+  adding bin2
+  $ hg commit -m "b
+  > Differential Revision: https://phabricator.facebook.com/D123"
+
+  $ echo G >> a
+  $ echo C > c
+  $ rm bin2
+  $ echo x > bin1
+  $ hg addremove
+  removing bin2
+  adding c
+  $ hg commit -m c
+
+Test basic dump of two commits
+
+  $ hg debugcrdump -U 1 -r ".^^::." --traceback| tee ../json_output
+  {
+      "commits": [
+          {
+              "binary_files": [
+                  {
+                      "file_name": "bin1",
+                      "new_file": "23c26c825bddcb198e701c6f7043a4e35dcb8b97",
+                      "old_file": null
+                  }
+              ],
+              "date": [
+                  0,
+                  0
+              ],
+              "desc": "a",
+              "files": [
+                  "a",
+                  "bin1"
+              ],
+              "node": "65d913976cc18347138f7b9f5186010d39b39b0f",
+              "p1": {
+                  "node": "0000000000000000000000000000000000000000"
+              },
+              "patch_file": "65d913976cc18347138f7b9f5186010d39b39b0f.patch",
+              "public_base": {
+                  "node": "65d913976cc18347138f7b9f5186010d39b39b0f"
+              },
+              "user": "test"
+          },
+          {
+              "binary_files": [
+                  {
+                      "file_name": "bin1",
+                      "new_file": "5f54dc7f5b744f0bf88fcfe31eaba3cabc7a5f0c",
+                      "old_file": "23c26c825bddcb198e701c6f7043a4e35dcb8b97"
+                  },
+                  {
+                      "file_name": "bin2",
+                      "new_file": "31f7b4d23cf93fd41972d0a879086e900cbf06c9",
+                      "old_file": null
+                  }
+              ],
+              "date": [
+                  0,
+                  0
+              ],
+              "desc": "b\nDifferential Revision: https://phabricator.facebook.com/D123",
+              "files": [
+                  "a",
+                  "bin1",
+                  "bin2"
+              ],
+              "node": "6370cd64643d547e11c6bc91920bca7b44ea21b5",
+              "p1": {
+                  "node": "65d913976cc18347138f7b9f5186010d39b39b0f"
+              },
+              "patch_file": "6370cd64643d547e11c6bc91920bca7b44ea21b5.patch",
+              "public_base": {
+                  "node": "65d913976cc18347138f7b9f5186010d39b39b0f"
+              },
+              "user": "test"
+          },
+          {
+              "binary_files": [
+                  {
+                      "file_name": "bin1",
+                      "new_file": "4281f31b8cfa1376dc036a729c4118cd192db663",
+                      "old_file": "5f54dc7f5b744f0bf88fcfe31eaba3cabc7a5f0c"
+                  },
+                  {
+                      "file_name": "bin2",
+                      "new_file": null,
+                      "old_file": "31f7b4d23cf93fd41972d0a879086e900cbf06c9"
+                  }
+              ],
+              "date": [
+                  0,
+                  0
+              ],
+              "desc": "c",
+              "files": [
+                  "a",
+                  "bin1",
+                  "bin2",
+                  "c"
+              ],
+              "node": "c2c1919228a86d876dbb46befd0e0433c62a9f5f",
+              "p1": {
+                  "differential_revision": "123",
+                  "node": "6370cd64643d547e11c6bc91920bca7b44ea21b5"
+              },
+              "patch_file": "c2c1919228a86d876dbb46befd0e0433c62a9f5f.patch",
+              "public_base": {
+                  "node": "65d913976cc18347138f7b9f5186010d39b39b0f"
+              },
+              "user": "test"
+          }
+      ],
+      "output_directory": "*" (glob)
+  }
+
+  >>> import json
+  >>> from os import path
+  >>> with open("../json_output") as f:
+  ...     data = json.loads(f.read())
+  ...     outdir = data['output_directory']
+  ...     for commit in data['commits']:
+  ...         print "#### commit %s" % commit['node']
+  ...         print open(path.join(outdir, commit['patch_file'])).read()
+  ...         for binfile in commit['binary_files']:
+  ...             print "######## file %s" % binfile['file_name']
+  ...             if binfile['old_file'] is not None:
+  ...                 print "######## old"
+  ...                 print open(path.join(outdir, binfile['old_file'])).read().encode('hex')
+  ...             if binfile['new_file'] is not None:
+  ...                 print "######## new"
+  ...                 print open(path.join(outdir, binfile['new_file'])).read().encode('hex')
+  ...     import shutil
+  ...     shutil.rmtree(outdir)
+  #### commit 65d913976cc18347138f7b9f5186010d39b39b0f
+  diff --git a/a b/a
+  new file mode 100644
+  --- /dev/null
+  +++ b/a
+  @@ -0,0 +1,1 @@
+  +A
+  diff --git a/bin1 b/bin1
+  new file mode 100644
+  Binary file bin1 has changed
+  
+  ######## file bin1
+  ######## new
+  41000a
+  #### commit 6370cd64643d547e11c6bc91920bca7b44ea21b5
+  diff --git a/a b/a
+  --- a/a
+  +++ b/a
+  @@ -1,1 +1,6 @@
+   A
+  +B
+  +C
+  +D
+  +E
+  +F
+  diff --git a/bin1 b/bin1
+  Binary file bin1 has changed
+  diff --git a/bin2 b/bin2
+  new file mode 100644
+  Binary file bin2 has changed
+  
+  ######## file bin1
+  ######## old
+  41000a
+  ######## new
+  6100620a
+  ######## file bin2
+  ######## new
+  62000a
+  #### commit c2c1919228a86d876dbb46befd0e0433c62a9f5f
+  diff --git a/a b/a
+  --- a/a
+  +++ b/a
+  @@ -6,1 +6,2 @@
+   F
+  +G
+  diff --git a/bin1 b/bin1
+  Binary file bin1 has changed
+  diff --git a/bin2 b/bin2
+  deleted file mode 100644
+  Binary file bin2 has changed
+  diff --git a/c b/c
+  new file mode 100644
+  --- /dev/null
+  +++ b/c
+  @@ -0,0 +1,1 @@
+  +C
+  
+  ######## file bin1
+  ######## old
+  6100620a
+  ######## new
+  780a
+  ######## file bin2
+  ######## old
+  62000a
+
+
+