diff --git a/swh/lister/github/generate_tasks.py b/swh/lister/github/generate_tasks.py
new file mode 100644
index 0000000..1184b73
--- /dev/null
+++ b/swh/lister/github/generate_tasks.py
@@ -0,0 +1,111 @@
+# Copyright (C) 2015  The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+
+import psycopg2
+import pickle
+
+
+def list_imported_repos(swh_db):
+    """List all the repositories that have been successfully imported in Software
+    Heritage.
+    """
+    query = """
+    select o.url
+    from origin o
+    left join fetch_history fh
+    on o.id = fh.origin
+    where
+        fh.status = true and
+        o.url ~~ 'https://github.com/%'
+    """
+
+    cur = swh_db.cursor()
+    cur.execute(query)
+    res = cur.fetchall()
+    cur.close()
+    return set('/'.join(repo.rsplit('/', 2)[-2:]) for (repo,) in res)
+
+
+def list_fetched_repos(ghlister_db):
+    """List all the repositories that have been successfully fetched from GitHub.
+    """
+    query = """
+    select r.full_name
+    from crawl_history ch
+    left join repos r
+    on ch.repo = r.id
+    where
+        ch.status = true and
+        r.fork = false
+    """
+
+    cur = ghlister_db.cursor()
+    cur.execute(query)
+    res = cur.fetchall()
+    cur.close()
+    return set(repo for (repo,) in res)
+
+
+def list_missing_repos():
+    """List all the repositories that have not yet been imported successfully."""
+    swh_db = psycopg2.connect('service=softwareheritage')
+    imported_repos = list_imported_repos(swh_db)
+    swh_db.close()
+
+    ghlister_db = psycopg2.connect('service=lister-github')
+    fetched_repos = list_fetched_repos(ghlister_db)
+    ghlister_db.close()
+
+    return fetched_repos - imported_repos
+
+
+def generate_tasks(checkpoint_file='repos', checkpoint_every=100000):
+    """Generate the Celery tasks to fetch all the missing repositories.
+
+    Checkpoint the missing repositories every checkpoint_every tasks sent, in a
+    pickle file called checkpoint_file.
+
+    If the checkpoint file exists, we do not call the database again but load
+    from the file.
+    """
+    import swh.loader.git.tasks
+    from swh.core.worker import app  # flake8: noqa for side effects
+
+    def checkpoint_repos(repos, checkpoint=checkpoint_file):
+        tmp = '.%s.tmp' % checkpoint
+        with open(tmp, 'wb') as f:
+            pickle.dump(repos, f)
+
+        os.rename(tmp, checkpoint)
+
+    def fetch_checkpoint_repos(checkpoint=checkpoint_file):
+        with open(checkpoint, 'rb') as f:
+            return pickle.load(f)
+
+    repos = set()
+
+    if not os.path.exists(checkpoint_file):
+        repos = list_missing_repos()
+        checkpoint_repos(repos)
+    else:
+        repos = fetch_checkpoint_repos()
+
+    task = app.tasks['swh.loader.git.tasks.LoadGitHubRepository']
+
+    ctr = 0
+    while True:
+        try:
+            repo = repos.pop()
+        except KeyError:
+            break
+
+        task.delay(repo)
+
+        ctr += 1
+        if ctr >= checkpoint_every:
+            ctr = 0
+            checkpoint_repos(repos)
+
+    os.unlink(checkpoint)