diff --git a/bin/checksum.pl b/bin/checksum.pl
new file mode 100644
index 0000000..dffa986
--- /dev/null
+++ b/bin/checksum.pl
@@ -0,0 +1,112 @@
+use strict;
+use warnings;
+use v5.36;
+
+use Getopt::Long;
+use Digest::file qw< digest_file_hex >;
+use MetaCPAN::Logger qw< :log :dlog >;
+
+use MetaCPAN::ES;
+use MetaCPAN::Ingest qw< cpan_dir >;
+
+# args
+my $limit = 1000;
+my $dry_run;
+GetOptions(
+    "limit=i" => \$limit,
+    "dry_run" => \$dry_run,
+);
+
+# setup
+my $es = MetaCPAN::ES->new( type => "release" );
+my $bulk;
+$bulk = $es->bulk() unless $dry_run;
+
+log_warn {"--- DRY-RUN ---"} if $dry_run;
+log_info {"Searching for releases missing checksums"};
+
+my $scroll = $es->scroll(
+    scroll => '10m',
+    body   => {
+        query => {
+            not => {
+                exists => {
+                    field => "checksum_md5"
+                }
+            }
+        }
+    },
+    fields => [qw< id name download_url >],
+);
+
+log_warn { "Found " . $scroll->total . " releases" };
+log_warn { "Limit is " . $limit };
+
+my $count = 0;
+
+while ( my $p = $scroll->next ) {
+    if ( $limit >= 0 and $count++ >= $limit ) {
+        log_info {"Max number of changes reached."};
+        last;
+    }
+
+    log_info { "Adding checksums for " . $p->{fields}{name}[0] };
+
+    if ( my $download_url = $p->{fields}{download_url} ) {
+        my $file
+            = cpan_dir . "/authors" . $p->{fields}{download_url}[0]
+            =~ s/^.*authors//r;
+        my $checksum_md5    = digest_file_hex( $file, 'MD5' );
+        my $checksum_sha256 = digest_file_hex( $file, 'SHA-256' );
+
+        if ($dry_run) {
+            log_info { "--- MD5: " . $checksum_md5 };
+            log_info { "--- SHA256: " . $checksum_sha256 };
+        }
+        else {
+            $bulk->update( {
+                id  => $p->{_id},
+                doc => {
+                    checksum_md5    => $checksum_md5,
+                    checksum_sha256 => $checksum_sha256
+                },
+                doc_as_upsert => 1,
+            } );
+        }
+    }
+    else {
+        log_info { $p->{fields}{name}[0] . " is missing a download_url" };
+    }
+}
+
+$bulk->flush unless $dry_run;
+
+log_info {'Finished adding checksums'};
+
+1;
+
+__END__
+
+=pod
+
+=head1 SYNOPSIS
+
+ # bin/metacpan checksum --[no-]dry_run --limit X
+
+=head1 DESCRIPTION
+
+Backfill checksums for releases
+
+=head2 dry_run
+
+Don't update - just show what would have been updated (default)
+
+=head2 no-dry_run
+
+Update records
+
+=head2 limit
+
+Max number of records to update. default=1000, for unlimited set to -1
+
+=cut