diff --git a/web/clitools/searchdupes.php b/web/clitools/searchdupes.php
new file mode 100755
index 0000000..5b5fc80
--- /dev/null
+++ b/web/clitools/searchdupes.php
@@ -0,0 +1,195 @@
+#!/usr/bin/php
+<?php
+
+/*
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+define('N',"\n");
+define('SNAME',basename(__FILE__));
+define('CONFIGFP',__DIR__.'/../../conf/mustard.ini');
+
+$help='SYNOPSYS
+ '.SNAME.' [options]
+DESCRIPTION
+  This is a script to check the «Instances» table of mastostart database for
+ multiple records with the same URI value.
+OPTIONS
+ -d, --delete
+   For each URI with multiple records, give the possibility to interactively
+  choose which record to keep, and delete the others (default); or to
+  automatically keep the record with the lowest ID and delete the others
+  (see below).
+ -I, --nonint
+   Disable interactive mode.
+ -h, --help
+  Show this help text and exit.'.N;
+
+$opts=[
+	'delete'=>false,
+	'interactive'=>true
+];
+
+for ($i=1; $i<$argc; $i++) {
+	if ($argv[$i]=='-h' || $argv[$i]=='--help') {
+		mexit($help,0);
+	} elseif ($argv[$i]=='-d' || $argv[$i]=='--delete') {
+		$opts['delete']=true;
+	} elseif ($argv[$i]=='-I' || $argv[$i]=='--nonint') {
+		$opts['interactive']=false;
+	} else {
+		mexit('Don’t know how to interpret «'.$argv[$i].'», please read the help text using «-h» or «--help» option.'.N,1);
+	}
+}
+
+use function mysqli_real_escape_string as myesc;
+
+function mexit($msg,$code) {
+	global $link;
+	if (isset($link)) mysqli_close($link);
+	if ($code>0)
+		fwrite(STDERR,$msg);
+	else
+		echo($msg);
+	exit($code);
+}
+
+$iniarr=@parse_ini_file(CONFIGFP)
+	or mexit('Could not open config file «'.CONFIGFP.'».'.N,1);
+
+try { $link=mysqli_connect($iniarr['db_host'],$iniarr['db_admin_name'],$iniarr['db_admin_password'],$iniarr['db_name'],$iniarr['db_port'],$iniarr['db_socket']); }
+catch (Exception $error) { mexit('Could not connect to mysql server: '.$error->getMessage().' (error code: '.$error->getCode().').'.N,1); }
+mysqli_set_charset($link,'utf8mb4');
+
+function myq(&$l,$q) {
+	try {
+		$res=mysqli_query($l,$q);
+	}
+	catch (Exception $e) {
+		echo('query «'.$q.'» failed: '.$e->getMessage().' (error code: '.$e->getCode().').'.N);
+		exit(3);
+	}
+	return($res);
+}
+
+$insts=[];
+$res=mysqli_query($link,'SELECT * FROM Instances');
+while ($row=mysqli_fetch_assoc($res))
+	$insts[$row['URI']][]=$row;
+
+//ID: 83; FirstSeen: 1602617889; IsMastodon: 0; Dead: 0; New: 0; Good: 0; Chosen: 0; Priority: NULL; Visible: 0; Noxious: 0; NoxReason: NULL; NoxLastModTS: NULL; URI: ambrosia.cafe; Title: ambrosia café; ShortDesc: NULL; LongDesc: Pleroma: An efficient and flexible fediverse server; OurDesc: NULL; OurDescEN: NULL; LocalityID: NULL; OurLangsLock: 0; Email: admin@ambrosia.cafe; Software: NULL; Version: 2.7.2 (compatible; Pleroma 2.4.2); UserCount: 3; StatusCount: 299; DomainCount: 2900; ActiveUsersMonth: NULL; ActiveUsersHalfYear: NULL; Thumb: https://ambrosia.cafe/instance/thumbnail.jpeg; RegOpen: 0; RegReqApproval: 0; MaxTootChars: 5000; AdmAccount: NULL; AdmDisplayName: NULL; AdmCreatedAt: NULL; AdmNote: NULL; AdmURL: NULL; AdmAvatar: NULL; AdmHeader: NULL; LastCheckOk: 0; GuestID: NULL; LastGuestEdit: NULL; InsertTS: NULL; RPos: 4291;
+
+$tot=0;
+foreach ($insts as $uri=>$rows)
+	if (count($rows)>1) $tot++;
+
+if ($tot>0 && $opts['delete']) {
+	$i=0;
+	foreach ($insts as $uri=>$rows) {
+		$cr=count($rows);
+		if ($cr>1) {
+			$i++;
+			echo('<<< '.$i.'/'.$tot.': '.$uri.' ('.$cr.' records) >>>'.N.N);
+			$buff=[];
+			foreach ($rows as $row) {
+				$row['FirstSeen']=utstd($row['FirstSeen']);
+				$row['NoxLastModTS']=utstd($row['NoxLastModTS']);
+				$row['AdmCreatedAt']=utstd($row['AdmCreatedAt']);
+				$row['LastGuestEdit']=utstd($row['LastGuestEdit']);
+				$row['InsertTS']=utstd($row['InsertTS']);
+				$out='';
+				foreach ($row as $key=>$val)
+					$out.=$key.': '.pr($val).'; ';
+				$out=substr($out,0,-2);
+				//echo($out.N.N);
+				$buff[$row['ID']]=['id'=>$row['ID'],'row'=>$out];
+			}
+			asort($buff);
+			$ii=0;
+			$recs=[];
+			foreach ($buff as $rec) {
+				$ii++;
+				$recs[$ii]=$rec;
+				echo($ii.': '.$rec['row'].N.N);
+			}
+			if ($opts['interactive']) {
+				$ans=[];
+				for ($iii=1; $iii<=$ii; $iii++)
+					$ans[]=$iii;
+				$ans[]='e';
+				$inp=null;
+				while (!in_array($inp,$ans)) {
+					echo('Which one do you want to keep? ['.implode('/',$ans).'] ');
+					$inp=strtolower(trim(fgets(STDIN)));
+				}
+			} else {
+				$inp=1;
+			}
+			if ($inp=='e') {
+				mexit('Ok, bye :-)'.N,0);
+			} else {
+				$inp+=0;
+				echo(N.'Ok, i’ll keep the record with ID='.$recs[$inp]['id'].N);
+				foreach ($recs as $key=>$rec) {
+					if ($key!=$inp) {
+						echo('Deleting record with ID='.$rec['id'].' ...'.N);
+						myq($link,'DELETE FROM Instances WHERE ID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from Instances table.'.N);
+						myq($link,'DELETE FROM InstActivity WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstActivity table.'.N);
+						myq($link,'DELETE FROM InstChecks WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstChecks table.'.N);
+						myq($link,'DELETE FROM InstFinancing WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstFinancing table.'.N);
+						myq($link,'DELETE FROM InstLangs WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstLangs table.'.N);
+						myq($link,'DELETE FROM InstOurLangs WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstOurLangs table.'.N);
+						myq($link,'DELETE FROM InstPolicies WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstPolicies table.'.N);
+						myq($link,'DELETE FROM InstTags WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstTags table.'.N);
+						myq($link,'DELETE FROM InstTrends WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from InstTrends table.'.N);
+						$users=myq($link,'SELECT ID FROM Users WHERE InstID='.$rec['id']);
+						$iii=0;
+						while ($user=mysqli_fetch_assoc($users)) {
+							myq($link,'DELETE FROM UsersFields WHERE UserID='.$user['ID']);
+							$iii+=mysqli_affected_rows($link);
+						}
+						echo('Deleted '.$iii.' records from UsersFields table.'.N);
+						myq($link,'DELETE FROM Users WHERE InstID='.$rec['id']);
+						echo('Deleted '.mysqli_affected_rows($link).' records from Users table.'.N);
+					}
+				}
+				echo(N);
+			}
+		}
+	}
+}
+echo('Total dupes: '.$tot.N);
+mysqli_close($link);
+exit(0);
+
+function utstd($val) {
+	if (is_null($val)) return(null);
+	$val=round($val);
+	return(date('Y-m-d H:i:s',$val));
+}
+function pr($val) {
+	if (is_null($val)) return('NULL');
+	return($val);
+}
+
+?>