diff --git a/fn/auth.php b/fn/auth.php
index fd3d48f..240f8ea 100644
--- a/fn/auth.php
+++ b/fn/auth.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 const USERNAME_REGEX = '^.{1,1024}$';
 const PASSWORD_REGEX = '^(?=.*[\p{Ll}])(?=.*[\p{Lu}])(?=.*[\p{N}]).{8,1024}|.{10,1024}$';
diff --git a/fn/common.php b/fn/common.php
index 2ce54ca..bb20853 100644
--- a/fn/common.php
+++ b/fn/common.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 function output(int $code, string $msg = '', array $logs = [''], array $data = []): never {
 	http_response_code($code);
diff --git a/fn/dns.php b/fn/dns.php
index 33597b6..2d0566e 100644
--- a/fn/dns.php
+++ b/fn/dns.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 function parseZoneFile(string $zone_content, array $types, bool|string $filter_domain = false, bool $filter_include_subdomains = true): array {
 	$parsed_zone_content = [];
diff --git a/fn/ht.php b/fn/ht.php
index 75d03a3..fb4ef0b 100644
--- a/fn/ht.php
+++ b/fn/ht.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 const SUBPATH_REGEX = '^[a-z0-9-]{4,63}$';
 const ED25519_PUBKEY_REGEX = '^[a-zA-Z0-9/+]{68}$';
diff --git a/fn/ns.php b/fn/ns.php
index 953ef31..d4195db 100644
--- a/fn/ns.php
+++ b/fn/ns.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 const SOA_VALUES = [
 	'ttl' => 10800,
diff --git a/fn/reg.php b/fn/reg.php
index c49e6c4..d71b8f3 100644
--- a/fn/reg.php
+++ b/fn/reg.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 const SUBDOMAIN_REGEX = '^(?!\-)(?!..\-\-)[a-z0-9-]{4,63}(?<!\-)$';
 
diff --git a/init.php b/init.php
index 7ac3acb..33c1b82 100644
--- a/init.php
+++ b/init.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 umask(0077);
 
 set_error_handler(function ($level, $message, $file = '', $line = 0) {
diff --git a/jobs/check.php b/jobs/check.php
index fb28394..2ce0af7 100644
--- a/jobs/check.php
+++ b/jobs/check.php
@@ -1,4 +1,5 @@
-<?php // Test that the current setup is working
+<?php declare(strict_types=1);
+// Test that the current setup is working
 
 require __DIR__ . '/../init.php';
 
diff --git a/jobs/delete-old-testing.php b/jobs/delete-old-testing.php
index b295520..a8afab5 100644
--- a/jobs/delete-old-testing.php
+++ b/jobs/delete-old-testing.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 require __DIR__ . '/../init.php';
 
 const MAX_TESTING_ACCOUNT_AGE = 86400 * 10;
diff --git a/jobs/ns-sync.php b/jobs/ns-sync.php
index 9097813..afdd234 100644
--- a/jobs/ns-sync.php
+++ b/jobs/ns-sync.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 require __DIR__ . '/../init.php';
 
 foreach (query('select', 'ns-syncs') as $sync) {
diff --git a/jobs/reg-cds.php b/jobs/reg-cds.php
index 805721a..c0685b2 100644
--- a/jobs/reg-cds.php
+++ b/jobs/reg-cds.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /*
 	RFC 7344: Automating DNSSEC Delegation Trust Maintenance
 	RFC 8078: Managing DS Records from the Parent via CDS/CDNSKEY
diff --git a/jobs/reg-csync.php b/jobs/reg-csync.php
index 2878788..9d19524 100644
--- a/jobs/reg-csync.php
+++ b/jobs/reg-csync.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 /*
 	RFC 7477: Child-to-Parent Synchronization in DNS
 */
diff --git a/pages.php b/pages.php
index fadb435..a44c333 100644
--- a/pages.php
+++ b/pages.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 define('PAGES', [
 	'index' => [
diff --git a/pg-act/auth/approval.php b/pg-act/auth/approval.php
index 9a8a046..b6f568e 100644
--- a/pg-act/auth/approval.php
+++ b/pg-act/auth/approval.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if ($_SESSION['type'] !== 'testing')
 	output(403, _('This account is already approved.'));
diff --git a/pg-act/auth/login.php b/pg-act/auth/login.php
index 580f25a..77cbd39 100644
--- a/pg-act/auth/login.php
+++ b/pg-act/auth/login.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 checkPasswordFormat($_POST['password']);
 
diff --git a/pg-act/auth/logout.php b/pg-act/auth/logout.php
deleted file mode 100644
index bf11e4b..0000000
--- a/pg-act/auth/logout.php
+++ /dev/null
@@ -1,3 +0,0 @@
-<?php
-
-logout();
diff --git a/pg-act/auth/password.php b/pg-act/auth/password.php
index 6da1be9..d543a2c 100644
--- a/pg-act/auth/password.php
+++ b/pg-act/auth/password.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 checkPasswordFormat($_POST['new-password']);
 
diff --git a/pg-act/auth/register.php b/pg-act/auth/register.php
index 088fa63..4225b0f 100644
--- a/pg-act/auth/register.php
+++ b/pg-act/auth/register.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (CONF['common']['services']['auth'] !== 'enabled')
 	output(403, _('Registrations are currently closed on this installation.'));
diff --git a/pg-act/auth/unregister.php b/pg-act/auth/unregister.php
index 13b4357..9480f79 100644
--- a/pg-act/auth/unregister.php
+++ b/pg-act/auth/unregister.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (checkPassword($_SESSION['id'], $_POST['current-password']) !== true)
 	output(403, _('Wrong current password.'));
diff --git a/pg-act/auth/username.php b/pg-act/auth/username.php
index 274e818..1e9b440 100644
--- a/pg-act/auth/username.php
+++ b/pg-act/auth/username.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 checkUsernameFormat($_POST['new-username']);
 
diff --git a/pg-act/ht/add-dns.php b/pg-act/ht/add-dns.php
index 561aee0..6da0043 100644
--- a/pg-act/ht/add-dns.php
+++ b/pg-act/ht/add-dns.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $_POST['domain'] = formatDomain($_POST['domain']);
 
diff --git a/pg-act/ht/add-onion.php b/pg-act/ht/add-onion.php
index f90cc35..3d6c7ab 100644
--- a/pg-act/ht/add-onion.php
+++ b/pg-act/ht/add-onion.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (dirsStatuses('onion')[$_POST['dir']] !== false)
 	output(403, 'Wrong value for <code>dir</code>.');
diff --git a/pg-act/ht/add-subdomain.php b/pg-act/ht/add-subdomain.php
index 0a1b667..b47234c 100644
--- a/pg-act/ht/add-subdomain.php
+++ b/pg-act/ht/add-subdomain.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (dirsStatuses('subdomain')[$_POST['dir']] !== false)
 	output(403, 'Wrong value for <code>dir</code>.');
diff --git a/pg-act/ht/add-subpath.php b/pg-act/ht/add-subpath.php
index e0bb139..8a0fa27 100644
--- a/pg-act/ht/add-subpath.php
+++ b/pg-act/ht/add-subpath.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (dirsStatuses('subpath')[$_POST['dir']] !== false)
 	output(403, 'Wrong value for <code>dir</code>.');
diff --git a/pg-act/ht/del.php b/pg-act/ht/del.php
index 476cfcc..8b25929 100644
--- a/pg-act/ht/del.php
+++ b/pg-act/ht/del.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (preg_match('/^(?<type>subpath|subdomain|onion|dns):(?<address>[a-z0-9._-]{1,256})$/D', $_POST['site'], $site) !== 1)
 	output(403, 'Malformed value for <code>site</code>.');
diff --git a/pg-act/ht/keys.php b/pg-act/ht/keys.php
index 3ff46aa..2d537df 100755
--- a/pg-act/ht/keys.php
+++ b/pg-act/ht/keys.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $el_nb = count($_POST['keys']);
 if ($el_nb < 1 OR $el_nb > 8)
diff --git a/pg-act/ns/caa.php b/pg-act/ns/caa.php
index ee528a6..8012efe 100644
--- a/pg-act/ns/caa.php
+++ b/pg-act/ns/caa.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/cname.php b/pg-act/ns/cname.php
index f870b05..b1d4746 100644
--- a/pg-act/ns/cname.php
+++ b/pg-act/ns/cname.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/dname.php b/pg-act/ns/dname.php
index 155fae3..3e0e52e 100644
--- a/pg-act/ns/dname.php
+++ b/pg-act/ns/dname.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/edit.php b/pg-act/ns/edit.php
index 5ee0181..8a27f24 100644
--- a/pg-act/ns/edit.php
+++ b/pg-act/ns/edit.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 nsCheckZonePossession($_POST['zone']);
 
diff --git a/pg-act/ns/ip.php b/pg-act/ns/ip.php
index 4c6b9b9..582ae40 100644
--- a/pg-act/ns/ip.php
+++ b/pg-act/ns/ip.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/loc.php b/pg-act/ns/loc.php
index a3a50de..d49bb44 100644
--- a/pg-act/ns/loc.php
+++ b/pg-act/ns/loc.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/mx.php b/pg-act/ns/mx.php
index c534816..9652573 100644
--- a/pg-act/ns/mx.php
+++ b/pg-act/ns/mx.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/ns.php b/pg-act/ns/ns.php
index c064131..f65a699 100644
--- a/pg-act/ns/ns.php
+++ b/pg-act/ns/ns.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/print.php b/pg-act/ns/print.php
index c415d15..c5f40b3 100644
--- a/pg-act/ns/print.php
+++ b/pg-act/ns/print.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 nsCheckZonePossession($_POST['zone']);
 
diff --git a/pg-act/ns/srv.php b/pg-act/ns/srv.php
index 7c5af6b..e95bebc 100644
--- a/pg-act/ns/srv.php
+++ b/pg-act/ns/srv.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/sshfp.php b/pg-act/ns/sshfp.php
index b3b40a1..9bf4979 100644
--- a/pg-act/ns/sshfp.php
+++ b/pg-act/ns/sshfp.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/sync.php b/pg-act/ns/sync.php
index 9160350..78ba6bd 100644
--- a/pg-act/ns/sync.php
+++ b/pg-act/ns/sync.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $el_nb = count($_POST['syncs']);
 if ($el_nb < 1 OR $el_nb > 8)
diff --git a/pg-act/ns/tlsa.php b/pg-act/ns/tlsa.php
index de5241e..5550e00 100644
--- a/pg-act/ns/tlsa.php
+++ b/pg-act/ns/tlsa.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/txt.php b/pg-act/ns/txt.php
index ebb7ec6..7d5c997 100644
--- a/pg-act/ns/txt.php
+++ b/pg-act/ns/txt.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $values = nsParseCommonRequirements();
 
diff --git a/pg-act/ns/zone-add.php b/pg-act/ns/zone-add.php
index 1af98fa..b77bc04 100644
--- a/pg-act/ns/zone-add.php
+++ b/pg-act/ns/zone-add.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 $_POST['domain'] = formatAbsoluteDomain($_POST['domain']);
 
diff --git a/pg-act/ns/zone-del.php b/pg-act/ns/zone-del.php
index 1a53f91..564eee8 100644
--- a/pg-act/ns/zone-del.php
+++ b/pg-act/ns/zone-del.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 nsCheckZonePossession($_POST['zone']);
 
diff --git a/pg-act/reg/ds.php b/pg-act/reg/ds.php
index bb4168e..65542d9 100644
--- a/pg-act/reg/ds.php
+++ b/pg-act/reg/ds.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (!in_array($_POST['algo'], ['8', '13', '14', '15', '16'], true))
 	output(403, 'Wrong value for <code>algo</code>.');
diff --git a/pg-act/reg/glue.php b/pg-act/reg/glue.php
index a7a8ca9..60177a2 100644
--- a/pg-act/reg/glue.php
+++ b/pg-act/reg/glue.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 regCheckDomainPossession($_POST['domain']);
 
diff --git a/pg-act/reg/ns.php b/pg-act/reg/ns.php
index 487c27e..751f86e 100644
--- a/pg-act/reg/ns.php
+++ b/pg-act/reg/ns.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 regCheckDomainPossession($_POST['domain']);
 
diff --git a/pg-act/reg/print.php b/pg-act/reg/print.php
index b639a52..c98b2a8 100644
--- a/pg-act/reg/print.php
+++ b/pg-act/reg/print.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 regCheckDomainPossession($_POST['domain']);
 
diff --git a/pg-act/reg/register.php b/pg-act/reg/register.php
index ad590f7..a51cdc9 100644
--- a/pg-act/reg/register.php
+++ b/pg-act/reg/register.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (preg_match('/' . SUBDOMAIN_REGEX . '/D', $_POST['subdomain']) !== 1)
 	output(403, _('This format of subdomain is not allowed.'));
diff --git a/pg-act/reg/transfer.php b/pg-act/reg/transfer.php
index f1ffdd9..12b87e7 100644
--- a/pg-act/reg/transfer.php
+++ b/pg-act/reg/transfer.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 if (preg_match('/' . SUBDOMAIN_REGEX . '/D', $_POST['subdomain']) !== 1)
 	output(403, _('This format of subdomain is not allowed.'));
diff --git a/pg-act/reg/unregister.php b/pg-act/reg/unregister.php
index e926a92..0b664ba 100644
--- a/pg-act/reg/unregister.php
+++ b/pg-act/reg/unregister.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 
 regCheckDomainPossession($_POST['domain']);
 
diff --git a/pg-view/auth/approval.php b/pg-view/auth/approval.php
index 43a17d4..2655473 100644
--- a/pg-view/auth/approval.php
+++ b/pg-view/auth/approval.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('This form allows to use an approval key to validate your account. Approval keys are distributed by an administrator upon request.') ?>
 </p>
diff --git a/pg-view/auth/index.php b/pg-view/auth/index.php
index e0d156b..1ef1675 100644
--- a/pg-view/auth/index.php
+++ b/pg-view/auth/index.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <?php displayIndex(); ?>
 
 <h2 id="type"><?= _('Account type') ?></h2>
diff --git a/pg-view/auth/login.php b/pg-view/auth/login.php
index 1adf3be..55a438c 100644
--- a/pg-view/auth/login.php
+++ b/pg-view/auth/login.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p><?= _('New?') ?> <a href="register"><?= _('Create an account') ?></a></p>
 
 <form method="post">
diff --git a/pg-view/auth/logout.php b/pg-view/auth/logout.php
index bf11e4b..1459a06 100644
--- a/pg-view/auth/logout.php
+++ b/pg-view/auth/logout.php
@@ -1,3 +1,3 @@
-<?php
+<?php declare(strict_types=1);
 
 logout();
diff --git a/pg-view/auth/password.php b/pg-view/auth/password.php
index 0836f99..87b9990 100644
--- a/pg-view/auth/password.php
+++ b/pg-view/auth/password.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="current-password"><?= _('Current password') ?></label><br>
 	<input required="" autocomplete="current-password" minlength="8" maxlength="1024" pattern="<?= PASSWORD_REGEX ?>" id="current-password" name="current-password" type="password" placeholder="<?= PLACEHOLDER_PASSWORD ?>"><br>
diff --git a/pg-view/auth/register.php b/pg-view/auth/register.php
index 5ecc0ab..3eda2a0 100644
--- a/pg-view/auth/register.php
+++ b/pg-view/auth/register.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p><?= _('Already have an account?') ?> <a href="login"><?= _('Log in') ?></a></p>
 
 <?= (CONF['common']['services']['auth'] !== 'enabled') ? '<p><strong>' . _('Registrations are currently closed on this installation.') . '</strong></p>' : '' ?>
diff --git a/pg-view/auth/unregister.php b/pg-view/auth/unregister.php
index f517c39..cfdb1ff 100644
--- a/pg-view/auth/unregister.php
+++ b/pg-view/auth/unregister.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('This will delete every resource managed by the current account, including registered domains, hosted DNS records, websites files and cryptographic keys for Onion services and DNSSEC.') ?>
 </p>
diff --git a/pg-view/auth/username.php b/pg-view/auth/username.php
index 1bba92e..95a6397 100644
--- a/pg-view/auth/username.php
+++ b/pg-view/auth/username.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="current-password"><?= _('Current password') ?></label><br>
 	<input required="" autocomplete="current-password" minlength="8" maxlength="1024" pattern="<?= PASSWORD_REGEX ?>" id="current-password" name="current-password" type="password" placeholder="<?= PLACEHOLDER_PASSWORD ?>"><br>
diff --git a/pg-view/ht/add-dns.php b/pg-view/ht/add-dns.php
index 96d665e..02432cf 100644
--- a/pg-view/ht/add-dns.php
+++ b/pg-view/ht/add-dns.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('A Let\'s Encrypt certificate will be obtained.') ?>
 </p>
diff --git a/pg-view/ht/add-onion.php b/pg-view/ht/add-onion.php
index 40f6bed..aa04ecd 100644
--- a/pg-view/ht/add-onion.php
+++ b/pg-view/ht/add-onion.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="dir"><?= _('Target directory') ?></label><br>
 	<select required="" name="dir" id="dir">
diff --git a/pg-view/ht/add-subdomain.php b/pg-view/ht/add-subdomain.php
index 3fce989..319e4b6 100644
--- a/pg-view/ht/add-subdomain.php
+++ b/pg-view/ht/add-subdomain.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('The subdomain can only contain %1$s, %2$s and %3$s, and must be between 4 and 63 characters. It can\'t have an hyphen (%3$s) in first, last or both third and fourth position.'), '<abbr title="abcdefghijklmnopqrstuvwxyz"><code>a</code>-<code>z</code></abbr>',  '<abbr title="0123456789"><code>0</code>-<code>9</code></abbr>', '<code>-</code>') ?>
 </p>
diff --git a/pg-view/ht/add-subpath.php b/pg-view/ht/add-subpath.php
index 948abc4..4a0ab05 100644
--- a/pg-view/ht/add-subpath.php
+++ b/pg-view/ht/add-subpath.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('The path can only contain %1$s, %2$s and %3$s, and must be between 4 and 63 characters.'), '<abbr title="abcdefghijklmnopqrstuvwxyz"><code>a</code>-<code>z</code></abbr>',  '<abbr title="0123456789"><code>0</code>-<code>9</code></abbr>', '<code>-</code>') ?>
 </p>
diff --git a/pg-view/ht/del.php b/pg-view/ht/del.php
index d74adb8..e3bc4bd 100644
--- a/pg-view/ht/del.php
+++ b/pg-view/ht/del.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="site"><?= _('Access to delete') ?></label><br>
 	<select required="" name="site" id="site">
diff --git a/pg-view/ht/index.php b/pg-view/ht/index.php
index 388877d..e55b292 100644
--- a/pg-view/ht/index.php
+++ b/pg-view/ht/index.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('This service allows you to send files on the server using SFTP, and to make them publicly available with HTTP.') ?>
 </p>
diff --git a/pg-view/ht/keys.php b/pg-view/ht/keys.php
index 3f613ef..4529576 100755
--- a/pg-view/ht/keys.php
+++ b/pg-view/ht/keys.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('In addition to your password, you can also access your SFTP space using Ed25519 SSH keys. A key can be granted modification rights to the full space (<code>/</code>) or to any arbitrary subdirectory. A key is always  allowed to list any directory content.') ?>
 </p>
diff --git a/pg-view/index.php b/pg-view/index.php
index 355c09c..ba564cb 100644
--- a/pg-view/index.php
+++ b/pg-view/index.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <nav>
 	<p>
 		<span aria-hidden="true">➡️ </span><em><a href="<?= CONF['common']['about_url'] ?>"><?= _('About this installation') ?></a></em>
diff --git a/pg-view/ns/caa.php b/pg-view/ns/caa.php
index 2040b1b..464c207 100644
--- a/pg-view/ns/caa.php
+++ b/pg-view/ns/caa.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="flag"><?= _('Flag') ?></label>
diff --git a/pg-view/ns/cname.php b/pg-view/ns/cname.php
index 8c97807..201b54f 100644
--- a/pg-view/ns/cname.php
+++ b/pg-view/ns/cname.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="cname"><?= _('Canonical name') ?></label>
diff --git a/pg-view/ns/dname.php b/pg-view/ns/dname.php
index 40a748a..0ca5bbe 100644
--- a/pg-view/ns/dname.php
+++ b/pg-view/ns/dname.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="dname"><?= _('Delegation name') ?></label>
diff --git a/pg-view/ns/edit.php b/pg-view/ns/edit.php
index bb14b63..52e399d 100644
--- a/pg-view/ns/edit.php
+++ b/pg-view/ns/edit.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="zone"><?= _('Zone to be changed') ?></label>
 	<br>
diff --git a/pg-view/ns/form.ns.php b/pg-view/ns/form.ns.php
index 3c05c42..6cc6d25 100644
--- a/pg-view/ns/form.ns.php
+++ b/pg-view/ns/form.ns.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 	<label for="action"><?= _('Action') ?></label>
 	<select name="action" id="action">
 		<option value="add"<?= ($_POST['action'] ?? NULL) === 'add' ? ' selected=""' : '' ?>><?= _('Add') ?></option>
diff --git a/pg-view/ns/index.php b/pg-view/ns/index.php
index 72e0603..37f94b7 100644
--- a/pg-view/ns/index.php
+++ b/pg-view/ns/index.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('This service allows to host and manage DNS records inside a DNS zone.') ?>
 </p>
diff --git a/pg-view/ns/ip.php b/pg-view/ns/ip.php
index 51d8392..1eefebf 100644
--- a/pg-view/ns/ip.php
+++ b/pg-view/ns/ip.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="ip"><?= _('IP address') ?></label><br>
diff --git a/pg-view/ns/loc.php b/pg-view/ns/loc.php
index 5344a94..3273c1e 100644
--- a/pg-view/ns/loc.php
+++ b/pg-view/ns/loc.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<fieldset>
diff --git a/pg-view/ns/mx.php b/pg-view/ns/mx.php
index dc8c933..0e04b64 100644
--- a/pg-view/ns/mx.php
+++ b/pg-view/ns/mx.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="priority"><?= _('Priority') ?></label>
diff --git a/pg-view/ns/ns.php b/pg-view/ns/ns.php
index 0cd6fef..a201f92 100644
--- a/pg-view/ns/ns.php
+++ b/pg-view/ns/ns.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="ns"><?= _('Name server') ?></label>
diff --git a/pg-view/ns/print.php b/pg-view/ns/print.php
index 3492b1d..d3236cd 100644
--- a/pg-view/ns/print.php
+++ b/pg-view/ns/print.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<input type="radio" name="print" id="table" value="table" checked="">
 	<label for="table"><?= _('Records table') ?></label>
diff --git a/pg-view/ns/srv.php b/pg-view/ns/srv.php
index 4972852..3445eaa 100644
--- a/pg-view/ns/srv.php
+++ b/pg-view/ns/srv.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 
diff --git a/pg-view/ns/sshfp.php b/pg-view/ns/sshfp.php
index 4f72ea7..261598d 100644
--- a/pg-view/ns/sshfp.php
+++ b/pg-view/ns/sshfp.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 
diff --git a/pg-view/ns/sync.php b/pg-view/ns/sync.php
index 2e52645..fade7f9 100644
--- a/pg-view/ns/sync.php
+++ b/pg-view/ns/sync.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('AAAA, A and CAA records are regularly copied from the source domain to the target domain. Their TTLs are set to %s seconds.'), SYNC_TTL) ?>
 </p>
diff --git a/pg-view/ns/tlsa.php b/pg-view/ns/tlsa.php
index 3e0a812..97fe70e 100644
--- a/pg-view/ns/tlsa.php
+++ b/pg-view/ns/tlsa.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 
diff --git a/pg-view/ns/txt.php b/pg-view/ns/txt.php
index 5cd0f7b..a39c4fc 100644
--- a/pg-view/ns/txt.php
+++ b/pg-view/ns/txt.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/ns/form.ns.php'; ?>
 	<label for="txt"><?= _('Text') ?></label>
diff --git a/pg-view/ns/zone-add.php b/pg-view/ns/zone-add.php
index 39522cf..a9f0932 100644
--- a/pg-view/ns/zone-add.php
+++ b/pg-view/ns/zone-add.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('To prove that you own this domain, it must have a NS record equal to %s when the form is being processed.'), '<code>' . getAuthToken() . '._domain-verification.' . SERVER_NAME . '.</code>') ?>
 </p>
diff --git a/pg-view/ns/zone-del.php b/pg-view/ns/zone-del.php
index fb0b580..956939e 100644
--- a/pg-view/ns/zone-del.php
+++ b/pg-view/ns/zone-del.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 	<label for="zone"><?= _('Zone') ?></label>
 	<select required="" name="zone" id="zone">
diff --git a/pg-view/reg/ds.php b/pg-view/reg/ds.php
index 7338136..7aab92a 100644
--- a/pg-view/reg/ds.php
+++ b/pg-view/reg/ds.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/reg/select-action.inc.php'; ?>
 	<br>
diff --git a/pg-view/reg/glue.php b/pg-view/reg/glue.php
index 44ca00a..fae84b2 100644
--- a/pg-view/reg/glue.php
+++ b/pg-view/reg/glue.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/reg/select-action.inc.php'; ?>
 	<fieldset>
diff --git a/pg-view/reg/index.php b/pg-view/reg/index.php
index a00b7db..aafa686 100644
--- a/pg-view/reg/index.php
+++ b/pg-view/reg/index.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('This domain name registry allows to register domains ending with <code>%1$s</code>, for instance <code><em>domain</em>%1$s</code>.'), '.' . key(CONF['reg']['suffixes'])) ?>
 </p>
diff --git a/pg-view/reg/ns.php b/pg-view/reg/ns.php
index b092e63..e4ba2e5 100644
--- a/pg-view/reg/ns.php
+++ b/pg-view/reg/ns.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/reg/select-action.inc.php'; ?>
 	<br>
diff --git a/pg-view/reg/print.php b/pg-view/reg/print.php
index f59c6f4..56d09c6 100644
--- a/pg-view/reg/print.php
+++ b/pg-view/reg/print.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <form method="post">
 <?php require ROOT_PATH . '/pg-view/reg/select-domain.inc.php'; ?>
 	<br>
diff --git a/pg-view/reg/register.php b/pg-view/reg/register.php
index 522257e..2e2fd53 100644
--- a/pg-view/reg/register.php
+++ b/pg-view/reg/register.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('Register a new domain on your account.') ?>
 </p>
diff --git a/pg-view/reg/select-action.inc.php b/pg-view/reg/select-action.inc.php
index cfc5d3c..75d79ff 100644
--- a/pg-view/reg/select-action.inc.php
+++ b/pg-view/reg/select-action.inc.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 	<label for="action"><?= _('Action') ?></label>
 	<select name="action" id="action">
 		<option value="add"<?= ($_POST['action'] ?? NULL) === 'add' ? ' selected=""' : '' ?>><?= _('Add') ?></option>
diff --git a/pg-view/reg/select-domain.inc.php b/pg-view/reg/select-domain.inc.php
index 0902483..2303bd6 100644
--- a/pg-view/reg/select-domain.inc.php
+++ b/pg-view/reg/select-domain.inc.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 	<label for="domain"><?= _('Domain') ?></label>
 	<br>
 	<select required="" name="domain" id="domain">
diff --git a/pg-view/reg/transfer.php b/pg-view/reg/transfer.php
index bdddda7..c76f28c 100644
--- a/pg-view/reg/transfer.php
+++ b/pg-view/reg/transfer.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= sprintf(_('To prove that you are allowed to receive the domain by its current owner, the domain must have an NS record equal to %s when the form is being processed. The NS record will be automatically deleted once validated.'), '<code>' . getAuthToken() . '._transfer-verification.' . SERVER_NAME . '.</code>') ?>
 </p>
diff --git a/pg-view/reg/unregister.php b/pg-view/reg/unregister.php
index 0ab31f6..e192147 100644
--- a/pg-view/reg/unregister.php
+++ b/pg-view/reg/unregister.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <p>
 	<?= _('This will unregister the domain, making it registerable by anyone again (after a delay of 1 year plus half the registration period, with a maximum of 8 years).') ?>
 </p>
diff --git a/router.php b/router.php
index 0c0a024..6a2635a 100644
--- a/router.php
+++ b/router.php
@@ -1,4 +1,4 @@
-<?php
+<?php declare(strict_types=1);
 require 'init.php';
 
 $pageAddress = substr($_SERVER['REQUEST_URI'], strlen(CONF['common']['prefix']) + 1);
diff --git a/sftpgo-auth.php b/sftpgo-auth.php
index 6ec3ef8..b73dbbb 100644
--- a/sftpgo-auth.php
+++ b/sftpgo-auth.php
@@ -1,4 +1,5 @@
-<?php // ServNest authenticator for SFTPGo https://github.com/drakkan/sftpgo/blob/main/docs/external-auth.md
+<?php declare(strict_types=1);
+// ServNest authenticator for SFTPGo https://github.com/drakkan/sftpgo/blob/main/docs/external-auth.md
 
 const DEBUG = false;
 !DEBUG or ob_start();
diff --git a/view.php b/view.php
index 67e9cc7..9bf6544 100644
--- a/view.php
+++ b/view.php
@@ -1,3 +1,4 @@
+<?php declare(strict_types=1); ?>
 <!DOCTYPE html>
 <html lang="<?= LOCALE ?>"<?= empty(SERVICE) ? '' : ' class="' . SERVICE . '"' ?>>
 	<head>