diff --git a/api/v1/enforce_api_rbac.php b/api/v1/enforce_api_rbac.php
index 08811f0b..c36ac9e3 100644
--- a/api/v1/enforce_api_rbac.php
+++ b/api/v1/enforce_api_rbac.php
@@ -124,6 +124,7 @@ $resource_module = [
     'networks'      => 'module_support',
     'software'      => 'module_support',
     'tickets'       => 'module_support',
+    'ticket_replies' => 'module_support',
     'technicians'   => 'module_support',
     'clients'       => 'module_client',
     'contacts'      => 'module_client',
diff --git a/api/v1/ticket_replies/create.php b/api/v1/ticket_replies/create.php
new file mode 100644
index 00000000..e40c3358
--- /dev/null
+++ b/api/v1/ticket_replies/create.php
@@ -0,0 +1,187 @@
+<?php
+/*
+ * API - Ticket Replies - Create
+ * POST /api/v1/ticket_replies/create.php
+ *
+ * Adds a reply to an existing ticket. This is the endpoint an RMM, monitoring
+ * system or chat bridge uses to append to a ticket it didn't open.
+ *
+ * Parameters (POST, JSON body):
+ *   api_key                  required - Your API key
+ *   client_id                required - Must match the ticket's client (restricted
+ *                                       keys only; unrestricted/admin keys may omit)
+ *   ticket_id                required - Ticket to reply to
+ *   ticket_reply             required - Reply body (HTML allowed, same as the UI)
+ *   ticket_reply_type        optional - 'Internal' (default) or 'Public'.
+ *                                       Public emails the contact and any watchers
+ *                                       and counts as the ticket's first response.
+ *   ticket_reply_time_worked optional - HH:MM:SS, default 00:00:00
+ *   ticket_status            optional - Also set the ticket status. Status 4 resolves
+ *                                       the ticket (sets resolved_at + SLA met).
+ *
+ * Security:
+ *   - The parent ticket is loaded through apiClientScopeSql(), so a restricted key
+ *     can't reply to another client's ticket even with a valid ticket_id.
+ *   - The client_id supplied for the write must match the ticket's own client.
+ *   - The reply is attributed to the user the API key runs as ($session_user_id,
+ *     set by enforce_api_rbac.php), so ticket history stays honest.
+ *
+ * Note: 'ticket_replies' must be present in $resource_module in enforce_api_rbac.php
+ * (mapped to module_support) or the enforcer will fail closed on this endpoint.
+ */
+
+require_once '../validate_api_key.php';
+
+require_once '../require_post_method.php';
+
+// Ticket/mail settings for public reply notifications
+require_once "../../../includes/load_global_settings.php";
+
+// Parse Info
+$ticket_id = intval($_POST['ticket_id'] ?? 0);
+$ticket_reply_row = false; // Creation, not an update
+require_once 'ticket_reply_model.php';
+
+// Default
+$insert_id = false;
+
+if (!empty($ticket_id) && !empty($reply)) {
+
+    // Load the parent ticket, scoped to the key user's client access
+    $ticket_sql = mysqli_query(
+        $mysqli,
+        "SELECT * FROM tickets
+         WHERE ticket_id = $ticket_id
+           AND 1=1 " . apiClientScopeSql('ticket_client_id') . "
+         LIMIT 1"
+    );
+    $ticket_row = $ticket_sql ? mysqli_fetch_assoc($ticket_sql) : null;
+
+    // The client named on the write must be the ticket's own client
+    if ($ticket_row && $client_id != 0 && intval($ticket_row['ticket_client_id']) !== $client_id) {
+        $ticket_row = null;
+    }
+
+    if ($ticket_row) {
+
+        $ticket_prefix = escapeSql($ticket_row['ticket_prefix']);
+        $ticket_number = intval($ticket_row['ticket_number']);
+        $ticket_subject = escapeSql($ticket_row['ticket_subject']);
+        $ticket_url_key = escapeSql($ticket_row['ticket_url_key']);
+        $ticket_first_response_at = escapeSql($ticket_row['ticket_first_response_at']);
+        $client_id = intval($ticket_row['ticket_client_id']);
+
+        // Mark first response time if required - internal notes don't count as a response
+        if (empty($ticket_first_response_at) && $reply_type == 'Public') {
+            setTicketFirstResponse($ticket_id);
+        }
+
+        // Add reply
+        $insert_sql = mysqli_query($mysqli, "INSERT INTO ticket_replies SET ticket_reply = '$reply', ticket_reply_type = '$reply_type', ticket_reply_time_worked = '$reply_time_worked', ticket_reply_by = $session_user_id, ticket_reply_ticket_id = $ticket_id");
+
+        // Check insert & get insert ID
+        if ($insert_sql) {
+            $insert_id = mysqli_insert_id($mysqli);
+
+            // Optional status change alongside the reply
+            if (!empty($reply_ticket_status)) {
+                mysqli_query($mysqli, "UPDATE tickets SET ticket_status = $reply_ticket_status WHERE ticket_id = $ticket_id LIMIT 1");
+
+                // Resolve the ticket, if set
+                if ($reply_ticket_status == 4) {
+                    mysqli_query($mysqli, "UPDATE tickets SET ticket_resolved_at = NOW() WHERE ticket_id = $ticket_id AND ticket_resolved_at IS NULL LIMIT 1");
+                    setTicketResolutionSlaMet($ticket_id);
+
+                    logAudit("Ticket", "Resolved", "Resolved ticket $ticket_prefix$ticket_number via API ($api_key_name)", $client_id, $ticket_id);
+
+                    triggerCustomAction('ticket_resolve', $ticket_id);
+                }
+            }
+
+            // Logging
+            logAudit("Ticket", "Reply", "Added a $reply_type reply to ticket $ticket_prefix$ticket_number - $ticket_subject via API ($api_key_name)", $client_id, $ticket_id);
+            logAudit("API", "Success", "Added a $reply_type reply to ticket $ticket_prefix$ticket_number via API ($api_key_name)", $client_id);
+
+            // Custom action/notif handler
+            if ($reply_type == 'Internal') {
+                triggerCustomAction('ticket_reply_agent_internal', $ticket_id);
+            } else {
+                triggerCustomAction('reply_reply_agent_public', $ticket_id);
+            }
+
+            // Email the contact & watchers on a public reply (mirrors the agent reply handler)
+            if ($reply_type == 'Public' && !empty($config_smtp_provider)) {
+
+                $notify_sql = mysqli_query(
+                    $mysqli,
+                    "SELECT contact_name, contact_email, ticket_status_name
+                     FROM tickets
+                     LEFT JOIN contacts ON ticket_contact_id = contact_id
+                     LEFT JOIN ticket_statuses ON ticket_status = ticket_status_id
+                     WHERE ticket_id = $ticket_id"
+                );
+                $notify_row = mysqli_fetch_assoc($notify_sql);
+
+                $contact_name = escapeSql($notify_row['contact_name']);
+                $contact_email = escapeSql($notify_row['contact_email']);
+                $ticket_status_name = escapeSql($notify_row['ticket_status_name']);
+
+                // Sanitize config vars from load_global_settings.php
+                $from_name = escapeSql($config_ticket_from_name);
+                $from_email = escapeSql($config_ticket_from_email);
+
+                $company_sql = mysqli_query($mysqli, "SELECT company_name, company_phone, company_phone_country_code FROM companies WHERE company_id = 1");
+                $company_row = mysqli_fetch_assoc($company_sql);
+                $company_name = escapeSql($company_row['company_name']);
+                $company_phone = escapeSql(formatPhoneNumber($company_row['company_phone'], $company_row['company_phone_country_code']));
+
+                $subject = "Ticket update - [$ticket_prefix$ticket_number] - $ticket_subject";
+                $body = "<i style=\'color: #808080\'>##- Please type your reply above this line -##</i><br><br>Hello $contact_name,<br><br>Your ticket regarding $ticket_subject has been updated.<br><br>--------------------------------<br>$reply<br>--------------------------------<br><br>Ticket: $ticket_prefix$ticket_number<br>Subject: $ticket_subject<br>Status: $ticket_status_name<br>Portal: <a href=\'https://$config_base_url/guest/guest_view_ticket.php?ticket_id=$ticket_id&url_key=$ticket_url_key\'>View ticket</a><br><br>--<br>$company_name - Support<br>$from_email<br>$company_phone";
+
+                $data = [];
+
+                // Email ticket contact
+                if (filter_var($contact_email, FILTER_VALIDATE_EMAIL)) {
+                    $data[] = [
+                        'from' => $from_email,
+                        'from_name' => $from_name,
+                        'recipient' => $contact_email,
+                        'recipient_name' => $contact_name,
+                        'subject' => $subject,
+                        'body' => $body
+                    ];
+                }
+
+                // Also email all the watchers
+                $watcher_body = $body . "<br><br>----------------------------------------<br>YOU ARE A COLLABORATOR ON THIS TICKET";
+                $sql_watchers = mysqli_query($mysqli, "SELECT watcher_name, watcher_email FROM ticket_watchers WHERE watcher_ticket_id = $ticket_id");
+                while ($watcher_row = mysqli_fetch_assoc($sql_watchers)) {
+                    $watcher_name = escapeSql($watcher_row['watcher_name']);
+                    $watcher_email = escapeSql($watcher_row['watcher_email']);
+
+                    if (filter_var($watcher_email, FILTER_VALIDATE_EMAIL)) {
+                        $data[] = [
+                            'from' => $from_email,
+                            'from_name' => $from_name,
+                            'recipient' => $watcher_email,
+                            'recipient_name' => $watcher_name,
+                            'subject' => $subject,
+                            'body' => $watcher_body
+                        ];
+                    }
+                }
+
+                if (!empty($data)) {
+                    addToMailQueue($data);
+                }
+
+            }
+
+        }
+
+    }
+
+}
+
+// Output
+require_once '../create_output.php';
diff --git a/api/v1/ticket_replies/read.php b/api/v1/ticket_replies/read.php
new file mode 100644
index 00000000..1819d997
--- /dev/null
+++ b/api/v1/ticket_replies/read.php
@@ -0,0 +1,96 @@
+<?php
+/*
+ * API - Ticket Replies - Read
+ * GET /api/v1/ticket_replies/read.php
+ *
+ * Returns replies belonging to tickets within the key user's client access.
+ *
+ * Parameters (GET):
+ *   api_key           required - Your API key
+ *   ticket_reply_id   optional - Return a single reply by its own ID
+ *   ticket_id         optional - Return all replies on a single ticket
+ *   type              optional - Filter by reply type: Internal, Public or Client
+ *   include_archived  optional - Set to 1 to include archived replies (default: excluded)
+ *   limit             optional - Max rows to return (default 50)
+ *   offset            optional - Offset for pagination (default 0)
+ *
+ * Security:
+ *   - ticket_replies are always INNER JOINed to tickets so that ticket_client_id is
+ *     checked against the key user's client scope. A restricted key can never read
+ *     replies on another client's ticket, even when ticket_reply_id is supplied
+ *     directly.
+ *
+ * Notes:
+ *   - ticket_reply_by is a user_id on Internal/Public replies and a contact_id on
+ *     Client replies (those come from the email parser). ticket_reply_by_name is
+ *     resolved here so callers don't have to know that.
+ *   - Archived replies are hidden everywhere in the UI, so they're excluded by
+ *     default here too.
+ *   - Unlike invoice_items/read.php this does not require a filter - an unfiltered
+ *     call lists all replies the key can see, matching tickets/read.php.
+ */
+
+require_once '../validate_api_key.php';
+
+require_once '../require_get_method.php';
+
+// Archived replies are hidden throughout the UI - match that unless asked otherwise
+$archived_sql = '';
+if (empty($_GET['include_archived'])) {
+    $archived_sql = " AND tr.ticket_reply_archived_at IS NULL";
+}
+
+// Optional reply type filter (whitelisted, so it's safe to interpolate)
+$type_sql = '';
+if (isset($_GET['type'])) {
+    $type = ucfirst(strtolower($_GET['type']));
+    if (in_array($type, ['Internal', 'Public', 'Client'], true)) {
+        $type_sql = " AND tr.ticket_reply_type = '$type'";
+    }
+}
+
+$select_sql =
+    "SELECT tr.*,
+            t.ticket_prefix, t.ticket_number, t.ticket_subject, t.ticket_client_id,
+            COALESCE(u.user_name, c.contact_name) AS ticket_reply_by_name
+     FROM ticket_replies tr
+     INNER JOIN tickets t ON t.ticket_id = tr.ticket_reply_ticket_id
+     LEFT JOIN users u ON tr.ticket_reply_type != 'Client' AND u.user_id = tr.ticket_reply_by
+     LEFT JOIN contacts c ON tr.ticket_reply_type = 'Client' AND c.contact_id = tr.ticket_reply_by";
+
+// Specific reply via ID (single)
+if (isset($_GET['ticket_reply_id'])) {
+    $id = intval($_GET['ticket_reply_id']);
+    $sql = mysqli_query(
+        $mysqli,
+        "$select_sql
+         WHERE tr.ticket_reply_id = '$id'
+           AND 1=1 " . apiClientScopeSql('t.ticket_client_id') . "$archived_sql$type_sql
+         LIMIT 1"
+    );
+
+} elseif (isset($_GET['ticket_id'])) {
+    // All replies on a specific ticket
+    $ticket_id = intval($_GET['ticket_id']);
+    $sql = mysqli_query(
+        $mysqli,
+        "$select_sql
+         WHERE tr.ticket_reply_ticket_id = '$ticket_id'
+           AND 1=1 " . apiClientScopeSql('t.ticket_client_id') . "$archived_sql$type_sql
+         ORDER BY tr.ticket_reply_id ASC
+         LIMIT $limit OFFSET $offset"
+    );
+
+} else {
+    // All replies the key can see
+    $sql = mysqli_query(
+        $mysqli,
+        "$select_sql
+         WHERE 1=1 " . apiClientScopeSql('t.ticket_client_id') . "$archived_sql$type_sql
+         ORDER BY tr.ticket_reply_id ASC
+         LIMIT $limit OFFSET $offset"
+    );
+}
+
+// Output
+require_once "../read_output.php";
diff --git a/api/v1/ticket_replies/ticket_reply_model.php b/api/v1/ticket_replies/ticket_reply_model.php
new file mode 100644
index 00000000..6fecf396
--- /dev/null
+++ b/api/v1/ticket_replies/ticket_reply_model.php
@@ -0,0 +1,45 @@
+<?php
+
+// Variable assignment from POST (or: blank/from DB if updating)
+
+if (isset($_POST['ticket_reply'])) {
+    $reply = mysqli_real_escape_string($mysqli, $_POST['ticket_reply']);
+} elseif ($ticket_reply_row) {
+    $reply = mysqli_real_escape_string($mysqli, $ticket_reply_row['ticket_reply']);
+} else {
+    $reply = '';
+}
+
+// Reply type - defaults to Internal so an integration can't accidentally email a
+// client. 'Client' is reserved for inbound contact replies (the email parser) and
+// is not accepted here.
+if (isset($_POST['ticket_reply_type'])) {
+    $reply_type = ucfirst(strtolower($_POST['ticket_reply_type']));
+    if (!in_array($reply_type, ['Internal', 'Public'], true)) {
+        $reply_type = 'Internal';
+    }
+} elseif ($ticket_reply_row) {
+    $reply_type = escapeSql($ticket_reply_row['ticket_reply_type']);
+} else {
+    $reply_type = 'Internal';
+}
+
+// Time worked - HH:MM:SS. Defaults to none: the API isn't a technician at a keyboard,
+// so time only gets logged when the caller explicitly says so.
+if (isset($_POST['ticket_reply_time_worked'])) {
+    $reply_time_worked = escapeSql($_POST['ticket_reply_time_worked']);
+    if (!preg_match('/^\d{1,3}:[0-5]\d:[0-5]\d$/', $reply_time_worked)) {
+        $reply_time_worked = '00:00:00';
+    }
+} elseif ($ticket_reply_row) {
+    $reply_time_worked = escapeSql($ticket_reply_row['ticket_reply_time_worked']);
+} else {
+    $reply_time_worked = '00:00:00';
+}
+
+// Optional status change alongside the reply (0 = leave the ticket status as-is)
+if (isset($_POST['ticket_status'])) {
+    $reply_ticket_status = intval($_POST['ticket_status']);
+} else {
+    $reply_ticket_status = 0;
+}