Port Scanner

Scan ports of a specified host or IP address locally in the browser. Supports common presets and custom ranges.

Browser Sandbox Security & Scanner Notice

1. 浏览器禁用端口（Unsafe Ports）：现代浏览器出于安全考虑，默认拦截了对某些端口的请求（如 21-FTP、22-SSH、23-Telnet、25-SMTP 等）。这些端口会被标记为“浏览器拦截”，无法从网页端建立连接。如需扫描，请使用本地命令 nmap -p [端口] [目标]。

2. 协议兼容性限制：由于浏览器只能发送 HTTP 族协议请求，对于不响应 HTTP 的非 Web 端口（如 MySQL 3306、Redis 6379），即使端口开放，连接后也会因为协议不匹配返回 fetch 失败（TypeError）。本工具会通过耗时差异进行智能推断，若失败发生在极短时间内（通常 < 15ms），倾向于“关闭”；若有明显延时或异常错误，通常倾向于服务存在但未响应 HTTP。

3. 混合内容安全（Mixed Content）：当本网站以 HTTPS 协议运行时，浏览器默认禁止对非安全 HTTP 的外部 IP 发送请求。但对本机 127.0.0.1 / localhost 拥有豁免权。因此，本工具最适合用于本地开发环境调试。若要扫描公网主机的 HTTP 端口，可能受到混合内容策略限制。

Target Host / IP

Timeout Limit (ms)

Concurrency Workers

Custom Ports Range

Preset Port Groups

Total Scanned: 15

Developer Tool Guide

About Port Scanner

Niuma Tools Dedicated to improving the daily efficiency of professionals and frontend developers. This is a ready-to-use, secure, and highly efficient productivity tool. Secure online IP port scanner. Supports custom port ranges and preset service port descriptions. Features multithreaded scanning, RTT timing analysis, and report export.

Usage Notice & Privacy Guarantee

We have always adhered to the core development philosophy of "Offline First, Security First". Many features on this page are implemented through the local computing APIs of modern browsers, effectively solving the unpredictable privacy leakage risks faced when sending files and data to other websites. You can save it to your bookmarks as a solid and reliable part of your daily development, testing, or content creation workflow.

Related keywords: port scanner / online port checker / IP scan / check port open / LAN scan / common ports