Quantumult X

Look inside your own traffic: Quantumult X is a network utility for people who debug web requests or tune their proxies, and you can download the Quantumult X IPA for iPhone straight from builds.io.

What is Quantumult X?

The App Store lists it under Utilities with Developer Tools as the second genre, and the developer is Cross Utility Ltd. It is a ground-up rebuild of the earlier Quantumult, not a patch of the old code. The audience splits in two: web developers who want visibility into HTTP activity, and users who need control over where their connections go.

For developers, the app can record complete HTTP requests and responses, bodies included, once the HTTP debug option is turned on. MitM decryption covers traffic that arrives through the TUN interface when MitM is enabled. The rewrite engine can answer with a 302 or 307 redirect, or edit request and response headers and bodies on the fly. Per-domain DNS settings, for IPv4 or IPv6, are handled through the configuration profile rather than through menus.

For proxy users, the app speaks the Shadowsocks protocol, including the obfs-tls and obfs-http plugins, and Shadowsocks running over WebSocket and TLS when the server side is deployed with v2ray-core. UDP relay works if the server allows it. Request routing is driven by filters that match a full host, a host suffix or a keyword, so different traffic can follow different policies.

Quantumult X key features

• HTTP activity capture with full request and response bodies
• MitM decryption for traffic coming through the TUN interface
• Rewrite rules for redirects and header or body edits
• Custom DNS for chosen domains
• Shadowsocks with obfs plugins, WebSocket and TLS transports
• UDP relay where the server supports it
• Policy filters by host, suffix or keyword

Price and requirements

This is a paid app in the App Store, listed at 9.99 USD, and the listing here is the regular release of the app. It first appeared in October 2019, needs iOS 15.0 or later and has a 4+ rating. The latest release notes mention optimisation for iPhone Duo. Debug, MitM and rewrite functions each have to be enabled by the user, and the DNS overrides are configured in the profile file.

To get started, open the Quantumult X page on builds.io and send it to your iPhone with one tap, no PC.