A native proxy capture & API debugging toolkit for Apple platforms.

Inspect every request. Replay anything. Built end-to-end in Swift.

Trace is a network traffic inspector and API workbench for iOS and macOS. It combines a full HTTP/HTTPS/HTTP2 capturing proxy, TLS interception, WebSocket and SSE inspection, and a first-class request composer — all in native SwiftUI apps with no Flutter, CocoaPods, or web wrappers in the build graph.

Think of it as a debugging proxy and an API client living in the same app, sharing the same capture pipeline.

🔍 Capture & Proxy

• HTTP/1.1, HTTP/2, and HTTPS CONNECT capture built on SwiftNIO
• On-device TLS interception with a locally generated CA and per-host leaf certificates
• TUN-based packet capture for transport-level visibility on iOS
• WebSocket (incl. RFC 8441 over HTTP/2) and Server-Sent Events inspection
• gzip/deflate decoding, HAR & cURL import/export, search, favorites, history

🧪 Compose — the API Workbench

• Author, send, save, and organize requests into collections, folders, and environments
• Turn any captured request into an editable, replayable request
• Rich auth: API key, Basic, Bearer, JWT, OAuth 2.0 (PKCE/device/refresh), Digest, AWS SigV4, HMAC
• JavaScript pre-request / post-response scripting with a pm.* compatibility shim
• Flow & batch runners, assertions, timing waterfalls, diffs, and Markdown run reports
• Imports cURL, HAR, Postman, Insomnia, OpenAPI/Swagger; exports cURL, Postman, OpenAPI, Markdown

🛠 Rules & Routing

• Host mapping, rewrites, breakpoints, blocking, and scripted interceptors
• Direct, HTTP upstream, and SOCKS5 proxy routing
• Importable/exportable rule bundles

Swift 6 · SwiftUI · SwiftNIO · NIOSSL · NIOHTTP2 · NetworkExtension · JavaScriptCore · Swift Certificates

The codebase is organized as native app targets plus local Swift packages for capture, platform services, packet inspection, and a shared design system.

Trace is in active development across iOS and macOS. Capture, TLS interception, the Compose workbench, WebSocket/SSE inspection, and rule engine are implemented and evolving.

_{Made with Swift for people who live in the network tab.}