See every HTTP request your app makes. Rewrite responses, simulate slow networks, and automate it all with a REST API — the workflow Charles Proxy and Fiddler should have had years ago.
One binary. Double-click to launch. No installer, no Java runtime, no Docker required. The proxy starts automatically on port 8888.
Set localhost:8888 as your HTTP proxy. Works with browsers, mobile apps, React, Node, Python — anything that speaks HTTP.
Every request appears instantly in the desktop app. Then automate — create rewrite rules, throttle profiles, and filters via the REST API. No clicking required.
Full MITM proxy with auto-generated certificates. Inspect encrypted traffic between any client and any server, including mobile apps.
Map Remote, Map Local, header inject/modify/remove, body find & replace, URL rewriting, status code overrides. All via API or GUI.
16 built-in presets from 56K modem to 5G fiber. Custom latency, bandwidth caps, and packet loss simulation. Test edge cases instantly.
Search across URLs, headers, request/response bodies. Filter by method, status code range, or hostname. Find the needle in your haystack.
Re-send any captured request with one click, or compose custom requests from scratch. Like Postman built into your proxy.
Save, load, import, and export capture sessions. Share compressed .pcsession files with teammates or attach them to bug reports.
Export to standard HTTP Archive format. Import into Chrome DevTools, Lighthouse, or any HAR-compatible tool for further analysis.
Get notified via Slack in real-time when specific patterns appear. Monitor for 5xx errors, slow responses, or custom conditions. Email notifications coming soon.
Every feature exposed via a clean REST API with OpenAPI docs. Script your proxy config in CI/CD, tests, or any language you use.
| Feature | ProxyCat | Charles Proxy | Fiddler | mitmproxy | Proxyman |
|---|---|---|---|---|---|
| SSL/HTTPS Interception | ✓ | ✓ | ✓ | ✓ | ✓ |
| REST API for All Features | ✓ | ✗ | ✗ | Scripting | ✗ |
| Map Remote / Map Local | ✓ | ✓ | ✓ | Manual | ✓ |
| Header & Body Rewriting | ✓ | ✓ | ✓ | ✓ | ✓ |
| Network Throttling (16 presets) | ✓ | 3 presets | Basic | ✗ | Basic |
| Packet Loss Simulation | ✓ | ✗ | ✗ | ✗ | ✗ |
| Full-Text Search | ✓ | Basic | ✓ | CLI filter | ✓ |
| Request Replay & Compose | ✓ | Repeat only | ✓ | CLI replay | ✓ |
| Session Save / Export / Import | ✓ | ✓ | ✓ | HAR only | ✓ |
| HAR Export | ✓ | ✓ | ✓ | ✓ | ✓ |
| Interactive API Docs (Scalar) | ✓ | ✗ | ✗ | ✗ | ✗ |
| Slack Notifications | ✓ | ✗ | ✗ | ✗ | ✗ |
| Docker / Headless Mode | ✓ | ✗ | ✗ | ✓ | ✗ |
| Cross-Platform Desktop App | ✓ | ✓ | Win only | CLI only | Mac only |
| CI/CD Integration | ✓ | ✗ | ✗ | Scripting | ✗ |
| Free Tier | ✓ | ✗ | Limited | ✓ | Limited |
| Embedded Server (single binary) | ✓ | ✗ | ✗ | ✗ | ✗ |
| Web-Based UI | ✓ | ✗ | Limited | ✓ | ✗ |
| Pricing | Free / $9/mo | $50/yr | Free / $12/mo | Free | $69/yr |
curl awayAll downloads also include a standalone headless server binary in the server/ subfolder.
Actually free. No time limit, no credit card, no account required. Download the binary and use it forever. The free tier includes all core features — SSL interception, all rewrite types, all 16 throttle presets, full-text search, replay, compose, and full REST API access. You only hit limits at 500 requests/day and 5 filter rules.
Charles is a great GUI tool, but it has no API, no automation support, no CI/CD integration, and costs $50/year. ProxyCat gives you the same interception and rewrite capabilities plus 40+ REST API endpoints, so you can script your entire proxy setup. It's also cross-platform and ships as a single binary — no Java runtime needed.
Absolutely. Every download includes a headless server binary you can run without a GUI. There's also a Docker image. Set up rewrite rules, filters, and throttle profiles with curl commands in your pipeline scripts. Teams use it to mock external APIs in integration tests and simulate network failures.
Yes. ProxyCat generates its own root CA certificate on first launch. Install it on your device or browser to intercept TLS/SSL traffic. Works with iOS, Android, desktop browsers, and any HTTP client. Certificate setup takes about 30 seconds.
At 500 requests/day, new requests stop being captured but the proxy keeps working — traffic passes through normally. Your existing captures, search, and API all keep working. No forced upgrades, no nag screens. Upgrade to Pro when (and if) you need unlimited.
Yes. Rewrite rules, filter sets, and session captures can all be exported via the API and shared as JSON or .pcsession files. Pro users can save and load sessions directly. Teams typically version-control their proxy configs alongside their test suites.
Download ProxyCat, start it, and see your first captured request in under 60 seconds. Free forever. No account. No credit card. No catch.