httpmon vs Charles Proxy
The Best Open-Source
Charles Proxy Alternative
Same HTTPS interception and debugging you're used to, plus gRPC decoding, vim navigation, and scripting. No Java, no $50 license.
Why switch from Charles Proxy to httpmon?
Charles has been around for a long time, and it works. But it runs on Java (slow to start, hungry for RAM), can't decode gRPC or Protobuf, has no scripting, and costs $50. httpmon does all the same core debugging in your terminal — faster, lighter, and free.
Feature Comparison
| Feature | httpmon | Charles Proxy |
|---|---|---|
| Price | Free (MIT) | $50 one-time |
| Open source | ✅ Full source | ❌ Proprietary |
| Terminal-native | ✅ Runs in terminal | ❌ GUI only (Java/Swing) |
| Vim keybindings | ✅ Full vim navigation | ❌ Mouse-driven |
| HTTPS interception | ✅ Auto CA certs | ✅ Manual setup |
| gRPC decoding | ✅ Built-in | ❌ Not supported |
| Protobuf decoding | ✅ Built-in | ❌ Not supported |
| HAR export | ✅ | ✅ |
| JavaScript scripting | ✅ JS hooks | ❌ No scripting |
| Network throttling | ✅ Built-in presets | ✅ Throttle settings |
| MCP server (AI) | ✅ --mcp flag | ❌ |
| Diff view | ✅ Side-by-side | ❌ |
| macOS support | ✅ | ✅ |
| Linux support | ✅ | ✅ |
| Startup time | Instant (Go binary) | Slow (Java VM) |
| Memory usage | Low (~20 MB) | High (~200+ MB) |
What makes httpmon different
No Java
Charles runs on the JVM — 200+ MB of RAM, seconds to start. httpmon is a Go binary. It starts instantly and barely touches your memory.
Vim keybindings
Filter, inspect, and navigate traffic without touching the mouse. If you already live in the terminal, httpmon fits right in.
gRPC & Protobuf decoding
Charles can't decode gRPC or Protobuf at all. httpmon shows gRPC, gRPC-Web, and Protobuf bodies as readable JSON, with or without .proto files.
Actually free
MIT license. No nag screen asking you to buy a $50 license every time you launch it.
FAQ
Frequently Asked Questions
Is httpmon a good replacement for Charles Proxy?
It covers the core stuff — HTTPS interception, request inspection, HAR export, throttling — and adds gRPC/gRPC-Web/Protobuf decoding, JS scripting, vim navigation, and an MCP server. The main trade-off: it's terminal-only, so no point-and-click GUI.
Does httpmon require Java like Charles Proxy?
No. It's a single Go binary. No JVM, no startup lag, and it uses ~20 MB instead of the 200+ MB Charles needs.
Can httpmon intercept HTTPS traffic like Charles?
Same idea — MITM proxy with CA certificate generation. httpmon handles the cert setup automatically. Traffic shows up decrypted in plain text.
Does httpmon support gRPC? Charles doesn't.
Charles has no gRPC or Protobuf support at all. httpmon decodes gRPC, gRPC-Web, and Protobuf natively. Pass --proto-path for field names, or it'll decode the raw wire format with field numbers.
Is httpmon really free?
MIT license, no trial, no license keys. Charles costs $50 per seat.