Proxypy Web Proxy (Proxy.py) 2025 Guide: Install, MITM & Safety

Key Takeaways 

What Is Proxy.py (Proxypy Web Proxy)?

Proxy.py (also commonly searched as proxypy web proxy) is a lightweight, open-source Python proxy server used for:

• Debugging traffic

• Inspecting HTTP/HTTPS requests

• Modifying headers

• Forwarding traffic

• Creating custom proxy logic using plugins

Unlike heavy tools like Squid or Mitmproxy, proxy.py is:

• Lightweight

• Scriptable

• Fast

• Minimalist

• Easy to extend for automation

As of 2025, it’s one of the fastest Python-based proxies with a very small memory footprint (under 30MB in most use cases).

Who Uses Proxy.py in 2025?

Based on developer forums, GitHub issues, and usage trends:

• ✔ Developers debugging REST APIs
• ✔ QA teams inspecting app traffic
• ✔ Automation engineers modifying headers
• ✔ Security engineers running controlled MITM tests
• ✔ Web scrapers rotating IPs
• ✔ Researchers analyzing user agents, cookies, and payloads

It is not meant for anonymity like Tor or VPNs — it is a local debugging tool.

How Proxy.py Works (Step-by-Step Explained)

1. Client Sends Traffic to Proxy

Your browser or app sends traffic to:

2. Proxy.py Receives It

The proxy reads:

• User agent

• URL

• Headers

• Body

• Cookies

3. Traffic Gets Forwarded

Proxy.py sends the request to the intended destination (e.g., api.example.com).

4. Response Comes Back

Proxy.py receives the server’s response.

5. Response Is Returned to the Client

Optionally modified via a plugin.

6. MITM Mode (Optional)

If HTTPS MITM is enabled:

• Proxy generates certificates

• Decrypts traffic

• Re-encrypts traffic

• Sends it back

This enables full request/response inspection.

MITM Deep Dive: Why Proxy.py Can Intercept Traffic

When HTTPS MITM mode is enabled, proxy.py does a controlled man-in-the-middle operation:

🔐 Step 1 — Proxy generates a CA certificate

This acts like a fake root certificate.

🔐 Step 2 — You install that CA certificate manually

Without this, browsers will block the connection.

🔐 Step 3 — Proxy creates a certificate per domain

This is how traffic decrypting works.

🔐 Step 4 — Encrypted → Decrypted → Modified → Re-encrypted

You can:

• Inspect headers

• Edit cookies

• Rewrite responses

• Log payloads

🔒 Important: This is fully legal only when analyzing your own traffic or with permission.

Proxy.py Features & Architecture Overview

Core Features

• HTTP & HTTPS support

• MITM interception

• Plugin architecture

• High performance

• Proxy chaining

• Access control

• SOCKS proxy support

• Reverse proxy mode

Internal Architecture

Proxy.py revolves around four core classes:

• HttpParser – reads and parses requests

• TcpServer – handles TCP connections

• HttpProxyBasePlugin – plugin foundation

• Event loop – async processing for speed

It’s intentionally minimal to allow customization.

Installation Guide

Install using pip

pip install proxy.py


Verify installation

proxy --version


Install from source

git clone https://github.com/abhinavsingh/proxy.py
cd proxy.py
python setup.py install


Docker Install

Step-by-Step: Start and Use Proxy.py

Start proxy with default settings

proxy


Specify hostname & port

proxy --hostname 127.0.0.1 --port 8080


Enable MITM plugin

proxy --plugins proxy.http.proxy.HttpProxyPlugin


Show all available options

proxy --help


Useful commands

Browser & System Configuration

Chrome

Settings → Proxy → Manual Proxy →
HTTP Proxy: 127.0.0.1
Port: 8899

Firefox

Preferences → Network → Settings →
Manual Proxy Config →
127.0.0.1:8899

Python Requests

Real-World Use Cases (With Examples)

1. Debugging REST APIs

Capture request/response headers and JSON payloads.

2. Add automatic headers for testing

Example: inject a fake auth header.

3. Mobile app inspection

Proxy Android or iOS traffic through your machine.

4. QA automated tests

Rewrite URLs, throttle speed, mimic errors.

5. Blocking or redirecting traffic

Block specific hosts or MIME types.

6. Web scraping

Modify user agents, rotate IPs, analyze traffic.

Creating Custom Proxy.py Plugins (Advanced)

Proxy.py uses before_request, after_request, and handle_client_request hooks.

Basic Example Plugin

Block Certain Domains

Rewrite Response

Inject JavaScript

Performance Benchmarks (2025)

Proxy.py is not the fastest, but it is the best lightweight MITM-capable Python proxy.

Proxy Tools Compared: Features, Performance & Use Cases (2025)

DevOps Deployment

Run as systemd service

Create file:

/etc/systemd/system/proxypy.service


Add:

[Unit]
Description=Proxy.py Service
After=network.target

[Service]
ExecStart=/usr/bin/proxy –port 8899
Restart=always

[Install]
WantedBy=multi-user.target

Enable:

systemctl enable --now proxypy


Docker Compose

Security Risks, Limitations & Safe Usage

⚠ Risk 1 — MITM exposes decrypted traffic

Never use outside controlled environments.

⚠ Risk 2 — Certificate warnings

Browsers may block.

⚠ Risk 3 — Plugins can break responses

Always test carefully.

⚠ Risk 4 — Not designed for anonymity

Use VPN or Tor for anonymity, not proxy.py.

Troubleshooting Matrix

FAQs 

Q1. Is proxy.py (proxypy web proxy) safe to use?

Yes, proxy.py is safe when used locally. It becomes risky only if you enable MITM mode without installing trusted CA certificates or run it on a shared or public network. For development, debugging, and controlled environments, it is considered secure.

Q2. How do I enable MITM mode in proxy.py?

To enable MITM mode in proxy.py, run:

You must also install your generated root CA certificate on client devices for HTTPS decryption to work properly.

Q3. What port does proxy.py use by default?

Proxy.py listens on port 8899 by default.
You can change the port using:

Q4. Does proxy.py support HTTPS traffic?

Yes. Proxy.py supports HTTPS and can perform full MITM inspection, provided that CA certificates are generated and trusted on the client side. Without the certificates, only CONNECT tunneling works.

Q5. Can I use proxy.py for anonymity or privacy?

No. Proxy.py is a debugging and development proxy, not an anonymity tool. It does not hide your IP or provide privacy features like Tor or VPNs.

Q6. How do I create a custom plugin in proxy.py?

You can write a plugin by extending the base class:

from proxy.http.proxy import HttpProxyBasePlugin

class MyPlugin(HttpProxyBasePlugin):
# Override lifecycle methods such as before_upstream_connection, handle_client_request, etc.

Plugins allow header rewriting, request/response modification, logging, and custom routing.

Q7. Is proxy.py faster than mitmproxy?

Yes, for lightweight workloads.
Proxy.py is designed to be minimalistic and asynchronous, which makes it faster for:

• simple HTTP/HTTPS debugging

• routing

• filtering

• local development

However, mitmproxy is more powerful for deep traffic analysis, rich UI, scripting, and replay features.

Conclusion

Proxy.py (often searched as proxypy web proxy) remains one of the best lightweight debugging proxies in 2025. It’s fast, flexible, easy to install, and fully scriptable with Python. While not the most feature-rich, its simplicity makes it ideal for developers and QA teams needing full control over traffic inspection.

Related: Shadow Browser (2025): Proxy Safety Warnings & Shadow PC Guide

Disclaimer: This article is intended solely for technical education and authorized testing. Features such as MITM, traffic inspection, and certificate injection in Proxy.py must only be used on systems you own or where you have explicit permission. Unauthorized interception of network traffic may violate laws and organizational policies. The author and publisher disclaim any responsibility for improper or unlawful use of the information provided.