Charles Proxy

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Introduction

Charles is an HTTP proxy, HTTP monitor and reverse proxy that lets a developer view all HTTP and SSL/HTTPS traffic between their machine and the internet, including requests, responses and headers, according to its homepage. It runs on Windows, macOS and Linux and has been a staple of web and mobile debugging for many years.

Testers use Charles to inspect API calls from browsers and mobile devices, throttle bandwidth to simulate slow networks, rewrite requests and responses, map remote URLs to local files, set breakpoints, and repeat requests to check server behaviour.

Charles 5 was released on 12 March 2025, and the site lists Charles 5.1 with performance and UI improvements. Licences are sold per user after a 30-day free trial.

In the quality loop it supports manual and exploratory testing of network behaviour.

Features

1. SSL proxying: Inspect HTTPS traffic.
2. Throttling: Simulate slow or lossy networks.
3. Rewrite and Map: Change requests and responses or map to local files.
4. Breakpoints: Pause and edit traffic.
5. Repeat requests: Re-send for quick server checks.

Pros

1. Mature: Long history and lots of community guides.

Cons

1. Dated UI: Older interface than newer proxies.
2. Paid licence: After the 30-day trial.

Usage and Links (Example)

Start Charles, install the Charles root certificate on your device, enable SSL proxying for the API host, and use Throttle Settings to test the app on a 3G-like connection.

Resources:

• Charles Proxy website

Pricing

30-day free trial; licences USD $50 each for 1-4 users, with volume discounts. See site.

Recommended for?

1. Web and mobile testers checking network behaviour.
2. Not a fit for automated test pipelines.

Conclusion

Charles remains a dependable, widely known debugging proxy for manual network testing.

On CheckOps, Charles Proxy is filed under the API & contract testing and Integration testing stages. Related tools listed here include Proxyman, HTTP Toolkit, Fiddler, mitmproxy, Requestly and Burp Suite. Before choosing, compare them on licence, supported languages and platforms, hosting model, and how well each fits your existing CI pipeline. Facts on this page were checked against the official website, documentation and repository on 11 November 2026; statements the vendor makes about its own product are marked as vendor claims.