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What is Charles Proxy?

Charles Proxy is an HTTP proxy, HTTP monitor, and Reverse Proxy that enables developers to view all HTTP and SSL/HTTPS traffic between their machine and the internet. For scraping engineers, it is the foundational tool for reverse-engineering undocumented mobile APIs, inspecting TLS handshakes, and mapping the exact payload structures required to bypass client-side validation before writing a single line of extraction code.

Reverse EngineeringSSL InterceptionMobile APIsTraffic AnalysisDevTools
// 02 — definitions

Inspect the
wire.

The industry standard for man-in-the-middle (MITM) traffic inspection, turning opaque app behavior into replicable API requests.

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TL;DR

Charles Proxy sits between a client (browser or mobile app) and the server, decrypting HTTPS traffic via a custom root certificate. It is the primary reconnaissance tool used by data engineers to discover hidden API endpoints, extract hardcoded bearer tokens, and map the exact request headers needed to spoof legitimate app traffic.

01Definition & structure
Charles Proxy is a cross-platform HTTP debugging proxy application written in Java. It configures the host operating system or mobile device to route all web traffic through it. By installing a custom root certificate on the client device, Charles acts as a man-in-the-middle, decrypting outbound HTTPS requests, recording them, and re-encrypting them before forwarding them to the destination server.
02How it works in practice
An engineer configures their mobile device's Wi-Fi settings to use the IP address of the machine running Charles as its HTTP proxy. Once the Charles root certificate is installed and trusted on the mobile device, the engineer opens the target app. Every API call, image fetch, and analytics ping appears in the Charles interface in real-time, exposing the exact JSON payloads, headers, and authentication tokens the app uses.
03Mobile API interception
Mobile apps are the richest source of clean, structured data because they rely on dedicated JSON APIs rather than HTML rendering. However, modern apps employ SSL pinning to prevent MITM attacks. Intercepting these requires a rooted device and dynamic instrumentation tools to disable the pinning checks, allowing Charles to capture the traffic.
04How DataFlirt uses it
We use Charles Proxy exclusively during the scoping and integration phase. When a client requests data from a complex platform, our engineers route the platform's mobile app through Charles to discover undocumented APIs. These APIs are often faster, more structured, and less heavily protected by anti-bot systems than their web counterparts. Once the API contract is mapped, we build the production scraper to interact directly with those endpoints.
05Did you know?
Charles Proxy has been actively maintained since 2004. Despite the rise of modern, CLI-first alternatives like mitmproxy, Charles remains the industry standard for visual traffic inspection due to its robust tree-view interface, reliable SSL proxying, and powerful rewrite rules that allow engineers to modify traffic on the fly without writing custom scripts.
// 03 — the interception model

Measuring API
discovery.

Before a pipeline is written, the target's API surface must be mapped. These metrics define the reconnaissance phase of a new DataFlirt integration.

API Coverage = C = endpoints_mapped / total_app_views
1.0 means full replication of app functionality via direct API calls. DataFlirt scoping metrics
SSL Pinning Bypass Effort = E = apk_decompile + frida_hooks + charles_cert
Required when standard MITM fails on modern mobile apps. Reverse engineering workflow
Payload Replication Accuracy = A = 1 − (failed_requests / total_spoofed_requests)
Validating that the extracted headers work outside of Charles. Pipeline testing phase
// 04 — charles session trace

Decrypting a mobile
pricing API.

A live view of Charles intercepting an iOS e-commerce app. The custom root certificate decrypts the TLS payload, revealing the undocumented JSON endpoint.

SSL ProxyingiOS AppJSON Response
edge.dataflirt.io — live
CAPTURED
// connection established
client: "192.168.1.42 (iPhone)"
target: "api.target-ecommerce.com:443"
ssl_handshake: ok // charles root cert accepted

// intercepted request
method: "POST /v3/catalog/pricing"
header.x-app-version: "4.12.0"
header.authorization: "Bearer eyJhbG..." // extracted
header.x-signature: "a9f8b7c6d5e4..." // dynamic hash

// decrypted payload
request.body: {"sku": "IPH-15-PRO", "region": "IN"}

// server response
status: 200 OK
response.body: {"price": 134900, "currency": "INR", "stock": 14}
action: mapped to pipeline schema
// 05 — reconnaissance hurdles

Why interception
fails.

Setting up Charles is easy; getting modern apps to trust it is hard. Ranked by frequency of interception failure during DataFlirt's pipeline scoping phase.

SCOPING JOBS ·  ·  ·  ·   450+ mobile apps
SUCCESS RATE ·  ·  ·  ·   98.2%
UPDATED ·  ·  ·  ·  ·  ·  2026-05-19
01

SSL Certificate Pinning

requires Frida/Objection · App rejects the Charles root certificate
02

Dynamic Request Signatures

HMAC hashes · Payloads tied to timestamp or device state
03

Mutual TLS (mTLS)

client certificates · Server requires a hardcoded client cert
04

Non-HTTP Protocols

gRPC / WebSockets · Custom TCP binary protocols evade standard HTTP proxies
05

Root/Jailbreak Detection

app crashes · App refuses to run in the interception environment
// 06 — pipeline scoping

Reverse engineer first,

automate second.

At DataFlirt, we never write a scraper by guessing DOM selectors if an underlying API exists. Charles Proxy is the first tool deployed when scoping a new target. By routing the target's mobile app or frontend through our interception environment, we map the raw JSON endpoints, extract the authentication flows, and isolate the exact headers required to spoof legitimate traffic. An hour in Charles saves weeks of pipeline maintenance.

Reconnaissance Session

Output from a Charles Proxy scoping session on a B2B delivery app.

target.app com.b2b.delivery.v4
ssl.pinning bypassed · frida-server
endpoints.discovered 14 hidden APIs
auth.mechanism JWT + static API key
rate.limits 100 req/min per IP
schema.mapped true
pipeline.status ready for dev

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// 07 — FAQ

Common
questions.

About traffic interception, SSL pinning, legal considerations, and how DataFlirt uses Charles Proxy in the pipeline lifecycle.

Ask us directly →
Is using Charles Proxy to inspect app traffic legal? +
Inspecting traffic originating from your own device is generally legal and falls under standard security research and reverse engineering practices. However, using the discovered APIs to extract data at scale depends on the target's Terms of Service and whether the API requires authentication. We strictly adhere to authorized access boundaries during scoping.
How do you bypass SSL pinning in modern mobile apps? +
Charles Proxy alone cannot bypass SSL pinning. When an app is pinned, it only trusts a specific certificate hash, ignoring the device's trusted root store. We use rooted Android or jailbroken iOS devices running dynamic instrumentation frameworks like Frida or Objection to hook the app's SSL verification methods at runtime, forcing it to accept the Charles certificate.
Why use Charles instead of Chrome DevTools? +
Chrome DevTools is excellent for web applications, but it cannot capture traffic from native desktop apps, mobile applications, or background OS services. Charles acts as a system-wide proxy, capturing everything. It also provides advanced features like Map Local and Rewrite, allowing engineers to modify requests and responses on the fly to test API boundaries.
Can Charles Proxy decrypt all HTTPS traffic? +
Only if the client trusts the Charles Root Certificate. If the client uses Mutual TLS (mTLS) where the server demands a specific client certificate, or if strict SSL pinning is enforced and not bypassed, the TLS handshake will fail and the connection will drop before any HTTP data is transmitted.
How does DataFlirt use Charles Proxy in production? +
We don't use Charles Proxy in production pipelines. Charles is strictly a reconnaissance and development tool. We use it during the initial scoping phase to map APIs and understand authentication flows. The production pipelines are written in Go or Python, directly implementing the network requests discovered via Charles, ensuring high throughput and low overhead.
What is the Map Local tool in Charles? +
Map Local allows you to serve a local file as the response to a specific intercepted request. This is highly useful for testing how a client application handles malformed data, unexpected schema changes, or rate-limit responses without actually triggering those conditions on the live server.
$ dataflirt scope --new-project --target=charles-proxy READY

Tell us what
to extract.
We do the rest.

20-minute scoping call. Pilot dataset within the week. Production within two. Whether you need a one-off catalogue dump or a continuous feed across millions of records — we scope, build, and operate the pipeline.

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hello@dataflirt.com  ·  Bengaluru  ·  IST  ·  typical reply < 4h
// 08 — keep reading

Related glossary terms

DevTools

Mitmproxy

An open-source, CLI-first alternative to Charles Proxy often used in automated testing.

Read →
Mobile Scraping

Mobile API Interception

The broader practice of capturing and reverse-engineering mobile app traffic.

Read →
DevTools

Fiddler

A popular web debugging proxy similar to Charles, heavily used in the Windows ecosystem.

Read →
Network Layer

TLS Fingerprinting

How servers detect that your automated script isn't the native app you reverse-engineered.

Read →