API Testing — Deep Dive

API Testing — Deep Dive is a skill for Claude Code from akashrpatil/awesome-offensive-security-skills. It costs 25 tokens per session (1,006 once invoked), scanned A, a copy of Access Control — Complete Deep Dive, Apache-2.0.

A detailed guide to testing web APIs, which are interfaces that let software exchange requests and data. It uses PortSwigger training labs and includes example requests, payloads, bypass methods, and advanced exploitation techniques.

In plain words
What is it for?
Preparing for BSCP certification, practising bug-bounty testing, finding API weaknesses, testing filters and web-application firewalls, and combining multiple vulnerabilities in a controlled lab.
Why use it?
It gives security testers a structured way to practise finding and exploiting weaknesses in APIs. The lab examples help explain how issues such as hidden endpoints and unexpected parameters can affect an application.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: positional $N argument.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is - [`_shared/references/elite-chaining-strategy.md`](../_shared/references/elite-chaining-strategy.md) — Exploit chaining methodology and high-payout chain patte.

Part of the cyberskills-elite plugin — 191 skills shipped together

Good fit Preparing for BSCP certification, practising bug-bounty testing, finding API weaknesses, testing filters and web-application firewalls, and combining multiple vulnerabilities in a controlled lab.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/akashrpatil/awesome-offensive-security-skills
agentmods
npx agentmods add skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs

Made for: Claude Code.

Or install cyberskills-elite, the plugin that ships this one along with the rest of its 191 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for API Testing — Deep Dive

README.md
[![agentmods](https://agentmods.dev/badge/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs/github.svg)](https://agentmods.dev/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs)
Your own site
<a href="https://agentmods.dev/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs"><img src="https://agentmods.dev/badge/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for API Testing — Deep Dive

Your own site · 80×15
<a href="https://agentmods.dev/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs"><img src="https://agentmods.dev/badge/skills/akashrpatil/awesome-offensive-security-skills/api-testing-labs.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,006 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin 75% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00025 $0.01006
Opus 5 $0.00013 $0.00503
Sonnet 5 $0.00005 $0.00201
Haiku 4.5 $0.00003 $0.00101

Measured 10d ago against content hash 1cb8004c00b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

API Testing — Deep Dive scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/process.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

tools: [burp-suite, curl, sqlmap, ffuf, python, hashcat, ysoserial]
Origin

This is a copy

75% identical to Access Control — Complete Deep Dive — 84 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

skills/bug-hunting/deep-dive-labs/api-testing-labs/SKILL.md · 127 lines

How it starts

The opening of the file, as written. The whole thing — 127 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Testing — Deep Dive

Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. 🟢 Apprentice 🟡 Practitioner 🔴 Expert

When to Use

  • BSCP certification prep
  • Real-world bug bounty hunting
  • Building exploitation chains
  • Understanding bypass techniques

Prerequisites

  • Burp Suite Professional
  • Burp Collaborator / interactsh
  • Browser with proxy configured

Workflow

Phase 1: Reconnaissance

  • Identify input vectors, parameters, and application behavior.

Phase 2: Exploitation

  • Apply standard lab payloads.

Phase 3: Zero-Day Escalation

  • Fuzz filters, bypass WAFs, and chain with other vulns.

Lab Playbooks

Lab 1: Exploiting documentation 🟢 APPRENTICE

Find /api docs endpoint → discover /api/user/carlos DELETE endpoint → delete user.

Lab 2: Server-side param pollution query 🟡 PRACTITIONER

POST /forgot-password HTTP/1.1

username=administrator%26field=reset_token

%26 = & → injects additional parameter into server-side API call → leaks reset token.

Lab 3: Unused API endpoint 🟡 PRACTITIONER

Change GET /api/products/1/price to PATCH method:

{"price":0}

→ Buy product for $0.

Lab 4: Mass assignment 🟡 PRACTITIONER

{"chosen_discount":{"percentage":100}}

Include discount object in checkout request → 100% discount applied.

Lab 5: Param pollution REST URL 🟡 PRACTITIONER

username=administrator#

Server constructs: /api/users/administrator#/field# truncates path → returns full user object with token.

Blue Team Detection

  • Monitor access logs for anomalous payloads.
  • Implement strict input validation and parameterized queries where applicable.
  • Create WAF rules masking generic attack patterns.

Zero-Day Research

When standard technique fails:

  1. Identify the filter/WAF
  2. Fuzz with Burp Intruder custom wordlists
  3. Search GitHub/Twitter for new bypasses
  4. Chain with other vulns for escalation
  5. Try encoding variants: URL, double-URL, unicode, hex

Read the full file on GitHub · 127 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 127 lines · 25 tokens per session scan A 1cb8004c00b9

Subscribe to this mod's changes

API Testing — Deep Dive is a skill published in the GitHub repository akashrpatil/awesome-offensive-security-skills (4 stars, last pushed 4mo ago), licensed Apache-2.0. It adds 25 tokens to every session and 1,006 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). It is 75% identical to Access Control — Complete Deep Dive, differing in 84 lines, and is treated as a copy.