api-security-testing skill: pentest REST, GraphQL and gRPC APIs with Strix

Makes your agent run Strix against your API and report OWASP API Top 10 flaws, each with a working proof-of-concept request.

Installs: 14.4K; on skills.sh
Stars: 73.2K; on GitHub
Updated: Oct 2026; last repo commit

This skill makes your agent gather what an API pentest needs (a schema, two sets of tokens, example IDs, out-of-scope routes), run Strix against the API, and replay each proof before it reports a finding. It uses the OWASP API Security Top 10 (2023) as its coverage checklist.

It triggers when you ask to pentest, security-test or audit an API or backend service. It needs the Strix command line, Docker running and an LLM API key, or the managed Strix cloud.

Good for

Backend developers testing an API for cross-tenant data access
Security engineers checking authorization on REST, GraphQL or gRPC
Teams who have an OpenAPI, Postman or GraphQL schema to feed a scan

Install api-security-testing

Claude Code

Copy this prompt.

Install the api-security-testing skill in Claude Code. Run this command:

npx skills add usestrix/strix --skill api-security-testing --skill penetration-testing-with-strix

Then check that it loaded and tell me how to use it.

2
Paste it into Claude Code. It shows the change and asks before running it.

Requires Node.js.

The skill only drives the Strix command line, so install Strix too: it needs Docker running and an LLM key set in the two variables listed here. api-security-testing tells the agent to read penetration-testing-with-strix for install and flags, which is why the first command adds both. pipx install strix-agent is the other route named in that skill. The Strix README says to test only systems you own or have written permission to test.

From its listing on skills.sh. Source.

What's in the skill

When it loads

Security-test a REST, GraphQL, or gRPC API with Strix — autonomous agents that enumerate endpoints from an OpenAPI/GraphQL schema (or by crawling), then actually exploit the API-specific vulnerability classes in the OWASP API Security Top 10 (2023) — broken object-level authorization (BOLA/IDOR), broken object property level authorization (excessive data exposure and mass assignment), broken function-level authorization, unrestricted resource consumption, SSRF, injection, and auth/token flaws. Every finding comes with a working proof-of-concept request. Use when the user asks to pentest, security-test, audit, or find vulnerabilities in an API, endpoint, or backend service.

Sections in SKILL.md

1. Gather what the agents need
2. Run the scan
3. Verify findings
4. Fix, re-test, and keep it tested

Key facts

Author: usestrix (SKILL.md metadata author; Strix maintainers)
Repo: usestrix/strix, folder skills/api-security-testing
Installs on skills.sh: 14,427 as of 2 Nov 2026
GitHub stars: 73,211 for the whole usestrix/strix repo, 2 Nov 2026
License: Apache-2.0
Last commit in the repo: 2026-10-30
What is inside: 1 file (SKILL.md only)
skills.sh audits: Gen Agent Trust Hub pass, Socket warn, Snyk pass
Needs: Strix CLI, Docker, an LLM API key (or a Strix cloud account)
Pairs with: penetration-testing-with-strix for install and flags; fix-security-vulnerabilities-with-strix and ci-security-scanning-with-strix for later steps

What it includes

Collects schema, two tokens, example IDs and out-of-scope routes
It asks for an OpenAPI, Postman or GraphQL schema, tokens for two tenants, a low and a high privilege token, example object IDs, and routes that are off limits. It will not make up tokens.
Read · 1. Gather inputs
Runs strix -n with the spec as a target and a budget cap
Passes the spec as a target, not as prose, with the tokens and focus in --instruction. Covers BOLA, function-level and property-level authorization, resource consumption, SSRF and injection.
Try: “Security-test our API at api.staging.example.com using ./openapi.yaml. I will give you tokens for two orgs.”
Runs code · 2. Run the scan
Takes Postman collections, GraphQL endpoints and .proto files
A Postman export works as a target, and postman://<uuid> pulls one live using POSTMAN_API_KEY. A gRPC .proto is passed with --workspace-file.
Network · Postman and gRPC inputs
Reads the report and replays each request before reporting
Reads penetration_test_report.md and vulnerabilities/*.md, replays the proving request, and confirms authorization findings contain the other tenant's data. Also writes findings.sarif and vulnerabilities.json.
Files · 3. Verify findings
Points to the fix and CI skills
Hands off to fix-security-vulnerabilities-with-strix, then re-runs against the same target. ci-security-scanning-with-strix adds pull-request testing. Both are separate skills.
Read · 4. Fix, re-test, keep tested

From the official docs

Permissions

High risk

What it can do

Read your data
Create and change things
Delete things
Read-only mode

Watch out for

It sends real attacks and can change data
The SKILL.md says the agents actually exploit the API vulnerability classes, and tells the agent not to scan an API the user does not own. The Strix README says to test only systems you own or have explicit written permission to test. Our advice: run it against staging, not production. github.com
A scan spends your LLM budget
Strix runs on your own LLM key. Always set --max-budget, as the skill says. A clean result is not proof of full coverage, because a scan that hits its cap wraps up early and can still exit 0. github.com
The install is a piped shell script
If strix is missing, the penetration-testing-with-strix skill runs the strix.ai installer script or pipx. Read the script first, or install Strix yourself. github.com
A local path is mounted writable
A path passed with -t goes into the sandbox writable, so the agents can read and change it. Point at a clean checkout, not uncommitted work. github.com
Tokens end up in your command
Tokens for several tenants go into --instruction. The SKILL.md says to keep tokens out of shell history and out of committed files, and to use --instruction-file when the block gets long. Our advice: use short-lived test tokens. github.com
An optional Postman key pulls collections live
A postman:// target needs POSTMAN_API_KEY in the environment. Use a collection export file if you do not want to set it. github.com

Technical details

Turning on read-only	The SKILL.md defines no read-only switch.
Talks to	The API you name (real exploit requests). Your LLM provider, set by STRIX_LLM and LLM_API_KEY. Postman, only with a postman:// target and POSTMAN_API_KEY. strix.ai installer, and app.strix.ai if you use the cloud route
Scopes	Runs the strix command in a Docker sandbox Sends exploit requests to the API you name Writes reports, findings.sarif and vulnerabilities.json under strix_runs/ Uses tokens you pass in --instruction

Questions

What does the api-security-testing skill do?

It makes your agent pentest a REST, GraphQL or gRPC API with Strix. It gathers a schema and tokens, runs the scan, and reports findings with a working proof-of-concept request.

How do I install it?

Use the install box on this page. You need the skill, the Strix command line, Docker running and an LLM API key. The skill points to penetration-testing-with-strix for install details, so the box adds that skill too.

What do I need to give it?

A schema (OpenAPI, Postman or GraphQL; a gRPC .proto goes in as a workspace file), tokens for two tenants, a low and a high privilege token, example IDs, and routes that are out of scope.

Does it need a Postman key?

Only to pull a collection live with a postman:// target, which needs POSTMAN_API_KEY in the environment. A collection exported to a file does not need it.

Can I test an API on a private network?

The skill points to the managed Strix platform and its network connector for internal APIs that your machine cannot reach.

Is it safe to run?

Treat it as an active attack tool. The agents send real exploit requests, the SKILL.md says not to scan an API you do not own, and the Strix README says to test only systems you own or have written permission to test. Our advice: use staging, test tokens and a budget cap. See the Watch out list.

Information

updated Nov 2, 2026

Repository: usestrix/strix
Folder: skills/api-security-testing

usestrix/strix skills.sh

Sources

Docs, issue trackers and discussions this page is built from.

Show all 3

Strix README · github.com
penetration-testing-with-strix SKILL.md · github.com
api-security-testing SKILL.md · github.com