Strix is an open-source penetration-testing tool that uses autonomous AI agents to inspect applications, exploit vulnerabilities, and validate findings with working proofs of concept. Developers and security teams use it for application security testing, bug-bounty research, remediation guidance, reporting, and automated checks in development pipelines.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add usestrix/strix --skill api-security-testinggit clone --depth 1 https://github.com/usestrix/strixWrote 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.
[](https://agentmods.dev/skills/usestrix/strix/api-security-testing)<a href="https://agentmods.dev/skills/usestrix/strix/api-security-testing"><img src="https://agentmods.dev/badge/skills/usestrix/strix/api-security-testing/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.
<a href="https://agentmods.dev/skills/usestrix/strix/api-security-testing"><img src="https://agentmods.dev/badge/skills/usestrix/strix/api-security-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket warn
- Snyk pass
- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00144 | $0.01508 |
| Opus 5.5 | $0.00058 | $0.00603 |
| Sonnet 5.5 | $0.00029 | $0.00302 |
| Haiku 4.5 | $0.00014 | $0.00151 |
Grade A, and why
api-security-testing 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 28d ago.
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.
`strix_runs/<run>/penetration_test_report.md` first, then `vulnerabilities/*.md` — each contains the exact request that proved the issue. Replay it (for example, with `curl`) before reporting; for authorization findings, How it starts
The opening of the file, as written. The whole thing — 62 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Security-test an API
APIs fail differently from web UIs: there is no rendered surface to crawl, the interesting bugs are authorization-shaped rather than injection-shaped, and the same endpoint behaves differently per token. This workflow targets those specifics with Strix's autonomous agents, using the current OWASP API Security Top 10 (2023) as the coverage checklist. For the web-app equivalent, the current edition is the OWASP Top 10:2025 — see owasp-top-10-testing.
Install, LLM setup, full CLI flags, and the managed-cloud path are in the penetration-testing-with-strix skill. Read it if strix --version fails or the target is not an API. For a run with no Docker and no LLM key, the same binary drives the managed platform: strix cloud login, then strix cloud scans start ... (details in managed-pentesting-with-strix).
1. Gather what the agents need
APIs are near-impossible to test blind, so collect first:
| Input | Why it matters |
|---|---|
Schema — OpenAPI/Swagger file, Postman collection, GraphQL endpoint (introspection), or a gRPC .proto |
Turns guesswork into full endpoint enumeration. Biggest single win in coverage. An OpenAPI/Swagger or Postman spec (.json/.yaml/.yml) is a target Strix takes directly; a .proto is not, so pass it with --workspace-file. |
| Two sets of credentials/tokens, ideally in different tenants | BOLA/IDOR — API1:2023, still the #1 API risk — can only be proven by accessing tenant A's objects with tenant B's token. |
| A low-privilege and a high-privilege token | Required to prove broken function-level authorization (API5:2023 — a user calling admin-only routes). |
| Example object IDs | Lets agents test ID tampering immediately instead of hunting for valid identifiers. |
| Out-of-scope routes | Payments, mass notification, destructive admin endpoints. |
| Rate limits / WAF in front of the API | Avoids agents burning budget on throttled requests; mention them so testing adapts. |
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.
- 28d ago Changed bd04c90d87be
- 1mo ago Changed 5d978e5f05f5
- 1mo ago First seen · 62 lines · 144 tokens per session scan A 720eb63825ed
api-security-testing is a skill published in the GitHub repository usestrix/strix (68,829 stars, last pushed today), licensed Apache-2.0. It adds 144 tokens to every session and 1,508 once invoked, about $0.0006 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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