claude-skills is a collection of specialized skills that extends Claude Code for full-stack development. Developers use it for programming languages, frameworks, infrastructure, APIs, testing, DevOps, security, data and machine learning, platform tasks, and project workflows.
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 Jeffallan/claude-skills --skill fullstack-guardiangit clone --depth 1 https://github.com/Jeffallan/claude-skillsWrote 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/jeffallan/claude-skills/fullstack-guardian)<a href="https://agentmods.dev/skills/jeffallan/claude-skills/fullstack-guardian"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/fullstack-guardian/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/jeffallan/claude-skills/fullstack-guardian"><img src="https://agentmods.dev/badge/skills/jeffallan/claude-skills/fullstack-guardian.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- Socket pass
- 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 | $0.00164 | $0.01227 |
| Opus 5 | $0.00082 | $0.00613 |
| Sonnet 5 | $0.00033 | $0.00245 |
| Haiku 4.5 | $0.00016 | $0.00123 |
Grade A, and why
fullstack-guardian scanned grade A with 0 findings 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 9d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- fullstack-guardian — 89% identical, 6 lines differ
How it starts
The opening of the file, as written. The whole thing — 108 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Fullstack Guardian
Security-focused full-stack developer implementing features across the entire application stack.
Core Workflow
- Gather requirements - Understand feature scope and acceptance criteria
- Design solution - Consider all three perspectives (Frontend/Backend/Security)
- Write technical design - Document approach in
specs/{feature}_design.md - Security checkpoint - Run through
references/security-checklist.mdbefore writing any code; confirm auth, authz, validation, and output encoding are addressed - Implement - Build incrementally, testing each component as you go
- Hand off - Pass to Test Master for QA, DevOps for deployment
Reference Guide
Load detailed guidance based on context:
| Topic | Reference | Load When |
|---|---|---|
| Design Template | references/design-template.md |
Starting feature, three-perspective design |
| Security Checklist | references/security-checklist.md |
Every feature - auth, authz, validation |
| Error Handling | references/error-handling.md |
Implementing error flows |
| Common Patterns | references/common-patterns.md |
CRUD, forms, API flows |
| Backend Patterns | references/backend-patterns.md |
Microservices, queues, observability, Docker |
| Frontend Patterns | references/frontend-patterns.md |
Real-time, optimization, accessibility, testing |
| Integration Patterns | references/integration-patterns.md |
Type sharing, deployment, architecture decisions |
| API Design | references/api-design-standards.md |
REST/GraphQL APIs, versioning, CORS, validation |
| Architecture Decisions | references/architecture-decisions.md |
Tech selection, monolith vs microservices |
| Deliverables Checklist | references/deliverables-checklist.md |
Completing features, preparing handoff |
Constraints
MUST DO
- Address all three perspectives (Frontend, Backend, Security)
- Validate input on both client and server
- Use parameterized queries (prevent SQL injection)
- Sanitize output (prevent XSS)
- Implement proper error handling at every layer
- Log security-relevant events
- Write the implementation plan before coding
- Test each component as you build
What ships with it
10 files 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.
- references/api-design-standards.md 7.6 KB
- references/architecture-decisions.md 12 KB
- references/backend-patterns.md 5.9 KB
- references/common-patterns.md 3.1 KB
- references/deliverables-checklist.md 8.6 KB
- references/design-template.md 2.1 KB
- references/error-handling.md 3.3 KB
- references/frontend-patterns.md 8.6 KB
- references/integration-patterns.md 8.1 KB
- references/security-checklist.md 2.5 KB
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.
- 9d ago First seen · 108 lines · 164 tokens per session scan A 22a1c39c86be
fullstack-guardian is a skill published in the GitHub repository Jeffallan/claude-skills (11,361 stars, last pushed 1mo ago), licensed MIT. It adds 164 tokens to every session and 1,227 once invoked, about $0.0008 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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add-react-i18n
Add react-i18next internationalization to a React NPM library package. Creates isolated i18n instance, translation files, modifies provider and components. Use when the user wants to add multi-language support to a React component library.
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react-alert
Display user-facing alerts, notifications, and feedback messages using toast notifications from the sonner library. Use this skill whenever the user asks to show an alert, notification, success message, error message, warning, or any kind of user feedback popup.
react-architecture
Create the complete frontend architecture for a new entity in the React application. Generates TypeScript types, service class, context provider, custom hook, and registers the provider in main.tsx. Use this skill when the user asks to create a new entity, feature module, or domain area in the frontend.