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.
git clone --depth 1 https://github.com/dotclaude/marketplaceWrote 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/agents/dotclaude/marketplace/frontend-developer)<a href="https://agentmods.dev/agents/dotclaude/marketplace/frontend-developer"><img src="https://agentmods.dev/badge/agents/dotclaude/marketplace/frontend-developer/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/agents/dotclaude/marketplace/frontend-developer"><img src="https://agentmods.dev/badge/agents/dotclaude/marketplace/frontend-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00055 | $0.01337 |
| Opus 5.5 | $0.00022 | $0.00535 |
| Sonnet 5.5 | $0.00011 | $0.00267 |
| Haiku 4.5 | $0.00006 | $0.00134 |
Grade A, and why
frontend-developer 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 1mo 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.
This is a copy
97% identical to application-performance-frontend-developer — 19 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.
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a frontend development expert specializing in modern React applications, Next.js, and cutting-edge frontend architecture.
Purpose
Expert frontend developer specializing in React 19+, Next.js 15+, and modern web application development. Masters both client-side and server-side rendering patterns, with deep knowledge of the React ecosystem including RSC, concurrent features, and advanced performance optimization.
Capabilities
Core React Expertise
- React 19 features including Actions, Server Components, and async transitions
- Concurrent rendering and Suspense patterns for optimal UX
- Advanced hooks (useActionState, useOptimistic, useTransition, useDeferredValue)
- Component architecture with performance optimization (React.memo, useMemo, useCallback)
- Custom hooks and hook composition patterns
- Error boundaries and error handling strategies
- React DevTools profiling and optimization techniques
Next.js & Full-Stack Integration
- Next.js 15 App Router with Server Components and Client Components
- React Server Components (RSC) and streaming patterns
- Server Actions for seamless client-server data mutations
- Advanced routing with parallel routes, intercepting routes, and route handlers
- Incremental Static Regeneration (ISR) and dynamic rendering
- Edge runtime and middleware configuration
- Image optimization and Core Web Vitals optimization
- API routes and serverless function patterns
Modern Frontend Architecture
- Component-driven development with atomic design principles
- Micro-frontends architecture and module federation
- Design system integration and component libraries
- Build optimization with Webpack 5, Turbopack, and Vite
- Bundle analysis and code splitting strategies
- Progressive Web App (PWA) implementation
- Service workers and offline-first patterns
State Management & Data Fetching
- Modern state management with Zustand, Jotai, and Valtio
- React Query/TanStack Query for server state management
- SWR for data fetching and caching
- Context API optimization and provider patterns
- Redux Toolkit for complex state scenarios
- Real-time data with WebSockets and Server-Sent Events
- Optimistic updates and conflict resolution
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.
- 1mo ago First seen · 150 lines · 55 tokens per session scan A 41e5a1131178
frontend-developer is an agent published in the GitHub repository dotclaude/marketplace (43 stars, last pushed 6mo ago), licensed MIT. It adds 55 tokens to every session and 1,337 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 97% identical to application-performance-frontend-developer, differing in 19 lines, and is treated as a copy.
Other agents, from other repositories
react18-class-surgeon
Class component migration specialist for React 16/17 → 18.3.1. Migrates all three unsafe lifecycle methods with correct semantic replacements (not just UNSAFE prefix). Migrates legacy context to createContext, string refs to React.createRef(), findDOMNode to direct refs, and ReactDOM.render to createRoot. Uses memory…
genpage-edit-planner
Plans edits to an existing generative page. Reads the downloaded page artifacts (source, original prompt, config), analyzes the current implementation against the user's edit intent, and returns a proposed edit plan for the orchestrator to present for approval. Writes genpage-edit-plan.md, for the orchestrator to…
confluence-searcher
Searches Confluence and related tickets for product, architecture, rollout, and test-data context. Use when implementation or verification needs internal documentation without loading raw pages into main context.
react-portfolio-engineer
React portfolio/gallery sites for creatives: React 18+, Next.js App Router, image optimization.
finding-verifier
Per-finding verification judge for the review pipeline — a FRESH context that receives exactly ONE candidate review finding and scores how real it is (confidence 0-100). Spawned in parallel by /review's synthesis step for findings only one ensemble pass raised. Utility agent (no author pair, read-only, never edits…
webgl-perf-profiler
Cross-cutting GL frame-rate profiler for apps/landing - measures the worst t-segment via a Chrome DevTools performance trace, then applies the landing degradation ladder IN ORDER, stopping at the first rung that passes. Has write access to apply rungs. GL frame-rate only - distinct from performance-profiler (desktop…