What is clerk-frontend-sdks?

A skill for connecting Clerk, an authentication service, to frontend applications built with React, Vue, Nuxt, Astro, Expo, React Router, TanStack React Start, or plain JavaScript.

Use it when adding sign-in, sign-up, user controls, profiles, organization switching, or Clerk authentication context to a frontend app.

It helps choose the right framework SDK and correctly set up providers, keys, redirects, and client authentication state. It also warns that frontend sign-in state is not the same as server-side permission checks.

clerk-frontend-sdks — Skill for Claude Code by JosiahSiegel

Install

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.

Any agent

npx skills add JosiahSiegel/claude-plugin-marketplace --skill clerk-frontend-sdks

Clone the repo

git clone --depth 1 https://github.com/JosiahSiegel/claude-plugin-marketplace

Made for: Claude Code.

Or install clerk-auth-master, the plugin that ships this one along with the rest of its 4 skills, 1 agent.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks/github.svg)](https://agentmods.dev/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks)

Your own site

<a href="https://agentmods.dev/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks"><img src="https://agentmods.dev/badge/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks"><img src="https://agentmods.dev/badge/skills/josiahsiegel/claude-plugin-marketplace/clerk-frontend-sdks.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 132 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,905 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found 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.

Model	Per session	Once invoked
Fable 5.1	$0.00132	$0.01905
Opus 5.5	$0.00053	$0.00762
Sonnet 5.5	$0.00026	$0.00381
Haiku 4.5	$0.00013	$0.00191

Measured 2mo ago against content hash e75308b987a7, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

clerk-frontend-sdks 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 2mo 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.

plugins/clerk-auth-master/skills/clerk-frontend-sdks/SKILL.md · 183 lines

How it starts

The opening of the file, as written. The whole thing — 183 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Clerk Frontend SDKs

Overview

Use this skill for client-side Clerk integration across React and other frontend frameworks. The main job is choosing the correct framework SDK, wiring provider context, selecting prebuilt UI vs custom flows, handling environment-specific redirects, and avoiding the mistake of treating client auth state as server authorization.

SDK Selection

Prefer the dedicated framework SDK when one exists:

App type	Preferred package/pattern
Next.js	`@clerk/nextjs`
React app without a stronger integration	`@clerk/react`
React Router framework	Clerk React Router SDK/patterns
TanStack React Start	Clerk TanStack integration
Astro	Clerk Astro integration
Nuxt/Vue	Clerk Nuxt/Vue integration
Expo/mobile	Clerk Expo/mobile integration
Plain JavaScript/non-React	ClerkJS

Selecting the wrong SDK causes routing, SSR, hydration, and token propagation bugs. Check the package already installed before adding another package.

Provider and Environment Setup

Wire the frontend provider near the root of the app. The provider should receive a publishable key or use the framework SDK's environment-variable convention. Never pass a secret key, webhook signing secret, or Backend API credential to browser code.

Use development and production Clerk instances deliberately. Auth bugs often come from mixing a development publishable key with production domains, production redirect URLs, production Backend API secrets, or production webhooks.

Provider-level options and environment variables must align with Clerk Dashboard URLs:

Sign-in route/path.
Sign-up route/path.
After-sign-in and after-sign-up fallback/force redirects.
Allowed origins/domains.
OAuth redirect and callback settings for production providers.
Custom domain/proxy settings when used.

Prebuilt Components vs Custom Flows

Prefer Clerk prebuilt components for standard auth UX:

Sign in and sign up pages or modals.
User button and account management.
User profile and organization profile.
Organization switcher and organization list flows.
Multi-session account switching when supported by the chosen UI.

Read the full file on GitHub · 183 lines

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.

2mo ago First seen · 183 lines · 132 tokens per session scan A e75308b987a7

Subscribe to this mod's changes

clerk-frontend-sdks is a skill published in the GitHub repository JosiahSiegel/claude-plugin-marketplace (59 stars, last pushed 4mo ago), licensed MIT. It adds 132 tokens to every session and 1,905 once invoked, about $0.0005 per session on Opus 5.5. 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.

Frontend React Vue and Svelte

clerk-frontend-sdks next to 6 skills from other repositories
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clerk-frontend-sdksJosiahSiegel/claude-plugin-marketplace	Skill	59	4mo ago	MIT	A	132	Claude Code
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