Guidance for storing API keys and other secret values safely in applications. It explains which environment variables can stay on a server, which values may be exposed to browsers, and how to replace leaked keys.

Use it when setting up environment variables, fixing an exposed key, choosing safe settings for frameworks such as Next.js or Vite, or rotating compromised secrets.

It reduces the risk of committing passwords or private keys to source control or accidentally sending them to users in frontend code.

secure-keys — Skill for Claude Code by Wishmakingfairy

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 Wishmakingfairy/vibecheck --skill secure-keys

Clone the repo

git clone --depth 1 https://github.com/Wishmakingfairy/vibecheck

Made for: Claude Code.

Or install vibecheck, the plugin that ships this one along with the rest of its 4 skills, 1 agent, 1 hook.

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/wishmakingfairy/vibecheck/secure-keys/github.svg)](https://agentmods.dev/skills/wishmakingfairy/vibecheck/secure-keys)

Your own site

<a href="https://agentmods.dev/skills/wishmakingfairy/vibecheck/secure-keys"><img src="https://agentmods.dev/badge/skills/wishmakingfairy/vibecheck/secure-keys/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/wishmakingfairy/vibecheck/secure-keys"><img src="https://agentmods.dev/badge/skills/wishmakingfairy/vibecheck/secure-keys.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 447 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	$0.00050	$0.00447
Opus 5	$0.00025	$0.00224
Sonnet 5	$0.00010	$0.00089
Haiku 4.5	$0.00005	$0.00045

Measured 8d ago against content hash 81c35f9a74be, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

secure-keys 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 8d 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.

skills/secure-keys/SKILL.md · 58 lines

What it actually says

Secure Keys: API Key & Secret Management

The Rule

Never put secrets in code. Never put secrets in frontend bundles. Never commit secrets to git.

Framework-Specific Patterns

Next.js

Server-only: process.env.SECRET_KEY (no prefix, only accessible in API routes / getServerSideProps)
Client-safe: NEXT_PUBLIC_ prefix (embedded in bundle, visible to everyone)
Never: NEXT_PUBLIC_SECRET_KEY, NEXT_PUBLIC_DATABASE_URL

Vite

Server-only: Not accessible in client code by default
Client-safe: VITE_ prefix (embedded in bundle)
Never: VITE_SECRET_KEY, VITE_DB_PASSWORD

Express / Node.js

Use dotenv: require('dotenv').config() then process.env.KEY
Production: Set env vars in hosting platform (Vercel, Railway, Render)

Supabase

Frontend OK: SUPABASE_ANON_KEY (public, limited by RLS)
Server ONLY: SUPABASE_SERVICE_ROLE_KEY (bypasses ALL RLS)

Secret Rotation Checklist

Generate new secret on the provider dashboard
Update environment variables in production
Deploy with new secret
Revoke old secret
If committed to git: consider the secret permanently compromised

.gitignore Template

.env
.env.local
.env.production
.env.*.local
*.pem
*.key
*-credentials.json
service-account.json

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.

8d ago First seen · 58 lines · 50 tokens per session scan A 81c35f9a74be

Subscribe to this mod's changes

secure-keys is a skill published in the GitHub repository Wishmakingfairy/vibecheck (4 stars, last pushed 5mo ago), licensed MIT. It adds 50 tokens to every session and 447 once invoked, about $0.0003 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 2026-08-31.

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