Nuxt runtimeConfig: which keys are public by design
Nuxt streams server data into the page as window.__NUXT__; values read in the wrong context ride along. Free deployed-app scan.
Nuxt splits configuration honestly — public versus private contexts — and then trusts you to respect the split at read sites. Composables used client-side blur it.
Context rules, streamed payloads, and the misuse patterns we find.
The mechanism, precisely
runtimeConfig declares two families; Nitro serializes whatever reaches client rendering into window.__NUXT__:
- private-context values stay server-side when accessed in server contexts.
- Accessing them from client-executed composables pulls them into serialization.
- window.__NUXT__ ships the resolved values verbatim.
- KeyDrift reads those payloads as carefully as chunks — capability noted, not boasted.
export default defineNuxtConfig({ runtimeConfig: { apiSecret: "" } });
// later, in a composable used client-side:
const { apiSecret } = useRuntimeConfig();// server-only plugin/route uses private context;
// client calls /api/proxy.Substitution is static and total: the literal replaces the reference everywhere the prefixed name appears, in every chunk, before anything is minified. Obfuscation changes what the string looks like; it does not change who can read it.
Variations of this mistake
- Whole config objects returned from server helpers to client callers.
- Public/private duplication drifting apart over refactors.
Where the value belongs instead
The working pattern keeps the call on a context that holds secrets without serving them, and gives the browser an endpoint to ask instead.
Verify what your build actually ships
Search the deployed JavaScript for __NUXT__ in DevTools — thirty seconds, no tools beyond the browser. What you find is ground truth; everything earlier in the pipeline is intent.
The faster path is to let a machine do the fetching. KeyDrift downloads the same JavaScript a visitor gets — HTML, every referenced chunk including ones named only in the route manifest, and the server-streamed data frameworks inline into the document — and reports credentials with a masked prefix, a fingerprint, and the exact file they live in. Paste your deployed URL into the scanner; no account needed.
Why snapshots are not enough
It bears saying because it happens constantly: the fix holds until the next prompt that needs the query to return rows. Drift monitoring exists for precisely this — it diffs consecutive scans and pages you when a previously resolved finding reappears, naming the regression as a regression rather than repeating the first alert.
Why this failure class persists
Zoom out and the pattern is bigger than one repo. AI-assisted output has outgrown review capacity everywhere at once, which means thousands of teams are making the same reasonable-looking tradeoffs in the same week. Nobody using modern tooling is uniquely exposed. The failure mode documented above is the modal outcome of velocity without verification, not evidence of carelessness.
How KeyDrift reports this exact finding
Report anatomy matters during incidents, so it is worth reading once calmly: masked string (never the live value — it ceases to exist outside the detection engine), salted fingerprint (trackable within your workspace, useless to strangers), chunk path (your starting point for a "git log -S" hunt), disposition (secret versus public-by-design), confidence (matches below 0.5 never reach the page at all).
Manual check, step by step
The full manual drill, for readers who want zero dependence on any tool: open the deployed site in a private window; launch DevTools → Sources; use Search-all-files (Ctrl/Cmd+Shift+F) for __NUXT__; then repeat for the other marker families — eyJ, sk_live_, sk-proj-, AKIA, postgres, BEGIN PRIVATE KEY. Decode anything JWT-shaped before reacting, and classify public-by-design formats as expected guests rather than intruders.
Close the loop with monitoring
If you take one operational step from this page, make it this: put the URL under continuous monitoring (free tier covers one project daily). The first scan tells you whether you have a problem today; the schedule tells you whether the problem comes back next month after someone re-adds the convenient line.
What the plans change
- Free $0 — 1 project · daily scans · email alerts · findings always visible.
- Indie $29/mo — 3 projects · hourly · Slack added · 80 chunks per scan.
- Team $89/mo — 15 projects · every 15 minutes · Discord + webhooks · 150 chunks.
- Growth — from $249/mo, quoted display-only until checkout ships.
The constant across every tier: plans limit how much is watched, never what a scan found. Visibility is structural, not promotional — asserted by tests over the entitlements model itself.
Common questions
useRuntimeConfig in components always bad?
For private keys, yes — components hydrate client-side. Public keys are fine anywhere.
Payload extraction disabled?
Disabling payload transport changes performance and some features; the safer habit is context discipline.
Run a free scan at keydrift.dev/scan — paste a URL or the bundle source itself, no account. Findings arrive masked, with the exact chunk they live in.