# Wallrap — Knock-test stud finder

> Knock-test stud finder (iPhone/iPad app by Robert Corbin.)

- Source: https://appshunter.io/ios/app/wallrap/id6777078648 (this page in markdown: same URL + `.md`)
- Developer: [Robert Corbin](https://appshunter.io/developer/1890247992)
- Category: Utilities, Lifestyle
- Price: $2.99
- Age rating: 4+
- Requires: iOS 17.0 · 4 MB
- Languages: American English
- Released: 2026-06-12
- Data updated: 2026-08-16
- User reviews in markdown: https://appshunter.io/ios/app/wallrap/id6777078648/reviews.md

## What is Wallrap?

Wallrap is an acoustic stud-finding aid for DIY wall checks. Rap the wall, let your iPhone listen to the pitch and decay of each knock, and see HOLLOW, EDGE, or SOLID with a confidence ring.

Wallrap includes live listening, tap-and-trace wall maps, Edge-Lock center guidance, spacing estimates for common framing patterns, saved history, CSV export, and Mount Check reports for practical verification before hanging or drilling.

All processing is local. Audio is processed live and discarded. Wallrap has no accounts, ads, analytics, tracking, subscriptions, cloud processing, or unnecessary permissions.

Wallrap is an estimate, not a precision instrument. Always confirm with an appropriate pilot hole, hardware stud finder, or professional guidance before drilling, mounting heavy objects, or working near outlets, switches, plumbing, or unknown wall cavities.

## Chart rankings

- #162 in Top Paid · Utilities (US App Store)


## Version history (last 4 releases)

### 1.3 — 2026-06-29

Wallrap 1.3 adds Mount Check for saved trace sessions. Open a saved wall trace to see the strongest candidate anchor point, a confidence score, spacing evidence, practical verification steps, and clear warnings before drilling or hanging heavy objects.

This update also refreshes App Store screenshots, support copy, and review notes so the product page matches the current app.

### 1.2 — 2026-06-26

HEADLINE — Edge-Lock live stud-center finder. New Wallrap/Models/EdgeLock.swift: pure value type EdgeLockTracker (unit-testable, KnockRun/StudPredictor pattern) holding an ordered buffer of recent (index, Classification) knocks. Exposes enum CenterState { searching, approaching(side:solidRun:), edgeCrossed(EdgeKind), centered(confidence:) } computed from the trailing run: it finds the most recent contiguous high-confidence solid run, requires a flank (hollow/edge) immediately before AND after it (the leading hollow-to-solid and trailing solid-to-hollow edges), and takes the argmax-confidence s

### 1.1 — 2026-06-16

Wallrap 1.1

Snap-to-Stud gauge (Listen mode)
The classification chip now accumulates the last 3–5 knocks in a rolling window. When they all agree with high confidence, a "STUD FOUND" or "CAVITY CONFIRMED" banner replaces the idle prompt — far more decisive than reading individual flickers. A row of colored dots shows the chronological knock sequence so you can see exactly how the window built up.

Stud spacing predictor (Trace mode)
After a trace, Wallrap now analyses the pattern of solid-segment gaps to infer whether your wall is framed 16" on-center (the US residential standard per IRC R602.3) or 24" on-center. A confidence bar and one-line summary appear beneath the map strip. The predictor is honest about uncertainty — it shows "?" when the data isn't clear enough.

Session history + CSV export
Completed traces can now be saved with an optional room note. The History tab shows every saved session with its wall map, knock counts, and spacing estimate. Tap any session to export the full knock-by-knock data as a CSV file (timestamp, centroid, band energies, label, confidence) via the iOS share sheet — useful for comparing walls or logging a project over time.

All data stays on your device. No accounts, no network, no subscriptions.

### 1.0 — 2026-06-12

No release notes.

## More apps by Robert Corbin

- [Daily Word Journey](https://appshunter.io/ios/app/daily-word-journey/id6761548266)
- [Hush Secret Text](https://appshunter.io/ios/app/hush-secret-text/id6761658175)
- [Renew Guard](https://appshunter.io/ios/app/renew-guard/id6761755447)
- [Receipt to PDF](https://appshunter.io/ios/app/receipt-to-pdf/id6761782025)
- [Route Your Pay](https://appshunter.io/ios/app/route-your-pay/id6761783719)
- [Tip Arbiter](https://appshunter.io/ios/app/tip-arbiter/id6761786879)

All apps by Robert Corbin: https://appshunter.io/developer/1890247992

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-16.*