Explore nearby Bluetooth signals, local network services, and magnetic-field changes—all on your device.
iPhone · iOS 27 or later
Meet Spectra
Three ways to explore the space around you.
See nearby Bluetooth broadcasts, discover supported services on your joined Wi-Fi network, and explore close-range magnetic clues. Spectra brings the results together, with the evidence behind each observation.
Explore possible device identities and camera, audio, smart-glasses, or wearable indicators without pairing with or connecting to discovered devices.
Signals are clues, not proof that a device is hidden, recording, or malicious. A quiet scan cannot guarantee that a space is clear.
For unfamiliar places
Privacy matters wherever you go. Start with what you can observe, then decide whether a closer look is worthwhile—not whether an app has declared a place safe.
Get oriented at a hotel or Airbnb with a Quick Check. Use Area Sweep to explore accessible areas you are allowed to inspect at your own pace. A repeatable magnetic change is a reason to look more closely, not proof of a hidden camera.
In student housing, gyms, and changing rooms, privacy boundaries matter. Observe available broadcasts without pairing, follow facility rules, and review findings away from others. Do not photograph people, dismantle fixtures, or treat an unfamiliar signal as wrongdoing.
As a rideshare passenger or while waiting in an airport, station, or café, take a quick radio snapshot or check for recognizable glasses and wearables. Crowded spaces contain many ordinary devices. A match cannot identify their owner or tell whether they are recording.
Signals can come from outside the room; silent devices may not appear at all. If you have a credible concern, leave sensitive activity for a more appropriate location and contact a trusted safety or security resource. Do not confront someone based on a scan.
Read the practical travel guideInside the app
Explore real screens from Spectra. Readings are simulated examples, not evidence of nearby devices. Select a screen to view it full-size.
Start a quick radio check, explore with Area Sweep, or monitor the area.
Smart Glasses and Watches & Wearables have dedicated checks. See possible matches clearly, with their evidence and limits.
Repeatable, close-range magnetic changes may guide a closer physical look—not identify a device. Magnetic measurement is available in Area Sweep; Quick Check focuses on radio signals.
Keep the phone still and Spectra open. Review an activity snapshot without stopping; Stop Monitor opens the full retained inventory. Shown in the 1.1.0 release candidate.
Experimental Watch · Included with Spectra
Capture without your iPhone nearby. Take an intentional, 30-second Bluetooth Area Sweep from your wrist and save up to five captures on Watch. Keep Spectra active and the display fully awake. Reconnect and open Spectra on your paired iPhone to identify signals and review findings in Sessions.
When a newly received result is saved, a quiet Watch sweep added cue offers View on iPhone. Nothing opens automatically and no notification is sent. Your session keeps its original capture date, even when it arrives later.
Bluetooth only—not background scanning, magnetic measurement, or local-network discovery. An interruption keeps a partial capture. Unsent captures are kept; full storage can block another sweep. Delivery may wait for connectivity or Apple’s scheduling.
Optional companion · watchOS 27 or later · Paired iPhone with iOS 27 or later and Spectra required. The iPhone app works without a Watch. The Experimental companion is included with Spectra.
Read the Experimental Watch guide
Start deliberately. Keep the app active until it finishes.
View full-size screen
Saving, delivery, and identification are separate steps.
View full-size screenActual app screens · Example data, not nearby-device evidence.
A check for every setting
01 / Quick Check
Take a roughly 30-second look at nearby Bluetooth broadcasts, with optional local-network observations. No magnetic measurement or calibration is needed.
02 / Area Sweep
Move through the area, compare Bluetooth signals, and optionally follow the live magnetic meter. Finish when you’re ready. A quiet notice after 25 minutes lets you extend the 30-minute limit; otherwise, Spectra finishes the sweep using your saving preference.
03 / Monitor This Area
Keep the phone stationary. Each selected, available radio observes for 30 seconds to establish a baseline; you can extend this once to 60 seconds. In the 1.1.0 release candidate, New identities recorded excludes identities seen earlier in this Monitor session, and View activity & help opens a fixed snapshot while measurement continues. Choose New Baseline for a fresh comparison; Stop Monitor opens the full retained inventory. Foreground monitoring only—not an unattended alarm.
How it works
Quick Check listens to Bluetooth and optional local-network services. Choose Area Sweep for hands-on exploration with the live magnetic meter.
Recognize available broadcasts. After a check, choose a found Bluetooth identity from grouped results and open Bluetooth Proximity for its live signal-strength reading. Less-negative dBm means stronger reception: −45 dBm is stronger than −75 dBm.
Signal strength—not an exact distance or direction.
Find advertised services on the Wi-Fi network you’ve joined, from speakers and streaming receivers to smart-home products.
Network presence—not a scan of every nearby Wi-Fi radio.
Look for clues to concealed electronics. Some electronic components produce magnetic fields that your iPhone’s magnetometer may detect at close range—even without a recognizable wireless broadcast. During a careful physical inspection, use repeatable changes to decide where to take a closer look.
A change cannot identify a camera or microphone or prove recording. Ordinary magnets, magnetic metal, chargers and phone accessories can also affect readings. Some devices produce little detectable change; a quiet reading does not rule one out.
Available in Area Sweep. See actual field readings, then compare changes from a stable reference. A higher actual µT value means a stronger field; a larger positive or negative delta means a bigger change from the reference, not a distance. Quality-gated spike detection uses its own calibrated baseline. Revisit the saved, downsampled graph after the check.
Position matters: the magnetometer measures at one small point, not across the whole phone. Its location varies by model. Keep the angle and gap consistent as you move slowly. Learn how to use magnetic measurements, including where to aim your iPhone.
Explore possible devices, product families, and supported network-service roles from reviewed on-device knowledge. A service can remain useful when the device type is undetermined, without proving physical hardware or an exact model. After finishing, narrow results by recorded measurement or search displayed and broadcast names. These controls do not change saved evidence or exports.
Choose one finding for an optional Apple Intelligence explanation on your iPhone. Generated text is temporary and excluded from exports.
Or choose Use Another App. Spectra places a ready-to-use prompt before the selected finding’s evidence, asking an external AI to explain what it may be, assess uncertainty, and suggest useful next steps. Review the exact text, then choose Share or Copy on the same screen. Share opens Apple’s share sheet; Copy puts the text on the clipboard to paste into your preferred app.
Nothing uploads automatically; the recipient handles shared text under its own policies. Available destinations depend on the receiving app. AI can make mistakes.
Start a dedicated 30-second Bluetooth check for Smart Glasses or Watches & Wearables. Review supported matches and their evidence, with other observed Bluetooth activity available separately. That context is not counted or exported as a specialist match. A match cannot establish listening or recording, and some devices may not broadcast recognizable signals.
When an app update brings newer recognition, recheck eligible saved radio evidence on your iPhone—even after leaving the location. A blue dot in Sessions points the way. Save a separate numbered interpretation while keeping the original unchanged. No new signals are collected, and better matches are not guaranteed.
Remember where you started: optionally turn on Tag location before an iPhone check. It saves one approximate position, not a route or a detected device’s location. Enable automatic map previews once to see saved areas through Apple Maps whenever you view tagged results. Or choose Not now; your choice is remembered and can be changed in Settings, under Session maps. Tags stay out of exports by default and are always excluded from on-device finding analysis and external finding shares or copies.
Find saved checks in expandable day groups. Add names and notes, replay magnetic graphs, or export JSON. In Session Storage, choose Export All Sessions to save one Spectra ZIP collection. Use Import Sessions to restore a supported Technical archive or Spectra ZIP after review—no unzipping needed.
A collection adds all new sessions together or none; already-saved copies stay unchanged, and conflicts or invalid files block the import. Imported records are historical, not fresh or authenticated measurements; importing starts no scan, analysis, or map.
Saved sessions are not automatically removed. Track the independent 500-session and 256 MiB history limits, then delete copies you no longer need to make room. Turn automatic iPhone saving off or reset the app when you choose. Explore saved sessions, import, and rechecks.
The Arc Signal approach
On your device. Under your control.
Investigate electronic clues without handing your observations to a server. Apple Intelligence can explain one selected finding locally using a compact summary. Generated explanations are clearly labeled, temporary, and excluded from exports; they are an aid to review, not proof of safety or surveillance.
No website analytics, forms, or tracking pixels. Fonts and images load locally; our hosting provider may retain routine request logs. Optional referral links are explained in our website privacy details.
Read the Spectra privacy policyGood questions
Spectra requires an iPhone running iOS 27 or later. The optional Experimental Watch companion requires watchOS 27 or later and a paired supported iPhone; the iPhone app works without an Apple Watch. Scanning and exports do not require Apple Intelligence. Only optional on-device analysis needs compatible hardware and enabled, available Apple Intelligence. Each measurement depends on its hardware and permission.
No. Spectra reveals available signals, not a safety verdict. Silent, powered-off, wired, shielded, cellular-only, or locally recording devices may not appear. Use findings as a reason to look more closely.
No pairing or direct connection is needed. Local-network discovery requires joining the network and granting permission. Results depend on your chosen sources and device capabilities.
No. Names and metadata can be changed or spoofed. Matches are possible or probable identities, with the underlying observations available for review.
No. Counts describe signal identities, not physical devices. Categories such as Watches & wearables depend on supported matches; other signals may remain unclassified. One device can broadcast several identities. iPhone scans use the same recognition rules for live counts and completed results. Finishing organizes the retained evidence; it does not run a stronger scan. Understand live counts and recognition limits.
The magnetometer measures at one small sensor, whose position varies by iPhone model. For iPhone 17 Pro Max, Apple’s drawing places the compass near the lower back at the USB-C end—not the camera area. Spacing, orientation, shielding, and magnetic accessories affect the response, and some devices produce little detectable change. No change does not rule out a device.
Before exploring an unfamiliar space, choose Practice with the magnetometer in the app’s magnetic Guide or sweep preparation. It uses live magnetic readings only, without radio scanning or saving a session. Compare an ordinary speaker you own with a spot away from electronics. Keep a gap and repeat the same slow pass; do not press magnets against the phone. This is familiarization, not calibration or a pass/fail sensor test. Stop Practice, Done, or leaving the app clears practice readings. Start a separate Area Sweep and fresh reference for the space you intend to review. Read the practice and positioning tips or see Apple’s model-specific compass drawing (PDF, page 5).
Spectra includes an optional Experimental Watch collector: one intentional, 30-second Bluetooth Area Sweep. New captures save on Watch and automatically queue for your paired iPhone. Open Spectra on iPhone to identify the signals and add the result to Sessions. It is not a background scanner. Set the Watch’s Wake Duration to 70 seconds, tap to wake fully, and keep Spectra active; Always On alone is not enough. An interruption keeps a partial capture instead of claiming a full scan.
In Sessions, a Watch-with-radio-waves icon and Apple Watch · Bluetooth-only sweep label identify where the capture came from, even after renaming or rechecking. This is a general Bluetooth sweep collected on your Watch, not a search specifically for nearby watches. Experimental and partial-capture status remain visible.
On Watch, Settings holds sweep guidance, storage and transfer information, diagnostic reports, installed version details, and the optional completion haptic. The start screen stays focused on starting a sweep; the tray opens Saved sweeps.
Transfers may wait for connectivity or Apple’s scheduling. Settings → Experimental Watch on iPhone provides status and retry controls. The Watch does not scan local networks, measure magnetic fields, or run specialist modes. Experimental behavior continues to be evaluated across Watch models and environments. Review capture coverage and transfer status rather than assuming a complete sweep. Read setup, transfer, and privacy details.
Yes. After installing the Experimental Watch companion and opening Spectra on your paired iPhone once to prepare transfer, you can leave the phone behind. The Watch uses its own Bluetooth radio and saves locally; collection needs no internet connection or cellular plan. Bluetooth access and a fully awake, active Spectra screen are still required.
Check Saved sweeps before leaving: the Watch holds up to five captures in total, including earlier copies. Unsent captures are not automatically overwritten. Only safely received copies can make room automatically; if none can be replaced, free storage before another sweep. Reconnect and open Spectra on your paired iPhone to identify signals and review findings. The Watch shows capture status, not identified results. Read the Watch Guide.
Use Search sessions at the bottom of Sessions to find saved names, notes, check types, and sources. Filters narrow by type, collector, or Imported status—not device names or raw payloads inside captures. Search Guide searches help separately. With automatic iPhone saving off, Save Session keeps one completed check without changing your preference.
Open Storage → Session Storage → Largest Sessions to compare estimated sizes. Every saved copy, including rechecks and imports, appears independently. Deleting there requires confirmation and has no Undo; estimated size may differ from reclaimed space. In the main Sessions list, choose Select and use Export to review a ZIP containing only your selected copies. Search and filters stay fixed while selecting; an original does not include rechecks automatically. Location tags remain excluded by default. Exporting does not remove history, and Import Sessions can restore a supported Spectra ZIP after review.
Erase All Sessions is in Session Storage and includes all saved history regardless of search or filters. Saved sessions are never removed automatically. For an optional short touch when an iPhone check ends, enable Completion haptic in Settings → Preferences. It is off by default; feedback does not confirm saving, complete coverage, or a safe area. Read the saved-session Guide.
Yes. Tag location is an optional choice before each iPhone check and starts off every time. With your permission, Spectra tries to save one position near the start, together with its accuracy and fix time. Scanning still works if location is unavailable or you decline access. No route, background location history, or street address is collected. Watch captures stay untagged.
Review the saved coordinates and accuracy in the session. The first tagged result offers Enable map previews or Not now. Enabling allows automatic Apple Maps previews of saved areas without requesting your current position. Declining is remembered without repeated prompts. Change Automatic map previews in Settings, under Session maps. Its marker and shaded area describe the collecting iPhone and estimated accuracy—not detected devices or a verified venue. Open in Maps is a separate choice. If a preview cannot load, the coordinates and findings remain available.
Remove location removes the tag from that session copy only. All JSON formats omit it by default. Include scan location adds it to a single-session export when you explicitly choose; a collection uses Include scan locations. On-device finding analysis and external finding shares or copies never include the tag. Learn about location tags and saved copies.
Yes. We regularly improve Spectra’s device catalog and detection engine to help you make better sense of nearby signals. These improvements are included in App Store updates at no additional charge—no separate catalog purchase or subscription.
Install the latest app update to use newer recognition. It can also help you revisit eligible saved sessions with Recheck session, preserving the original. Updates do not guarantee a match or make every device detectable. Learn about saved-session rechecks.
Recheck session appears only when newer compatible recognition is available and the session retains enough usable radio evidence. A fresh capture already using the installed recognition normally needs no recheck. Some older or incomplete captures cannot be reassessed. Catalog updates arrive with app releases—not separate downloads. Rechecking needs no Apple Intelligence and cannot recover missing measurements or tell you what is at that location now. See eligibility, naming, and storage details.
Reset Spectra on iPhone clears local sessions and settings, then requests erasure of captures, diagnostics, and settings in the known paired Watch app. An offline Watch may retain data until it receives and completes that request. Review Watch reset pending or Watch reset confirmed in Spectra’s iPhone Settings. Erase All Sessions, in Session Storage, clears iPhone history and received inbox captures only; it does not request a Watch reset. Files already exported elsewhere remain. Read reset and recovery guidance.
Now available on the App Store
Explore the signals around you with Spectra for iPhone. Your purchase includes the Experimental Apple Watch companion.
U.S. price: $2.99
One-time purchase. No subscription.
Ongoing device catalog and detection-engine improvements are included in app updates at no additional charge.
Prices in other regions may vary. Check the App Store for your local price.
Requires an iPhone running iOS 27 or later. Scanning does not require Apple Intelligence. Optional on-device analysis requires an Apple Intelligence-capable iPhone with the model enabled and ready in a supported language and region.
No in-app purchases. Choose measurements, grant access, and start scanning.
Beyond the scan
Spectra observes nearby electronic clues. Protecting your accounts, connections, and conversations is a separate part of staying informed.
Confirm the intended Wi-Fi name with the venue through a trusted channel. A familiar name is not authentication. Prefer cellular data if you do not trust the network; do not join unfamiliar Wi-Fi just to improve a scan. HTTPS protects traffic to a site, not the trustworthiness of the site itself.
A trusted VPN can protect traffic routed through its encrypted tunnel on shared Wi-Fi; trust shifts to the VPN provider. HTTPS already protects much web traffic. A VPN does not stop nearby recording, authenticate a hotspot, guarantee anonymity, or make malicious sites safe.
Keep iOS and apps updated, use unique passwords and multifactor authentication, and heed certificate warnings. Protect sensitive screens and conversations. Follow your organization’s security policy; do not disable a required VPN to improve local-network discovery. Bluetooth and magnetic checks do not need that network.
Affiliate partner
Spectra helps you understand nearby signals. NordVPN complements that awareness by encrypting internet traffic routed through its VPN connection—a useful option to consider on shared Wi-Fi at hotels, cafés, and airports.
NordVPN is a separate paid service, not included with Spectra and not required to use it. Check current plans, supported features, pricing, and renewal terms on NordVPN’s website.
Arc Signal may earn a commission if you purchase through this link.
Explore NordVPN plansA VPN protects routed network traffic, not your physical surroundings. It cannot detect or prevent nearby recording. About this link and your privacy.
NordVPN and the NordVPN logo are trademarks of Nord Security.
Independent guidance
A VPN is optional, not a substitute for everyday security habits. Spectra does not provide one. Local-network discovery may be limited by VPN settings; that is a coverage limitation, not a reason to weaken required protection.
Independent development
Enjoying Spectra? Support the work behind it.
An optional contribution is a way to show your appreciation for Spectra and support device research, real-world testing, and thoughtful improvements.
Your purchase already supports our work. App updates are included—no additional payment is required.
Optional one-time contribution · Checkout hosted by Stripe.
