Abbott's Lingo over-the-counter continuous glucose monitor (and to a lesser extent Dexcom Stelo) ships data into a vendor app that does not export to Apple Health for glucose readings. The fasting and metabolic-health Reddit community is loud about this: they bought the sensor specifically to feed their existing fasting app or Cronometer log, and now the data is trapped. Build a sidecar app that reads from the Lingo BLE stream (or screen-scrapes the vendor app) and writes glucose into Apple Health, Cronometer, MyFitnessPal, and a CSV export.
builder note
BLE-direct beats screen-scrape if you can do it. Abbott will not give you a public API; lean into the same legal frame the right-to-repair people use - this is your data from your sensor, you bought both. Don't market this to type-1 diabetics, that's a different (regulated) market - market it to the fasting and metabolic-health crowd who already know they want their numbers in Cronometer.
landscape (4 existing solutions)
Stelo solves the Apple Health half-of-the-problem; Lingo (Abbott) does not. xDrip exists for hardcore users but is overkill. The clean opportunity is a Lingo-specific (initially) sidecar with a quiet Stelo expansion: read from the BLE stream, write everywhere the user wants the data, charge $5-10 one-time. The biomarker-tracking crowd is small but high-LTV.
Stelo by Dexcom Does export to Apple Health (one of the few that does) but the in-app analytics are widely panned as 'pretty useless' compared to clarity.dexcom.com web data Lingo by Abbott Does NOT export glucose to Apple Health; only imports events. Users explicitly bought the sensor for the data and are stuck. Nutrisense Bring Your Own Sensor Closest commercial solution but it's its own subscription service, not a transparent passthrough into Apple Health and Cronometer xDrip+ / Spike Open-source diabetes community tools that do read directly from CGM hardware but are aimed at type-1 diabetics with insulin pumps and have a vertical learning cliff for the metabolic-health crowd sources (5)
cgmlingosteloapple-healthdata-portability
Garmin Connect 5.21.0.28 on iOS 26.2.1 unpaired Forerunner 965, Enduro 3, and Fenix 7 devices from their owners' phones in late January 2026. Even after the 5.21.1 fix shipped, users had to manually re-pair, and many found their Garmin Connect+ subscription paid for nothing during the outage. Build a third-party iOS sync companion (or a simple watchdog that snapshots and restores pairing state across Connect updates) so users aren't dependent on Garmin's QA cycle for the watches they paid $700-1100 for.
builder note
Don't try to clone Connect, it's too big. Win on one verb: 'restore my pairing.' If Garmin breaks again (and they will, this happened in 5.21 and again in 5.21.1) you become the app every angry runner installs that week. Newsletter the user the day a new Connect version hits.
landscape (3 existing solutions)
Garmin owns the BLE pairing handshake and there's no documented third-party sync app for iOS. The opportunity may not be a full Connect replacement (Garmin protocol is partially closed), but a 'pairing notary' that periodically exports your devices, custom data fields, and IQ apps to local storage so a botched Connect update can be rolled back. Also: Garmin Connect+ at $7/mo with a recent five-month track record of 'still not worth it' is itself a soft signal that there's pricing room for a paid third-party companion.
Garmin Connect 5.21.1 (the fix) Patches the bug going forward but anyone who already updated to 5.21.0.28 still needs to manually remove and re-pair. No restore-from-backup. No proactive snapshot. sources (5)
garminwearablesiosdata-portabilityfitness
Existing duplicate-photo apps (Apple's Clean Up, Smart Duplicate Finder, Clever Cleaner) make users tap through near-duplicates one at a time and people give up after 5-10 minutes. The opening is a cleanup app that defaults to 'I trust you, just delete the obvious junk' batch mode (blurry shots, screenshots older than 60 days, near-duplicates of the same scene where Photos already picked a 'best') and only surfaces the genuinely ambiguous cases for review. Less Marie Kondo, more dishwasher.
builder note
The differentiator is the undo bin and the rules engine ('delete all screenshots older than 90 days', 'keep one of each near-duplicate burst', 'flag faces I haven't tagged'). Apple won't ship this aggressively because their incentive is to keep your iCloud bill big. That's the opening.
landscape (3 existing solutions)
Every existing tool optimizes for precision (don't delete a photo the user wanted). The real ask is the opposite: aggressive recall with a 30-day undo bin, because users will trade a 0.1% false-delete rate for not having to think 50,000 times.
Gemini Photos / Smart Cleaner macOS-first. Same one-by-one decision UX. Doesn't address screenshots-of-receipts and dead memes that account for a third of most camera rolls. Clever Cleaner Better duplicate detection but same UX pattern. The cognitive cost is the bottleneck, not the recall. sources (1)
photosiosuxaiconsumer
Mitsubishi Electric, Daikin, Fujitsu, and Hitachi own the heat-pump market in much of the world, ship their own MELCloud/D-Mobile/etc cloud apps, and each refuses to sign on to Apple Home, leaving owners to either pay $199 per Sensibo IR-bridge per unit or rely on dealer-installed Kumo modules with limited shortcut support. The opportunity is a software-only iOS app that sits on top of MELCloud's existing API plus equivalents and exposes them as native HomeKit accessories without dedicated hardware.
builder note
Mitsubishi will not respond to your support emails. Don't ask. Build against MELCloud and the equivalent Daikin/Fujitsu cloud APIs the way the Home Assistant community already does. Charge $30 one-time per household, or $20/year for cloud relay if Apple kicks you off the local-only path. Beware: any one of these vendors could ship native HomeKit tomorrow and instantly kill the wedge for that brand. Multi-vendor coverage is the moat.
landscape (4 existing solutions)
The native cloud APIs are all already publicly accessible (the open-source Home Assistant integrations prove this). The gap is a polished consumer iOS app that does the bridging without making the user learn Home Assistant or buy hardware they don't need.
Sensibo Air Hardware IR-bridge at $149-$199 per AC unit. Wasteful for owners who already have a wired wifi module from Mitsubishi/Daikin and don't want a stick-on duplicate. MELCloud Mitsubishi's own cloud app. Functional but no HomeKit, no Shortcuts, no automations beyond a single weekly schedule. Mitsubishi Kumo Cloud US-only, requires a $300 dealer-installed module that not all units support. Apple Home support exists per official docs but users repeatedly report it not working in practice. sources (1)
homekitsmart-homehvaciosinternational
Beginner photographers keep asking the same question: what's the iPad RAW editor that isn't Lightroom and isn't a subscription. The 92-comment thread shows the depth of frustration: Darkroom went subscription, Affinity Photo 2 is heavy and not workflow-focused, Capture One iPad requires the desktop subscription. Photographers are explicitly willing to pay $50-150 once.
builder note
This is hard to build but the moat is huge if you ship it. The competitive question isn't 'can you match Lightroom features'... it's 'can you build a culling-and-cataloging UX that feels native to touch.' Lean into Apple Pencil + iPad multitasking. Charge $79 one-time with $19 yearly major-version updates... Adobe-fatigued users will pre-order this.
landscape (3 existing solutions)
Adobe owns the workflow standard. Affinity owns the one-time-purchase price point. Nobody combines workflow + one-time purchase + iPad-first. The hole is real.
Darkroom iOS-popular but moved to a subscription model that pushed away the one-time-purchase crowd. iPad-only, no Android. Affinity Photo 2 for iPad $19 one-time, but it's a Photoshop clone, not a Lightroom replacement. Workflow for cataloging and culling RAWs is poor. Capture One iPad Pro-grade, but requires the desktop subscription to unlock. Killed the standalone iPad pricing path. sources (1)
photographyipadlightroom-alternativeraw-editoranti-subscription
Developers and engineering managers want a polished iOS/Android app dedicated to code review on the go — read PR diffs cleanly on a phone, leave inline comments, approve/merge with one swipe, see a queue across all repos. GitHub Mobile and GitLab's app treat PRs as a side feature behind issues; the diff-rendering on phones is awful. April 2026 'Ask HN: What are you working on' threads show multiple devs frustrated with reviewing PRs from a phone during commute or after hours.
builder note
Ship iOS first because the audience skews staff-engineer-with-iPhone. The killer feature is 'archive after merge' inbox semantics plus a swipe-to-approve gesture. Don't try to render full repos — render just the PR-as-conversation.
landscape (3 existing solutions)
The 04-13 signal covered mobile-first IDE for developers; this is the narrower, higher-conviction wedge specifically for code review. Code-review is an inbox-shaped task — small, frequent, social — that maps perfectly to mobile UX, but neither GitHub nor GitLab has invested in making it a phone-first experience.
GitHub Mobile Issues-first UX; PR diff rendering is cramped; no inline comment workflow that survives long files; no queue across orgs. GitLab Mobile Same problems plus weaker; built as a viewer, not a doer. sources (2)
dev-toolsmobilecode-reviewgithubios