Apps you buy once.

Catch: It scans and nothing else. No annotating, no signing, no fixing a PDF somebody sent you — for that you need one of the readers below as well.

Catch: Five of the last two hundred reviews call it hard to find your way around, and others say the notifications cannot be turned off once they start.

Catch: A few users report it's gone stretches of many months without updates and started behaving unreliably, and importing historical data requires manually long-pressing every single day rather than a bulk export.

Catch: It is built around wind and brass, and guitarists say so — four of the last two hundred reviews call it unintuitive for guitar specifically, where a plain chromatic tuner would be quicker.

Catch: Six of the last two hundred reviews describe a version that stopped working for them, and others say it runs the battery down overnight. For something meant to play until morning, that matters.

Catch: Paying for Pro does not buy all of it. Reviewers report CarPlay and some radar features still behind a further subscription, and others quote a privacy policy that reserves the right to sell personal data.

Catch: Eleven of the last two hundred reviews report it crashing or shooting slowly, and a few describe it firing several frames when they wanted one. On a camera, missing the shot is the whole failure.

Catch: Reviewers describe it crashing, and it is scanning only — there is nothing here for reading or marking up the PDFs once you have them.

Catch: Fifteen of the last two hundred reviews say it stopped blocking, and five more say the app has been abandoned. Treat it as an experiment, not a fix.

Catch: Seven of the last two hundred reviews say a reminder did not fire when it should have. Unusual for something this polished, and it is the one job a to-do list cannot get wrong.

Catch: You buy it and it still asks: sixteen of the last two hundred reviews are about sound effects and extras behind a further subscription, and fifteen more describe fighting to get a finished project exported at all.

Catch: Five of the last two hundred reviews report it crashing on launch after signing in, and others describe the app pushing them toward subscription services they had not asked for.

Catch: Buying it once is not the end of it — twelve of the last two hundred reviews are from people who found a newer version waiting behind another payment, and several say the one they bought stopped being supported.

Catch: You buy it and then it asks again: fourteen of the last two hundred reviews are about a subscription sitting on top of the purchase, mostly to sync files with cloud storage.

Catch: Thirty-three of the last two hundred reviews say it is now unusable, nineteen more that importing a clip freezes it. Reviewers openly recommend free alternatives instead.

Catch: It looks its age and people say so — the interface draws as many complaints as compliments, and several reviewers say it took real effort before it clicked.

Catch: Identifying is all it does. There is no observing planner, no telescope control and nothing like the depth of catalogue the bigger apps carry — outgrow it and you are buying twice.

Catch: Twenty-seven of the last two hundred reviews report crashes, and thirteen more say Google Drive syncing stopped working. That is a lot of risk to carry a day's marking in.

Catch: It costs noticeably more than typical unit converter apps, and with no updates in years you're trusting that its unit database and iOS compatibility won't need fixing down the line.

Catch: Reviewers report severe-weather alerts arriving after the weather did. Do not make this the thing that warns you.

Catch: It will not help you identify what is above you tonight, and reviewers report parts of it sitting behind a further subscription despite the purchase.

Catch: The dearest app on this list, and reviewers report it freezing mid-session. That is a poor trade when the cheaper tuners here do the basic job just as accurately.

Catch: The Mac version does not take keyboard input, which makes it close to unusable there, and reviewers report updates breaking things that previously worked.

Catch: Three of the last two hundred reviews describe losing their entire vault, and there is no export anyone else can read, so there is no way to keep a copy elsewhere.

Catch: Notifications are the most common complaint by some distance — several reviewers say alerts simply never arrive — and support does not answer email.

Catch: Syncing is the running complaint — fifteen of the last two hundred reviews say it fails, mostly over Dropbox — and reviewers say opening a local copy now pushes you toward paid cloud storage.

Catch: Nine of the last two hundred reviews call the current version close to unusable, and backing up or exporting setlists has been broken for several iOS releases.

Catch: It only exports to its own format, so reviewers who wanted to leave found they could not take their passwords with them. A few also report losing data outright.

Catch: It is a graphing calculator and nothing else — no tape, no unit conversion, none of the everyday conveniences — and no exam hall will let you bring a phone, which is where most people actually need a TI-83.

Catch: The listing opens by telling you this is the legacy version and pointing at a newer one. Four of the last two hundred reviews say it has been left to rot.

Catch: It costs more than every other app on this list put together, several times over. Nothing in the reviews suggests it is better at putting you to sleep than the one-dollar option.

Catch: It is far and away the most expensive app on this site, and six of the last two hundred reviews call the current version unusable. That is a great deal of money to risk on a scanner.

Catch: A handful of reviewers report the app crashing on open, sometimes right after purchase, and it hasn't been updated in years so that's unlikely to get fixed.

Catch: Reviewers report audio drifting out of sync once footage is exported elsewhere, and several say emails to the developer went unanswered.

Catch: Twice the price of anything else here, and the DNS filtering it advertises keeps steering you toward AdGuard's separate paid DNS and VPN plans.

Catch: The nagging is the point and it does not suit everyone — thirteen of the last two hundred reviews are about notifications being too much or arriving wrong.

Catch: It is a single effect. Outside of long exposures there is no reason to open it, and you will still want a normal camera app for everything else.

Catch: You have to unlearn a calculator to use it, and a crash reviewers have been reporting since iOS 11 still turns up in recent reviews.

Catch: It is the paid version of a dictionary that is already free with adverts. What you are buying is the ads removed and the content stored on the device — useful, but not new words.

Catch: The most complained-about app on this list, always for the same reason: twenty-six of the last two hundred reviews say the genuinely useful extras sit behind subscription tiers on top of the purchase.

Catch: Syncing is the most common complaint by a wide margin — thirty-nine of the last two hundred reviews raise it against eighteen who say it works — and it runs through Dropbox rather than iCloud.

Catch: The most expensive here, and reviewers dispute how much of it truly works offline — a few say the offline content they paid for was not there, and others that an update made it slow.

Catch: Five of the last two hundred reviews say it has gone years without an update, and four more say support has moved on. For a password manager that is the thing to weigh, not a footnote.

Catch: Syncing runs through your own Dropbox or Google Drive rather than iCloud, so the vault sits in a third place you also have to keep secure — and the recent review record is thin enough that there is less evidence here than for the others.

Catch: Sixteen of the last two hundred reviews describe syncing destroying their decks, ten call it overpriced and nine call the interface baffling. It is the dearest app here by five times and the lowest rated.

Catch: Reviewers note you can't use the sounds as morning alarms, and with no updates in years, don't expect that or any other new feature to ever show up.

Catch: Downloading the maps in the first place is slow, importing a GPX route often fails outright, and reviewers say the route planner has started freezing.

Catch: Multiple reviewers report the app crashing specifically during scanning, saving, or exporting documents, and it does not work reliably with iCloud files — a serious problem if you need to get a signed or annotated PDF out to someone else.

Catch: More recent reviews say the offline maps stopped working than say they work — twenty-four against twenty — and four more say nobody answered when they wrote in about it.

Catch: Continental United States only, it can be slow to load on a connection that is not, and reviewers who emailed support did not get an answer.

Catch: Steady on iCloud and shaky off it. Reviewers working out of Dropbox or Google Drive report freezing and lockups, and that is where most of the crash reports come from.

Catch: No metronome, no recording, no history — if you need more than pitch you will end up buying a second app, which costs more than buying one of the combined ones outright.

Catch: It is a tracker with a map, not a navigator — there is no routing and no turn-by-turn, so it will show you where you are and leave the rest to you.

Catch: There is a learning curve and reviewers say so — and unlike the top pick it is stills only, so anyone who also shoots video needs something else.

Catch: Blocking inside other apps is a separate add-on bought on top of the app, and reviewers who had already paid were unhappy to find a second price behind it.

Catch: Syncing is almost evenly split in the reviews — thirty-two say it works, twenty-seven say it does not — and five more say support did not reply when it broke.

Catch: The review evidence barely touches on sound variety or customization, and with no updates in years, any new iOS audio features or bug fixes simply won't come. Buyers are trusting a frozen app based mostly on praise for its look and feel.

Catch: No spaced repetition. It shows you cards, you say whether you knew them, and that is the extent of the intelligence — fine for cramming, weak for learning something over months.

Catch: Barely ninety recent reviews, and the only recurring theme in them is that it misses ads. There is not enough evidence here to be confident either way, so buy it last.

Catch: Multiple reviewers report notification and alert settings not working as expected, and a few describe the app crashing on launch — risky for anyone counting on it for storm warnings.

Catch: By far the most expensive map here, and nine of the last two hundred reviews say tracking has drifted badly or stopped working altogether. That is a lot to pay for something reviewers say failed them.

Catch: Getting cards in is the weak point — there is no CSV import, and reviewers who bought the Windows companion found decks would not move between the two.

Catch: The interface is not obvious and reviewers say so, and a few report it freezing partway through rendering, which wastes the whole export.

Catch: Nine of the last two hundred reviews call it unusable outright, and others say a small edit takes an age. At this price that is the gamble.

Catch: Nine of the last two hundred reviews say a recent update made it hang on certain notes, which is a bad failure for the one thing it does.

Catch: The dearest app here and the least steady with it: thirty-one of the last two hundred reviews report crashes or hangs, and several say support never replied.

Catch: Some users on newer iPhones report the app crashing frequently, and its sky-position tracking has been reported as inaccurate, both issues unlikely to ever be patched given the app's age.

Catch: Multiple reviews describe crashes that corrupt or lose in-progress files, especially when importing photos or running low on memory, and this is called the legacy version so there's no indication it will be fixed.

Catch: It is lists, not tasks, so there is no real scheduling here. Four of the last two hundred reviews also report it crashing.

Catch: The interface has not been rethought in years — reviewers call the navigation unintuitive and long nested documents awkward — and Dropbox is where the sync complaints cluster.

Catch: It looks and behaves its age. Six of the last two hundred reviews call it unusable, describing results dumped into one window of tiny text with no way through them.

Catch: The interface is genuinely confusing and six of the last two hundred reviews say so, and CSV files do not always come in cleanly despite import being the main reason to pick it.

Catch: Syncing is where it falls down — nineteen of the last two hundred reviews describe it hanging on download or crashing when opening a file it did not create itself.