The short version: Most "offline" Sudoku and crossword apps on the Play Store still want a connection for ads, daily puzzle syncing, or saving your progress, so you need to check settings and test in airplane mode before you trust one on a flight or in a signal dead zone. A handful store puzzles locally and work with zero data, and I'll name them, along with the exact settings that stop them phoning home.
Why "free" doesn't mean "offline"
Here's the bit most app round-ups skip. A free app and an offline app are not the same thing. Plenty of free Sudoku apps on Android are free because they're stuffed with ads, and those ads need an internet connection to load. Turn the wifi off and the puzzle screen itself still opens fine, but you get a grey box where the banner ad should be, sometimes a frozen loading spinner that eats battery while it keeps trying to fetch something that isn't coming.
Crossword apps have a worse version of this problem. A lot of them don't ship puzzles with the app at all. They download a fresh grid every day from a server, which means the app works brilliantly on your home wifi and does absolutely nothing on the Tube, on a plane, or in the countryside where your carrier has one bar and no data. If you've ever opened a crossword app at 30,000 feet and watched it sit on a spinning wheel, that's the reason.
A worked example
Say you download a crossword app the night before a long-haul flight, thinking you've sorted your in-flight entertainment for free. You open it at the gate, it loads a puzzle, looks perfect. Two hours into the flight you finish that puzzle and tap "next", and nothing happens, because the app only ever downloads one puzzle at a time and needs a connection to fetch the next one. You've got nine hours left and one finished crossword. The fix is boring but it works: before you fly, open the app on wifi and manually load five or six puzzles in a row so they're cached locally, then switch to airplane mode and confirm they still open before you leave the house.
Apps that work offline
I've covered the full tested list, including exactly which ones I turned the wifi off for and what broke, in this deeper breakdown of free offline Sudoku and crossword apps, but here's the short version for Android specifically.
- Sudoku.com stores a large batch of puzzles locally on install and lets you play through dozens with the data turned off. Ads still show when you're online, but the core puzzle grid doesn't need a connection once it's downloaded.
- Simple Sudoku and similar lightweight, ad-light apps generate puzzles on the device itself using a local algorithm rather than pulling them from a server, which means there's no daily download to fail.
- Puzzle Page (crosswords and other word puzzles) caches a set of puzzles ahead of time if you open it on wifi first, which is the same trick as the flight example above.
- AI Crossword and other apps that advertise "unlimited offline puzzles" are worth a second look at the Play Store description. If it says "sync required" or "daily puzzle" anywhere in the listing, assume it needs data unless proven otherwise.
The step-by-step before you trust any app offline
- Install the app and open it once on wifi so it can do its first download.
- Go into Android settings, find the app, and check "Mobile data and wifi" to see if it's been using data at all; zero usage is a good early sign.
- Turn on airplane mode manually (not just wifi off, because some apps fall back to mobile data).
- Open the app and try to load at least five separate puzzles, not just the one already on screen.
- Close the app fully and reopen it in airplane mode to check your progress saved locally rather than needing a server round-trip.
Do that five-minute test once and you'll know for certain, rather than hoping, whether an app will survive a flight, a tunnel, or a week in an area with patchy coverage.
The uncomfortable bit nobody mentions
Ratings on the Play Store don't tell you any of this. An app can sit at 4.6 stars with 200,000 reviews and still be completely useless offline, because most people rating it never tried it with the wifi off in the first place. Star ratings measure whether people enjoyed the puzzles, not whether the thing works without a signal. If offline reliability matters to you, which it does if you're using this on a commute through tunnels or on a plane, you have to test it yourself using the steps above. No amount of reading reviews replaces five minutes in airplane mode.
It's also worth saying plainly that some of the biggest, most polished crossword apps from major newspapers deliberately lock puzzles behind a daily download, because keeping you connected means more ad impressions and more subscription upsells shown to you. That's not a bug, it's the business model. If offline use matters more to you than having the exact newspaper crossword brand name on screen, a generic local-generation app will serve you better every time.
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What to do if nothing works offline
If every app you've tried fails the airplane mode test, download several puzzles as images or PDFs before you travel instead, or look at a dedicated collection built for this exact problem. I've pulled together a much wider list in this list of games that work with zero data, and if you're specifically planning for a flight or a dead zone, my airplane mode tested Android list covers more than just puzzle apps so you're not stuck with one game for nine hours.
If you're setting this up on a Chromebook rather than a phone, the same caching logic applies but the app store behaves differently, which I go through separately in this guide to offline downloads on a Chromebook. And if the whole household is after something for an evening that doesn't need a download at all, this list of browser games that load in seconds is a decent fallback while you're still testing which puzzle app behaves offline.
Frequently asked questions
Do free Sudoku apps work without wifi on Android?
Some do and some don't. Apps like Sudoku.com cache a large batch of puzzles locally so they keep working once you turn the wifi off, but plenty of others only generate puzzles when they can reach a server, so the safest approach is to test one app in airplane mode before you rely on it.
Why does my crossword app stop working on a plane?
Most crossword apps download one puzzle at a time from a server rather than storing a batch of them on your device, so once you've finished the puzzle that was already loaded, there's nothing left to open until you're back online.
How do I check if an app is really offline before I travel?
Open it once on wifi, then switch to full airplane mode (not just wifi off) and try to load at least five puzzles, not just the one already on screen, and close and reopen the app to confirm your progress saved without needing a connection.
Are paid Sudoku and crossword apps more reliable offline than free ones?
Not automatically. Some paid apps from major newspapers still require a daily download because it keeps you connected to their platform, while some free apps generate puzzles locally on the device, so price is a poor indicator and testing with the wifi off is the only way to know for sure.
