Tap the + button at the bottom of the screen. You have three ways to add a book:
Scanning and ISBN lookup both need an internet connection, since they fetch the title, author, page count, and cover from Open Library or Google Books. If the lookup can't find a match, you're offered an Add it manually button instead of being stuck.
Whichever route you take, you land on the same form to confirm or fill in:
| Field | Notes |
|---|---|
| Cover | Tap it to replace with a photo from your device. Any cover found online is downloaded and stored on your device, so it won't disappear later if the source changes. |
| Title | Required. |
| Author | |
| Series | Optional. |
| Total pages | |
| Status | Want / Reading / Read — a three-way toggle. |
Saving fills in sensible dates automatically: date added is today, date started is today unless it's on your Want list, and if you mark it Read right away, the finish date and current page are set for you too. You can always adjust any of this later from the book's detail page.
Four tabs sit along the bottom of the app, and you can swipe left and right between them:
Tap any book anywhere in the app to open its detail page.
This is where the actual day-to-day use happens. From here you can:
Once a book is marked Read, the progress slider is replaced with a simple "✓ Completed" line, so there's nothing left to accidentally bump out of place.
Turn this on in Settings and Margins checks in once a day, around 7:00 PM. It only sends a notification if you have a book marked Reading and haven't logged any progress yet that day — otherwise it stays quiet. The message adapts to how long it's been:
On newer versions of Android, you'll be asked to allow notifications the first time you turn this on. Turning the toggle off cancels it entirely.
Four palettes are available, each with its own light and dark mode (the theme and the light/dark switch are independent, so you can pair any theme with either mode):
| Theme | Feel |
|---|---|
| Classic parchment | Warm paper, oxblood and gold — the original look. |
| Fjord | Glacier blue and brass, with a rune-inspired display font for titles. |
| Marginalia | Bone white with an editorial vermillion accent. |
| Field notes | Sage, ink, and terracotta — a botanical field-journal feel. |
Star ratings always stay gold, no matter which theme you're using.
Everything lives on your device, so it's worth backing up from time to time — especially before switching phones.
Once a valid file is loaded, this permanently deletes everything currently in the app before importing it — that part genuinely can't be undone. Export a current backup beforehand if you're at all unsure.
When you scan or type in an ISBN, Margins checks two free catalogs to fill in the title, author, page count, and cover: Open Library and Google Books. You can control this from Settings.
The Cover & metadata source dropdown picks which catalog is tried first. Whichever one you don't pick is still tried automatically if the first one comes back empty — so there's no separate "auto" option; that fallback always happens.
Every ISBN encodes the country its edition was registered in — except for English-language books, where the same numbering is shared across the US, UK, Australia, Canada, and New Zealand, so it's genuinely ambiguous which cover to prefer. That's what the Google Books region dropdown is for: it only comes into play for English-language ISBNs, letting you choose which edition's cover you'd rather see. For every other language, the correct country is detected automatically from the ISBN itself, and this setting has no effect.
Open Library occasionally only has a cover attached to a different printing of a book, not the specific edition your ISBN identifies. Margins deliberately does not use that mismatched cover — it would rather show no cover (which you can replace with your own photo) than a confidently wrong one. If that happens, try switching the source to Google Books in Settings and using "Refetch cover & details" on the book's page, since Google's results are matched to your exact edition.
Margins works out of the box with no setup — Open Library needs no key at all, and Google Books allows a small number of anonymous lookups shared across everyone using the app without one. That shared quota can run out or get temporarily flaky at busy times, though, so if you plan to add a lot of books, a free key of your own is worth the five minutes it takes.
An unrestricted API key will work for anyone who gets hold of it, so Google lets you lock it to a specific app. You don't need Android Studio, a computer, or any developer tools for this — just two values, both fixed for every copy of Margins downloaded from the Play Store:
| Package name | com.miroda.margins |
|---|---|
| SHA-1 fingerprint | REPLACE_WITH_PLAY_SIGNING_SHA1 |
Every phone that installs Margins from the Play Store gets the exact same signed app, so this SHA-1 is the same for you as it is for every other reader of this page — just copy it in.
See how lookup works above — for English-language books, try setting your Google Books region to match the edition you own. If a cover still looks wrong, tap the cover on the book's detail page and replace it with your own photo; that always takes priority.
Some editions simply don't have a cover uploaded to either catalog. Margins would rather leave it blank than guess with a mismatched one — replace it with a photo of your own copy from the book's detail page.
Use the Test key button in Settings — it shows Google's actual error message rather than a generic failure, which usually tells you exactly what's wrong: an invalid key, the Books API not being enabled on your project, or (if you've restricted it) trying to test it somewhere other than the real app.
Some books, especially small-press or self-published titles, aren't listed in either catalog. Use Add it manually from the lookup screen.
Check that notification permission is granted to Margins in your phone's system settings, and that you don't already have a book logged for the day — the reminder deliberately stays silent once you've logged progress.
Export a backup on your old device, install Margins on the new one, and use Import from backup (or Replace entire library if it's a brand-new install). Covers are embedded in the backup file itself, so they'll come across too.