Densa Deck — how it works
Everything the app can do, on the phone and on the desktop, in one page. Each entry is tagged with what it needs: nothing, a PC in reach, or a Pro licence. If something here does not match what your app does, the app is right and this page is out of date — say so.
Needs a PC works when the desktop app is running and paired. Still free.
Pro needs a Densa Deck Pro licence, activated on the desktop.
Getting started
The phone app works entirely on its own. A PC is an addition, not a requirement.
This phone only, or with a PC Free
The first thing the app asks is whether you have a desktop. Choose This phone only and nothing ever asks again — no pairing, no network, no account. You can connect a PC later from Settings, and you can disconnect one the same way.
The card index Free
Before scanning works, the phone needs to know what cards exist. It downloads that once — about 79 MB from Scryfall, or faster from your PC if you have one paired. After that, scanning, searching and pricing all work with no signal at all.
Your collection lives on the phone Free
Everything you scan is stored in a single database on the device. The app is offline-first: scanning, browsing, deck building and prices all work with no signal at all. Edits made offline are kept and exchanged with the desktop when it is next in reach; nothing is lost in the meantime and nothing is uploaded anywhere.
Scanning cards
The phone reads the card itself. The set code and collector number along the bottom edge are what identify it exactly.
Capture, or auto scan Free
Capture takes one picture. Auto scan keeps taking them while you feed cards past the camera, and stops on its own if the camera freezes or nothing is being read. The phone vibrates when a card is seen, not on every frame.
Add cards, or tag what you own Free
Add cards files each scan into the collection you pick. Tag what I own puts cards you already have into a group — a bundle to sell, a pile to lend — without adding or removing anything. Tagging needs a PC. Needs a PC
Foil, and prerelease promos Free
Two switches at the top of the scanner, because neither can be read off the card reliably. Foil stays on until you turn it off — foils come in runs — and the green confirmation says FOIL so a mistake is one card old rather than thirty. Prerelease promo files the date-stamped printing instead of the ordinary one.
How many, and which printing Free
When a card needs a choice, the picker shows the actual card art for each printing, with the set name, number and rarity colour. Set a quantity first to file several at once. For a card with hundreds of printings there is a set box to narrow it down.
Basic lands Free
An Island has 671 printings in the index, so the name alone cannot identify one. If the collector number will not read, the app falls back to the artist and copyright year along the bottom edge, which narrows most basics to a handful of cards you can pick by sight. Cards printed before 1995 carry no set code at all, and for those this is the only route.
Typing a card in Free
Under the camera there is a name box. Some cards the camera was never going to place — a worn land, a card in a heavy sleeve — and typing four letters is faster than fighting it.
Your collection
Collections and groups Free
A card is filed in one place — that is where the physical card lives — and can be tagged into any number of lists on top of that. Deleting a group needs a PC. Needs a PC
Browsing and searching Free
Search by name, rules text, colour, type, rarity, set or mana value. Only mine narrows it to what you own, and can be pointed at a single collection — “only the cards in my Modern binder”.
Wrong printing, or wrong finish Free
Open a card you own and you can move it onto a different printing, or mark it as foil after the fact — all of it, or just one copy of four. Nothing is deleted on the way: the new stack is created before the old one is reduced.
Card art Free
Every picture comes from Scryfall and is cached on the device after it has been seen once. Nothing is bundled into the app and nothing is re-hosted.
Building decks
Browse, or paste a list Free
Search the catalogue and tap to add, or paste a decklist from
anywhere — set codes, collector numbers and Moxfield-style
*F* foil markers are all understood and stripped off
the card name. The text box is the deck; editing it and saving
rewrites the list.
Tap to add Free
A checkbox under the filters. With it on, a tap adds the card immediately at its cheapest printing rather than opening it to be read. Hold a card to open it anyway — to read it, swipe the printings, or take one out.
Scanning straight into a deck Free
Open a deck and there is a scanner with the same camera, picker and switches. Two modes: From my collection puts the card in the deck and leaves your collection alone, and New card files it as well. If you scan something that is not catalogued, it says so and offers to file it — or to put it in the deck anyway, which is the right answer for a proxy or a borrowed card.
Commander, colours and deck art Free
Set a commander and the browser locks to its colour identity, greying anything outside it with a reason rather than hiding it. The deck shows its colours as pips with a count of each, so you can see a splash from an even pair. Any card in the deck can be chosen as the deck’s picture — it does not have to be the commander.
Foil slots Free
A deck slot records which finish is going in the sleeve, so your
foil copy and your plain one are two different slots, counted and
priced apart. The readable decklist stays clean — no
*F* down the side — and the finish is restored
when the text comes back.
Deck and sideboard Free
A toggle above the cards switches between the maindeck and the
sideboard, and everything you add goes to whichever
is selected. Both are counted together when working out what you
still need to own — three in the deck and one in the board is
four copies to find. Pasted lists understand a
Sideboard heading, and saving writes one back out.
What you still need Free
The deck is checked against what you own and tells you the shortfall, plus format warnings — size, copy limits, colour identity.
Prices and value
Where the numbers come from Free
Scryfall. Prices arrive with the card index and are refreshed for the cards you own and the cards your decks point at — a couple of requests rather than another download. There is a button in Settings, and it happens along with the card check when prices are more than a week old.
A foil is priced as a foil Free
Where the copy on your shelf is the shiny one, the deck is valued at the foil price. Where you own both and the slot does not say which, it takes the lower number: a total that guesses upward reads as a valuation and is a wish.
A card with no price is not free Free
Cards Scryfall has no price for are counted and reported separately — “3 cards couldn’t be priced” — rather than folded in as zero.
The card index
Keeping up with new sets Free
Settings can check whether a set has come out that the phone does not have. Checking is tiny; downloading is not, so it never downloads without asking. You can opt in to it checking for you — it follows Scryfall’s real release calendar, and looks at least once a quarter regardless.
Sets that will never arrive Free
The index keeps English paper cards. A few released sets have none — Foreign Black Border, Renaissance, Rinascimento and others are non-English printings of cards that exist in English elsewhere. After a complete download the app writes those off so it stops reporting them as missing.
What a PC adds
All of this is still free. The desktop app is a free download; a licence only matters for the Pro section below.
Deck analysis and suggestions Needs a PC
Mana curve, archetype detection, colour and type breakdowns, and recommendations for what to add or cut. The phone asks the desktop for these; it cannot compute them alone.
Combo detection and Rule 0 Needs a PC
Two-card and longer combos in your deck, near-misses you are one card away from, and a pre-game disclosure sheet naming the lines. Combo data is from Commander Spellbook.
Bracket fit Needs a PC
Where the deck sits on the 1–5 Commander bracket scale, and what to change if it is pitched wrong.
Building from your collection Needs a PC
Ask the desktop to assemble a deck out of what you actually own. The judging is over the whole catalogue, which is why it needs the machine with the whole catalogue on it.
Two devices, one collection — syncing Needs a PC
Edits sync both ways as events rather than as totals, so a card added on the phone with no signal and a card added on the PC at the same time both survive the sync rather than one overwriting the other. Settings shows what each device thinks you own, which is the only place that can tell you they disagree.
Exports Needs a PC
Decklists out to MTGA, MTGO and Moxfield formats, and reports as JSON, Markdown or HTML.
Densa Deck Pro
A one-time purchase, activated on the desktop. No subscription, no server, and it keeps working offline. The phone picks it up on the next sync.
What Pro adds
All of it on the desktop. The phone shows the results when the desktop is in reach.
Goldfish simulation Pro
Play the deck out against no opposition, thousands of games, and see how fast it does what it is trying to do — including how often it assembles a combo and on which turn.
Matchup gauntlet Pro
The deck against eleven archetype profiles, with win rates and the reason each game ended.
Probability tools Pro
Opening-hand simulation, mana development, and the odds of having a given card by a given turn.
Deep analysis Pro
Synergy, castability, mana base quality and a 1–10 power level rating, plus exporting the full report.
Version history Pro
Save a deck as a version, compare any two, see what a change did to the deck’s power and whether it broke a combo.
The analyst and coach Pro
A local AI that has read your deck: explain why a card is in it, compare two decks in prose, and answer questions about the list. It runs on your machine — nothing is sent anywhere.
More saved decks and groups Pro
Free keeps a limited number of saved decks and groups of your own; Pro removes the limit. Scanning, filing and the size of your collection are unlimited either way. Settings on the phone shows your exact allowance.
What it will not do
Worth knowing before you go looking for them.
Guess at a card
The phone matches exactly or not at all. A card it cannot place is offered as a list to choose from, or refused with the reason — it never files a card it is not sure about. Fuzzy name matching lives on the desktop, where a person is looking at the screen.
Read a foil off the card
The foil marker in the collector line is the one glyph the recogniser reliably loses. That is why there is a switch rather than a guess.
Work out which copy is in a deck when you own both
If you own a foil and a plain copy of the same printing and the deck slot does not say which, the app cannot know. It takes the lower price rather than the flattering one. Set the finish on the slot to be exact.
Resume an interrupted index download
A bulk file has to be read from the start, so an interrupted download starts that file again. The printings are fetched first, so scanning works even if the second half is interrupted.
Record a card that does not exist
Once the index knows which printings come in foil, the app will not let you record a foil of one that was never printed that way.
When something goes wrong
A land will not scan
Basics need the artist line if the collector number will not read, and that needs an index downloaded since the app learned to keep artist names. Refresh the card index in Settings. The app says so explicitly rather than blaming the card.
A card scans as the wrong version
Open it in your collection and change the printing — the quantity, finish, condition and collection all travel with it.
Prices are zero, or missing
Prices only reach the index with a download. Use Update prices now in Settings, which fetches the cards you own and the cards in your decks in a couple of requests.
The phone cannot see the PC
Settings shows what every address did when asked, rather than one word. The usual causes: the desktop app is not running or phone scanning is off, Tailscale is not running on the phone, or the PC has moved to a different address since you paired.
A scan says it read the wrong thing
When the app cannot place a card it quotes what it actually read off it. That line is the useful thing to report — it is the difference between a bad photograph and a card the index does not have.
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Card data and images from Scryfall. Combo data via Commander Spellbook (MIT, © 2023 Commander-Spellbook). Densa Deck is unofficial Fan Content permitted under the Wizards of the Coast Fan Content Policy. Not approved or endorsed by Wizards.