Wallet guide

Where to open it

The wallet is a web page, with nothing to install. It opens in browsers on computers and phones, and in the built-in browsers of wallet apps:

• Computer: open wallet.ark0.si in Chrome, Edge, Firefox or Safari.
• Phone: open the same address in the phone's own browser, in Chrome or in Safari.
• Wallet app: MetaMask, TokenPocket, imToken, OKX, Bitget and other wallet apps have a built-in browser, usually on a Browser, Discover or DApp tab. Type wallet.ark0.si in its address bar.

If the browser is too old

The wallet needs Safari 15.4 or later (on an iPhone or iPad, that is iOS or iPadOS 15.4 or later), Chrome or Edge 83 or later, or Firefox 96 or later. On Android, the built-in browser of a wallet app is usually the system WebView. If the page still shows Checking the network… after ten or fifteen seconds, or says the browser is too old, update the phone and its browser, or open the wallet in another browser. On Android, you can also update Android System WebView from the app store.

Two more things

• Do not use a private or incognito window: the browser deletes the wallet when you close it.
• If a link does not open inside a chat app, or is blocked there, open the menu at the top right and choose to open the page in a browser.

Step 1: open your wallet

Open the wallet. When the top of the page shows the Ark-0 test network and its current chain tip, the page is connected. The first time, click Create a wallet. The keys are made at random in this browser, and only the backup code opens the wallet anywhere else.

The page makes addresses that start with tb1z:

• Schnorr address: spends with a Schnorr signature.
• ML-DSA-44 address: spends with an ML-DSA-44 signature, checked by OP_CHECKMLDSA44, an experimental opcode of this test network. It is not part of BIP-360. Blocks are authorized by classical signatures, and from height 20000 they also need M2's ML-DSA-44 block signature. The page shows this address once the chain is six blocks past the height where M1 applies.
• Mixed address: one output with two leaves, both of leaf version 0xe0 (tripwired leaves, an experimental leaf version of this test network, not part of BIP-360), one spent with a Schnorr signature and one with an ML-DSA-44 signature. The operator triggers the drill tripwire at an announced time: until then spends take the Schnorr leaf; after it the wallet takes the ML-DSA-44 leaf by itself, so the coins can still be spent, for a much higher fee. The page shows this address once the chain is six blocks past the height where M3 applies.
• SLH1 address: one output with two leaves at depth one, both of leaf version 0xc0: one spent with an SLH-DSA-SHA2-128s signature, checked by OP_CHECKSLHDSA128S, an experimental opcode of this test network, not part of BIP-360; the other OP_RETURN, which can never be spent. The page shows this address once the chain is six blocks past the height where M4-S applies; when the chain goes back below that (after a reorganization, for example) or M4-S's state cannot be read, the page stops showing the address, and its coins are marked Paused: counted in the balance, not spent. A spend from it carries one SLH-DSA-SHA2-128s signature (7,856 bytes) for each coin it spends; each is made in the background in a few seconds, longer on older phones, and the page shows the progress. Each wallet has one SLH1 address: the payments to it can be linked to each other on the chain, and several of its coins may go into one spend. For a wallet opened by logging in, this address, like the ML-DSA-44 and mixed addresses, has no post-quantum protection (see below). Ark-0 is a test network, for trying out only, which may be reset at any time. Send this address only the coins you want to try M4-S with.

The page tells them apart with four labels, Classical signature, Post-quantum signature · M1, Classical + post-quantum · M3 and Post-quantum signature · M4-S; Why more than one address? above the addresses explains the differences.

All of them belong to this wallet and come back with the same backup code. If you have a backup code already, restore the wallet instead of creating one: see Another device or browser.

A wallet opened by logging in has no post-quantum protection

Log in with your wallet was turned off on 2026-10-14. A wallet opened with it got its seed from your account's signature of a fixed text. Once the account has sent a transaction on any chain, its public key is public; whoever can work out the private key from the public key can make the same signature again and get every key of the wallet, the ML-DSA-44 and SLH-DSA keys too. So such a wallet is always treated as having no post-quantum protection. If your browser still keeps such a wallet, it opens as before, and the wallet page marks it. Do not sign that text on any site again: whoever gets the signature can spend the wallet's coins.

To move to a wallet with its own random seed:

1. Write down this wallet's backup code: with logging in turned off, it is the only way to open this wallet again. If you have signed the migration-readiness declaration with this wallet, revoke that first: on the signing page, click Revoke the signature, and sign again once you have the new wallet.
2. Click Forget this wallet and Delete the keys, then Create a wallet, and write down the new wallet's backup code.
3. Under any of the new wallet's addresses, click Get test coins.
4. To bring the old wallet's coins over too: copy the new wallet's ML-DSA-44 or mixed address and forget the new wallet; restore the old one from its backup code and send the coins at each of its addresses to the address you copied (one send per address, with Send everything ticked); once those sends have confirmed and its balance shows zero, forget the old wallet and restore the new one from its backup code.

Step 2: write down the backup code

Write down the backup code, whether you created the wallet or logged in to it. Once the wallet is open, a note at the top of the page asks you to back it up. Under Backup near the bottom of the page, click Show the backup code. The backup code starts with ark0w1-. Write it on paper, or click Copy and keep it somewhere you trust, such as a password manager.

The backup code is the wallet: anyone who has it can spend the coins. Do not send it to anyone, including someone who says they are support staff or an admin.

Step 3: get test coins

Under any of the addresses, click Get test coins. The faucet opens with that address filled in: pass the human check, then click Claim coins. Each address can claim once every 24 hours. Afterwards, click Back to the wallet on the faucet's page to get back to the wallet.

To try M1, claim to the ML-DSA-44 address and spend from it in step 5: OP_CHECKMLDSA44 then checks that transaction's signature.

If the human check never loads, click Copy next to the address in the wallet, then open the faucet in another browser, such as the phone's own browser, and paste the address there. The coins go to the same address.

Step 4: see the coins arrive

Within seconds of the faucet sending, the wallet shows the transaction under Activity as pending, with the pending amount by the balance: the transaction is in the mempool and not yet in a block. The next block confirms it, usually within two minutes, and it then counts under Confirmed balance for that address. The wallet refreshes every 30 seconds, every 10 while a transaction waits, or click Refresh.

Click View in the explorer to see the unspent coins of that address in the explorer. The explorer does not list an address's past transactions; look a transaction up by its ID instead.

Step 5: send

1. Under Send, pick the address to spend from.
2. Enter the address to pay. To try it out, click Another of my addresses to pay another of your own addresses.
3. Enter the amount, or tick Send everything.
4. Click Review and check the network, the address, the amount and the fee.
5. Click Confirm and send. The page shows the checking, the signing and the broadcast in turn; Sent means it went out. The transaction then shows as pending under Activity, and the balances change once the next block confirms it. View the transaction shows it in the explorer.

The fee is 2 satoshis per virtual byte (2 sat/vB); change too small to be worth sending back is added to the fee. An ML-DSA-44 signature is far larger than a Schnorr signature, so a spend from the ML-DSA-44 address pays a much higher fee. Review shows the actual fee and rate.

The address you pay must be an Ark-0 address, one that starts with tb1q, tb1p or tb1z. Other test networks use tb1 addresses too, and the wallet cannot tell whether an address is on Ark-0, so check it before you send. Addresses in MetaMask and similar apps (0x…) and Bitcoin mainnet addresses cannot receive Ark-0 coins.

Another device or browser

Open the wallet in the other browser or on the other device, paste the backup code under Restore and click Restore the wallet. The addresses and their coins come back. A wallet you opened by logging in can only come back this way now. If that browser holds a wallet already, Restore is not shown: make sure that wallet is backed up or its coins are sent elsewhere, click Forget this wallet, then restore.

You can restore the same wallet in several browsers, but send from one of them only: when two of them spend the same coins, only one of the transactions can confirm.

To stop using the wallet on a device, click Forget this wallet, then Delete the keys. Before that, make sure you have the backup code, or that the coins have been sent elsewhere.

Desktop and Android wallet

Ark-0 Wallet is a wallet you install, for Windows, macOS, Linux and Android, on the same Ark-0 test network as this web wallet. Its keys come from 24 recovery words and stay on the device, in a file encrypted with your password, and it signs there too; every payment is reviewed in the wallet, then confirmed in a dialog of the operating system. It asks both wallet.ark0.si and wallet2.ark0.si for balances and the state of transactions and compares the two answers; a payment is final after 6 blocks, once the wallet has checked those blocks' signatures itself.

1. Open the download page and download the file for your system. It lists each file with its size and SHA-256 and says how to install it; the same files are on the release page on GitHub.
2. Check the file before you install it, as the download page shows: SHA256SUMS is signed with the Ark-0 release key, the key that signs the node releases.
3. Install it and open the wallet. Create a new wallet and write down its 24 recovery words; or choose "Restore a wallet" and enter the words, or paste a backup code of this web wallet, which restores the addresses that web wallet had.

Sign the migration-readiness declaration

The migration-readiness declaration is one sentence:

If you agree with it, you can sign it with your Ark-0 wallet. Every signature is public; as long as you keep the wallet or its backup code, you can revoke yours at any time. Signing or not affects no entitlement.

1. Open the signing page. It is on the standard wallet's site; the Lattice edition's site cannot sign. If this browser holds no Ark-0 wallet yet: if you have one (on the old address too), bring it here first with its backup code (Restore the wallet) on the wallet page; if not, click Create a wallet. Then return to the signing page.
2. Read the points under Before you sign, then click Check the public record. The page downloads the whole public record and compares it in your browser, rather than asking the server about your declaration keys one by one.
3. Click Sign the declaration. The page gets a challenge from the server, does a little work, signs with a declaration key and submits. The work usually takes a few seconds; keep the page in front. It is there to make signing in bulk costly. When the page says it is signed and when the server took it, you are done.
4. To revoke, come back to the signing page and click Revoke the signature.

Before you sign, you may want to know

• It does not touch your wallet app and spends no coins. The declaration is signed with a key the Ark-0 wallet works out in your browser for this purpose only (a declaration key, ML-DSA-44). Neither signing nor revoking makes MetaMask, TokenPocket or any other wallet app ask for a signature or an approval; nothing connects to a wallet app, approves a contract or pays a fee. If a wallet app asks you to sign or approve something on the signing page, that request is not ours: refuse it.
• The signature is good for this sentence only. What you sign is the sentence in both languages; the signing page shows both and their hash. Change any character and the signature no longer verifies. It is not a transaction, does not go on chain, cannot move anything, and authorizes nothing else.
• The private key stays in your browser. The server receives the public key, the signature, the action and the work (and, as any website does, sees your IP address), never your wallet's seed, backup code or private keys. Declaration keys are worked out apart from the keys that receive coins: the public record alone does not tell which wallet address a declaration key belongs to.
• What is public. The public key, the signature, the action (sign or revoke), the hour the server took it, and the challenge and nonce that let anyone check the work all go into the public record, declaration.json, which anyone can download and check offline. We do not publish your IP address or your wallet addresses.
• It is not guaranteed anonymous. The operator and the network services in between may link a signing request to the wallet activity of the same browser.
• The same risk as the wallet page. The signing page and the wallet are one site, so a script of this site can reach the wallet's seed. The site loads only its own scripts: no third-party scripts and no analytics.
• You can revoke. Revoking takes the Ark-0 wallet you signed with, or its backup code. A revoked key no longer counts, and the record keeps its history. To sign again later, the wallet uses a new declaration key.
• The number is not a number of people. The signing page shows how many public keys have a valid signature. One person can make many keys, and the operator can sign with keys of its own too. Please sign once.

Run a node and watch the drill

A node is a program that runs the Ark-0 software and checks every block itself. When the drill tripwire is pulled on 30 October, your node applies the published rules on its own, with no need to trust our sites. The more people watch, the more the drill's record is worth.

You need a Windows, Mac or Linux computer with a network connection. The node is small: the program and the chain take under 200 MB of disk, the node under 100 MB of memory, and the first sync usually a few minutes. The easy way is the witness program: a small program that carries a build of the Ark-0 node for your system, runs from an unpacked folder without installing anything and shows in your browser what your node sees. JOIN.md has every command for running the node yourself, building from source included; the notes below say how to get there on each system. We have run the witness program on Windows, on a Mac with Apple silicon (its Intel build too, under Rosetta) and on Linux on x86_64, where we have also run the Linux steps of JOIN.md; the ARM build for Linux has so far run only under emulation, and the WSL and Docker notes follow Microsoft's and Docker's own instructions without our having tried them, so please tell us about any trouble.

Windows

The witness program needs 64-bit Windows 10 or 11 on an Intel or AMD processor. Double-click it and it starts the node in the background, with no commands to type.

1. Download ark0-witness-0.3.0-win64.zip (about 10 MB). To check it, open PowerShell in your Downloads folder and run Get-FileHash .\ark0-witness-0.3.0-win64.zip; it should print D6656931BEA2EE9EE2659C3D89107C5FD5A146B070B6DC5812274AC151BE606F, as the signed SHA256SUMS on the release page says too.
2. Right-click the zip, choose "Extract All", open the extracted folder (and the folder of the same name inside it, if there is one) and double-click Ark0Witness.exe. Do not double-click it inside the zip: there it cannot find bitcoind.exe next to it, and it asks you to extract first. Extract the zip onto the computer's own drive: on a FAT32 or exFAT drive, such as many USB sticks, the node does not start, and the window shows a Windows error such as "The parameter is incorrect."
3. The program is not code-signed, so Windows may say "Windows protected your PC": click "More info", then "Run anyway". If Windows blocks it with no "Run anyway" (Smart App Control is on), the witness program cannot run on that computer; use WSL as below instead.
4. A console window opens and your browser shows the status page. Keep the window open: closing it stops the node, and so does a sleeping computer. The first sync starts from scratch and usually takes a few minutes, depending on your connection.
5. The page shows which block your node has synced to and how many nodes it is connected to; whether the hash of block 1264 matches Ark-0; once block 30000 (where M3 applies) is reached, that block's hash on your node, with a link to compare it in the explorer; and the state of the two tripwires, with whether elliptic curve signatures in leaves of version 0xe0 are still accepted from the next block. Paste a raw transaction under "Check a transaction" and click "Check", and your node judges it: it is only checked, never sent. Under "Witness report", "Copy" gives you a text to share in the community channels or in a GitHub issue; it holds no IP address and no folder name. All times on the page are UTC.
6. To remove it: close the console window, wait a few seconds, delete the extracted folder, then delete %LOCALAPPDATA%\Ark0Witness (paste %LOCALAPPDATA% into the File Explorer address bar and press Enter to find it). The program writes nowhere else and installs nothing.

Or use WSL. You can also run the Linux build in the Linux that comes with Windows (WSL), on Windows 10 version 2004 or later or on Windows 11, though not on a Windows computer with an ARM processor (such as a Snapdragon). In PowerShell run as administrator, run wsl --install -d Ubuntu-24.04 and restart when asked; if it asks for virtualization, turn it on in the computer's BIOS first. Then open Ubuntu from the Start menu, choose a user name and password, and follow the "Prebuilt binaries or image" part of JOIN.md there, checking and unpacking as the note under Linux below says. Keep one Ubuntu window open, minimized if you like, while the node runs: once all of them are closed, Windows may stop WSL and the node with it. A sleeping computer stops the node too. If Ubuntu 24.04 is installed already, skip the install command. To remove the node, stop it and delete what you downloaded and its data directory; only if that Ubuntu was installed for the node alone and holds nothing else of yours, wsl --unregister Ubuntu-24.04 removes it and everything in it.

Mac

The witness program runs on macOS 14 (Sonoma) or later, on Apple silicon and Intel Macs alike.

1. Download ark0-witness-0.3.0-macos.zip (about 19 MB). Safari unpacks it into your Downloads folder by itself; with another browser, double-click the zip. To check it, run shasum -a 256 ~/Downloads/ark0-witness-0.3.0-macos/* in Terminal: the lines for Ark0Witness and bitcoind should match the signed SHA256SUMS on the release page.
2. Double-click Ark0Witness in the folder ark0-witness-0.3.0-macos. The program is not notarized by Apple, so the first time macOS says it cannot verify it: click "Done" (on macOS 14, "Cancel"), not "Move to Trash". Open System Settings, then Privacy & Security, scroll down to the message that "Ark0Witness" was blocked, click "Open Anyway" and confirm with your password. Double-click Ark0Witness again and click "Open Anyway" (on macOS 14, "Open"). macOS may also ask whether Terminal may access files in your Downloads folder: click "Allow". The node next to it asks for nothing: the program checks it and runs its own copy.
3. A Terminal window opens and your browser shows the status page, the same as on Windows (above). Keep the window open: closing it stops the node (Terminal asks first; click "Terminate"), and so does a sleeping Mac: caffeinate -i in another Terminal window keeps it awake while that runs, though closing the lid still puts it to sleep.
4. To remove it: close the Terminal window, wait a minute for the node to stop, then delete the folder ark0-witness-0.3.0-macos and the folder ~/Library/Application Support/Ark0Witness (in the Finder, choose Go, then Go to Folder, and paste that path). The program writes nowhere else and installs nothing.

Or in Terminal. A file downloaded with curl is not marked as coming from the internet, so macOS asks nothing. These lines download the zip, check it, unpack it and start the program; Ctrl+C or closing the window stops it:

cd ~/Downloads &&
curl -LO https://github.com/duncan0k/bitcoin-p2mr-patches/releases/download/ark0-witness-0.3.0/ark0-witness-0.3.0-macos.zip &&
echo "61a7e1e3070a34e79a596e0e4343c21fccd164e7d4549026b9eb0d1c72d10c98  ark0-witness-0.3.0-macos.zip" | shasum -a 256 -c &&
unzip -q ark0-witness-0.3.0-macos.zip &&
./ark0-witness-0.3.0-macos/Ark0Witness

Or use Docker. To follow JOIN.md instead, run its container image with Docker Desktop, adding --platform linux/amd64 to its docker pull and docker run. The image is built for Intel and AMD processors; on a Mac with Apple silicon (the M series), Docker Desktop runs it through Rosetta: make sure "Use Rosetta for x86_64/amd64 emulation on Apple Silicon" is ticked in its settings. Checking the signature needs gpg: brew install gnupg with Homebrew; without Homebrew, run the two gpg commands in a container, in the directory that holds the downloaded files:

docker run --rm -v "$PWD:/w" -w /w debian:13 sh -c 'apt-get update -qq && apt-get install -y -qq gnupg > /dev/null && gpg --import release-signing-key.asc && gpg --verify SHA256SUMS.asc SHA256SUMS'

A sleeping Mac stops the node: caffeinate -i in a Terminal window keeps it awake while that runs, though closing the lid still puts it to sleep. After a restart, open Docker Desktop, then run docker start ark0.

Linux

The witness program runs on 64-bit Linux with glibc 2.35 or later, such as Ubuntu 22.04, Debian 12 and Raspberry Pi OS (bookworm), or later releases: ark0-witness-0.3.0-linux-x86_64.tar.gz (about 10 MB) for Intel and AMD processors, ark0-witness-0.3.0-linux-aarch64.tar.gz (about 10 MB) for 64-bit ARM, such as a Raspberry Pi with the 64-bit system. In a terminal, in the folder you downloaded it to, these lines check it, unpack it and start the program:

echo "f85ac708ba7a35b735a7bf841820c87d92c776d9d69f569932120f8f5874037d  ark0-witness-0.3.0-linux-x86_64.tar.gz" | sha256sum -c &&
tar -xzf ark0-witness-0.3.0-linux-x86_64.tar.gz &&
./ark0-witness-0.3.0-linux-x86_64/ark0-witness

For ARM, put aarch64 in place of x86_64 in all three lines and a768ce5b0976a8187ce4c2a29f75578f6bdd36a0d4926ac6f5be7e174bcfcb09 in place of the SHA-256. On a desktop, the status page opens in your browser; otherwise, open the address the program prints in a browser on the same computer. If it stops instead and prints a chmod command for your folders, run that command, then start the program again. Keep the terminal open: closing it, or Ctrl+C, stops the node. On a computer without a screen, such as a Raspberry Pi you reach over SSH, forward the page's port: if the program printed http://127.0.0.1:41234/..., run ssh -L 41234:127.0.0.1:41234 you@raspberrypi on your own computer and open the printed address there, unchanged; to keep the program running after you log out, start it inside tmux or screen. To remove it: stop it, then delete the unpacked folder and ~/.local/share/Ark0Witness.

The prebuilt binaries of JOIN.md need Ubuntu 24.04 or Debian 13 on x86_64. On older systems, such as Ubuntu 22.04 or Debian 12, use the image or build from source, both in JOIN.md. For ARM machines such as a Raspberry Pi, JOIN.md has no prebuilt binaries; the witness program above carries a node for them.

Wherever you follow JOIN.md's prebuilt binaries, on Linux or in WSL, run its check and unpacking as one chain, so that nothing is unpacked unless the first check passes:

sha256sum --ignore-missing -c SHA256SUMS &&
tar -xzf ark0-node-m4r-x86_64-linux-gnu.tar.gz &&
sha256sum --ignore-missing -c SHA256SUMS

A node from before

A node set up before 30 October runs the build ark0-node-m3 or an earlier one. From height 51000 it stops at the first block with a rescue spend, so replace it with ark0-node-m4r before then. The simplest way is to delete its chain data, the folder signet in its data directory, and let the new build sync from the start, which takes a quarter of an hour or so; keep the configuration. JOIN.md, section 5, has the other way: an upgrade in place, with one start with -reindex-chainstate for a node of M3. With the witness program, close the old one and start 0.3.0 as above.

Check it first

With the witness program, its page makes these checks for you; skip this part.

Below, bitcoin-cli stands for the command JOIN.md gives you: the binary with your -datadir, or docker exec ark0 bitcoin-cli -datadir=/data.

• bitcoin-cli getblockchaininfo: once blocks equals headers and initialblockdownload is false, the node has caught up.
• bitcoin-cli getblockhash 1264 gives 00000036e6e81d9884217ca9918e38b9683617b41195a6d4ccc4c4696b31e9d4. Another hash means the node is not on Ark-0.
• bitcoin-cli gettripwireinfo shows height 30000 and leaf_version e0. Since the drill on 30 October, the tripwire labelled drill is in state missing, the other one unspent, and ec_disabled_next_block is true. Until the node has synced past block 36897 it shows both unspent and ec_disabled_next_block false, and until block 15748 both missing; both are expected. The M4-R build also shows a rescue object with height 51000.

What to watch

The tripwire drill took place on 30 October: block 36897 spent the drill tripwire, and since the next block elliptic curve signatures in leaves of version 0xe0 fail. Next is M4-R, the rescue lane, from height 51000: expected around 15 November and not before 14 November; the community channels give the time.

With the witness program, its page shows step 1 (the version, 0.3.0) and step 3 (the block count going past the block with the rescue); step 2 takes the node's commands, which the program does not show.

1. Before height 51000, check that the node runs the new build: bitcoin-cli getdeploymentinfo lists p2mr_rescue with type buried and height 51000.
2. Once the chain has reached height 50999, p2mr_rescue in bitcoin-cli getdeploymentinfo shows active true, and the rescue object of bitcoin-cli gettripwireinfo shows active_next_block true. Both describe the next block, 51000, the first under the rule.
3. After height 51000, at a time we announce beforehand, we rescue the two drill coins in one transaction with rescue proofs, and post its txid and the hash of its block in the community channels. bitcoin-cli getblock BLOCK_HASH 1 with that hash should answer with more than 0 confirmations: your own node took the first block with a rescue spend. The transaction itself can be opened in the explorer, which shows the two coins it rescues.
4. The proof made off the chain is already public: check it yourself with any of the three verifiers, Python, Rust or Go, as the rescue drill's page shows.
5. If you like, share the output of steps 1 to 3 (text or a screenshot) in the community channels or as an issue on the patch repository. The public record says only how many outside nodes watched, with no names and no addresses.

Your node can still judge the M3 drill's witness transaction until 30 November; NETWORK.md, "What the chain shows", has it.

An Android phone?

Not for now, and not an iPhone either. Ark-0 publishes binaries for Windows, Mac and Linux computers only, nothing made for a phone, and phones stop programs that keep running in the background. With a phone you can still take part in the drill: try the mixed address in the wallet and watch the blocks in the explorer. What you see there, though, is what our sites report, not a check of your own.

Common problems

The addresses start with tb1z, not bc1z

That is expected. tb1z and bc1z are the same kind of address (P2MR), written for two networks: tb1z for a test network, bc1z for Bitcoin mainnet. Ark-0 is a test network, so the wallet's addresses start with tb1z.

The page stays at Checking the network…

The browser may be too old for the wallet, or it blocks the page's script. Update the browser, or use another one: see Where to open it.

There is no Log in with your wallet

Log in with your wallet was turned off on 2026-10-14: a wallet opened with it has no post-quantum protection (see A wallet opened by logging in has no post-quantum protection). A wallet you opened that way still opens in a browser that keeps it; anywhere else it comes back with its backup code. Without the backup code, create a wallet and claim test coins again.

It says the wallet is open in another tab

One tab of a browser runs the wallet at a time. Close the other tabs that have the wallet open (the built-in browser of a wallet app may keep several tabs too); this page then takes over.

It says the browser does not let the page keep data

Leave private or incognito mode, allow this site to keep data in the browser's settings, or use another browser.

The coins were claimed, but the balance has not changed

Look under Activity first: pending means the transaction is in the mempool, and it counts in the balance once the next block confirms it. If nothing shows there, click Refresh; you can also click View the transaction on the faucet's confirmation page to see whether that transaction has confirmed.

It cannot tell whether the node took the transaction

Click the transaction's ID on the page to look it up in the explorer. This browser sets its coins aside for ten minutes and does not spend them meanwhile. If the explorer still does not know the transaction after that, send again.

It says the coins changed since the review

The balance has just changed. Click Back, then Review again, then confirm.

Copy does nothing, or it says Select and copy it by hand

The page selects the text for you: press and hold it (on a computer, right-click it) and copy it.