Wallet tracking
public addresses, read-only.
Users can watch the balance of any public address on 9 chains. The app never asks for a private key or seed phrase, never signs and never sends anything.
01Read-only by design
A user adds a label, a chain and a public address. The backend looks up the balance and prices it. That is all: there is no wallet creation, no import of keys, no signing, no sending, no swapping and no custody anywhere in the code (docs/CONTRACT.md §0, firebase/functions/src/api/wallets.ts).
- Tracked addresses are stored on the device (label, chain, address). Nothing about them is stored on the server, unless the user's optional cloud backup is on (users/{uid}/sync, readable only by that user).
- Lookups are cached for 120 seconds per chain and address in the server's memory, and sent with
Cache-Control: private, so an address is never held in a shared CDN cache. - Each wallet has a link to the chain's public block explorer.
02Chains and default endpoints
| Chain | Native coin | Default endpoint | Explorer |
|---|---|---|---|
| Ethereum | ETH | https://ethereum-rpc.publicnode.com | etherscan.io |
| Base | ETH | https://base-rpc.publicnode.com | basescan.org |
| Arbitrum One | ETH | https://arbitrum-one-rpc.publicnode.com | arbiscan.io |
| OP Mainnet | ETH | https://optimism-rpc.publicnode.com | optimistic.etherscan.io |
| Polygon | POL | https://polygon-bor-rpc.publicnode.com | polygonscan.com |
| BNB Smart Chain | BNB | https://bsc-rpc.publicnode.com | bscscan.com |
| Avalanche C-Chain | AVAX | https://avalanche-c-chain-rpc.publicnode.com | snowtrace.io |
| Solana | SOL | https://api.mainnet-beta.solana.com | solscan.io |
| Bitcoin | BTC | https://mempool.space/api (Esplora-style REST) | mempool.space |
Address formats checked before any lookup: EVM 0x + 40 hex characters; Solana base58, 32 to 44 characters; Bitcoin bech32, P2PKH or P2SH. Bitcoin extended public keys (xpub) are not supported. A Bitcoin balance is confirmed plus mempool.
03Verified tokens only
Spam tokens never appear. On EVM chains the backend checks balances (one Multicall3 batch, contract 0xcA11bde05977b3631167028862bE2a173976CA11) only for token contracts that CoinGecko lists for that chain among the top 250 coins. On Solana, SPL Token and Token-2022 accounts are shown only when the mint is in the same verified set; other tokens are counted and reported as hidden (hiddenUnverified). Prices come from the market data.
This means smaller tokens outside the top 250 are not shown, even if they are legitimate.
04Console settings
Console → Wallet chains:
- Chains offered: switch any of the 9 chains off; the app hides it.
- RPC URL per chain and the Bitcoin API base URL: empty = the public default above. They are stored like secrets (owner only, write-only) because provider URLs often contain a key. The Test button asks for the latest block (or the Bitcoin tip height). Status checks every override.
How many wallets a user may track is set under Pro and purchases (free: 1, Pro: 20 by default). The app enforces this limit itself, because wallets are stored on the device.
05Public endpoint limits
publicnode, Solana mainnet-beta and mempool.space are free public endpoints with their own rate limits and terms, and may be slow or refuse requests under load. For a busy app, put your own RPC URLs from an RPC provider into the console. Those providers bill you directly.