A harbour for deals between blockchains

Make a deal across chains, on an offer anyone can check.

Write a buy or sell offer, sign it with your wallet and share it as a link. Whoever gets it can check that it is genuine and fairly priced before they deal.

Ed25519 signatures checked in your browser · live prices from Hyperliquid and Jupiter · nothing is ever moved or held

Write an offer Check an offer
Tide · SOL—
Of 24 h range—
Planks laid0 / 20
LatestReading the market…

The tide follows SOL's live price inside its 24-hour range. Each offer that passes its signature check lays two planks; each buy and sell that meet in price closes the span.

How it works in 3 steps

  1. Pier 1

    You write the offer

    What you give, what you want, your price, on which chains.

  2. Pier 2

    Your wallet signs it

    A free signature proves the offer came from your address.

  3. Pier 3

    You share one link

    Anyone can check signature, expiry and price against the market.

Nothing is moved or charged. Signing an offer is a free message signature, not a payment.

Tide table · live

Every offer is measured against the open market.

What this does: shows the live prices every offer on this site is compared with, refreshed every 15 seconds.

Mid prices for BTC, ETH, SOL, BNB and HYPE come from Hyperliquid's public order books. Solana tokens such as USDC, JUP and BONK come from Jupiter. The curve is SOL over the last 24 hours, hour by hour.

24 h low —24 h high —
AssetNow (USD)24 hSource

Waiting for the first reading…

How a deal crosses

From your dock to theirs, in four checks.

  1. 01

    Write it down

    The offer is plain text: side, amount, chains, price and an expiry time. You can read every word you sign.

  2. 02

    Seal it with your wallet

    Your wallet makes an Ed25519 signature of that exact text. Change one character and the seal breaks.

  3. 03

    Send it across

    The offer and its seal travel as one short code or link. Chat, email, a post, or a Solana Memo: any channel works.

  4. 04

    They check before they deal

    The other side's browser re-checks the seal, the clock and the price against the live market, then decides.

Tool 1 · Offer board

The offer board

What this does: lists every offer you have written, opened or found on chain, re-checks each signature, and marks buys and sells that meet in price.

Example offers are signed seconds after the page loads, in your browser, by a throwaway key that is never stored. They show how the board works and are labelled Example. Nobody stands behind them.

Tool 2 · Write and sign

Write an offer

What this does: turns your terms into a short text, has your wallet sign it, and gives you a link anyone can check.

I want to
Price per unit (USD) Market: —
Connect a wallet to sign as yourself. "Try an example" signs with a throwaway browser key.
Exact text your wallet will sign0 bytes

        

        
      

    

  





  

    

      

        
Tool 3 · Check before you deal

        
Check an offer

        
What this does: tells you whether an offer someone sent you is genuine, still open, fairly priced, and backed by real funds on Solana.

      

      

        
        
      

    

    

      

        
        

        
        
      

      

        
Results appear here: signature, expiry, price against the market, and whether the signer holds what they offer.

        
        

      

    

  





  

    

      

        
Tool 4 · Fair price

        
Is this price fair?

        
What this does: compares any quoted price with the live market and tells you, in plain words, how far off it is.

      

      

    

    

      

        

          
          
        

        

          You would be
          

            
            
          

        

        
        

        
      

      

        
Market now—

        
          
          
          
          
          market
          -5%-2%+2%+5%
          quote
        
        

          
Difference—

          
On your amount—

          
24 h move—

        

        
Enter a price to compare.

      

    

  





  

    

      

        
Tool 5 · Harbour log

        
Offers written on Solana

        
What this does: reads the public notes (Memos) an address has written on Solana and picks out Bridgebook offers, checking each one.

      

      

    

    

      

        
        

        
        

          
Post your offer on chain (optional)

          
Writes your latest signed offer into a Memo from your own wallet, so it stays public and timestamped. It sends nothing to anyone. Network fee about 0.000005 SOL.

          
          

        

      

      

        
Notes will appear here

        
    
        
    
      
    
    
    
  
    

    

    
  
    
    
    Flowcharts
    
    
    Two charts: how a deal flows, and where things go
    
    
    
      
    How it works
    From your terms to the other side's decision. Every check runs in the reader's own browser.
    
      
    
    
    
    
      
    Where the data and money go
    Live sources feed your browser. Funds never pass through Bridgebook: the trade settles directly between the two people.
    
      
    
    
  
    

    

    
  
    
    
    Roadmap
    
    
    What works today, and what comes next
    
    
    Done means it works on this page right now. Planned means not built yet, so no dates are promised.
    
    
      
      
    1. Phase 1 · Live
      Signed offers
      • DoneWrite an offer and sign it with any Solana wallet
      • DoneShare it as a link or code, no server database
      • DoneEd25519 check with our code plus the browser's own
      2. 
      
    2. Phase 2 · Live
      Checks before a deal
      • DonePrice against the live market (Hyperliquid, Jupiter)
      • DoneBacking check of the signer's Solana balance
      • DoneBoard that marks buys and sells that meet in price
      3. 
      
    3. Phase 3 · Live
      On-chain notes
      • DonePost an offer as a Solana Memo from your own wallet
      • DoneRead and verify offers from any address's Memos
      4. 
      
    4. Phase 4 · Next
      More signers
      • PlannedCheck offers signed by Ethereum wallets (EIP-191)
      • PlannedBitcoin message signatures for the BTC side
      5. 
      
    5. Phase 5 · Later
      A shared harbour
      • PlannedOpt-in public board built only from on-chain Memo posts
      • PlannedPartial fills and counter-offers that reference the original
      6. 
    
    
  
    

    

    
  
    
    
    
      
    Tokenomics planned
    
      
    One fixed supply, launched fairly
    
      
    The coin has not launched yet. This is the planned structure: a typical bonding-curve fair launch where everyone buys at the same public price. Nothing here is a promise of returns.
    
      
      
        
    • Total supply1,000,000,000
      • 
        
    • PresaleNone
      • 
        
    • Team allocation0%, unless bought on the curve like anyone
      • 
        
    • Mint authorityOff: no more can ever be made
      • 
        
    • Freeze authorityOff: nobody can freeze your coins
      • 
        
    • Liquidity at graduationLocked or burned
      • 
      
    
      
    
    
    
    
      
        
        
        
        100%
        one public price
      
      
      
        
    • Sold on the bonding curve79.3%
      • 
        
    • Liquidity pool at graduation20.7%
      • 
        
    • Team, presale, insiders0%
      • 
      
    
      
    Bonding curve split shown is the common pump-style model (about 793M sold, 207M to the pool).
    
    
    
  
    

    

    
  
    
    
    Plain words
    
    
    The words on this page, explained
    
    
    
      
    Chain
    A blockchain such as Solana, Ethereum or Bitcoin. A cross-chain deal means one side pays on one chain and the other side on another.
    
      
    Offer
    A short text saying what someone will give, what they want and at what price, until a set time.
    
      
    Signature
    A 64-byte stamp only the owner of a wallet can make. If the text changes by one letter, the stamp no longer fits.
    
      
    Ed25519
    The signature method Solana wallets use. This page checks it with its own code, plus your browser's built-in check where available.
    
      
    Wallet address
    Your public account name on Solana. Safe to share; it can't be used to spend.
    
      
    Market price
    The middle between the best buy and sell price on a big public market right now.
    
      
    Premium / discount
    How far an offer is above or below that market price, in percent.
    
      
    Memo
    A short public note stored inside a Solana transaction. Posting one costs a tiny network fee.
    
      
    Mainnet
    The real Solana network, where real money lives. Everything here reads mainnet.
    
    
    
  
    

    

    
  
    
    
    
      
    Questions
    
      
    Asked at the harbour
    
    
    
    
    
      
    What is this, in one sentence?
    A notice board for buy and sell offers between blockchains, where every offer carries a wallet signature so anyone can check who made it and whether its price is fair.
    
      
    Is it safe? Does it touch my money?
    Bridgebook never moves, holds or asks for your funds, and never asks for a seed phrase. Signing an offer is a free message signature, not a transaction. The only transaction on the site is the optional "post on chain" step: it writes a short Memo from your own wallet, costs a network fee of about 0.000005 SOL and sends nothing to anyone. Your wallet shows you exactly what you approve.
    
      
    So how does the trade itself happen?
    Off this site, between the two people, using whatever method they trust (for example paying in small steps, or a third party both sides know). Bridgebook does not settle trades. It answers the questions you should ask first: is this offer really from that address, is it still open, is the price sane, and does the seller hold what they offer.
    
      
    Where are the offers stored?
    In the link itself. The whole offer and its signature fit inside the code after #o=, so there is no server database to trust. Your own offers stay in this browser tab, and on Solana if you choose to post one.
    
      
    What does "verified" mean, exactly?
    That the signature matches the address written in the offer, so only that wallet could have produced it. It does not mean the person will honour the offer, or that they are who they say they are.
    
      
    Where do the prices come from?
    Hyperliquid's public mid prices for BTC, ETH, SOL, BNB and HYPE, and Jupiter's price feed for Solana tokens. They refresh every 15 seconds while the page is open.
    
      
    Why does the backing check only work for Solana?
    Because this site reads Solana mainnet only. For the other chain, ask for proof another way, or use a block explorer for that chain.