01 · Mechanics

How it works

One transaction does two things: your swap, and the investment of the change it leaves behind.

The round-up

Crumble works in dollars. When you enter a swap, the app prices what you are spending against the pool, rounds that dollar figure up to your chosen step, and the difference is your change.

Steps are $1, $5 or $10. If your swap already lands exactly on the step there is no change that time, and Crumble takes nothing. There is also an invest extra field: a flat amount added on top of the change, for when the round-up alone feels too small to bother with.

The change is charged in the token you are paying with, not in dollars. The app converts the dollar figure into pay-token units in the same proportion as your swap, so paying in ETH means the change comes out of ETH.

Your basket

Before your first round-up you pick what the change buys: between one and eight Stock Tokens, with weights that add up to 100%. The basket is stored on chain against your address, so it follows your wallet and not the browser you set it in.

You can change it whenever you want. A new basket applies to future round-ups; it never touches what you already hold.

One transaction, four moves

1. Your swap goes through

   The vault routes it on Uniswap v3 with the minimum output your slippage setting allows, and the tokens you bought land in your wallet — not in the vault.

2. The fee comes off the change

   One percent of the change, in the token you paid with, goes to the treasury. Nothing is taken from the swap itself.

3. The rest is split by your weights

   Each leg buys its Stock Token from its Uniswap v3 pool. The last leg gets the exact remainder, so nothing is lost to rounding.

4. The stocks are credited to you

   The contract records what actually arrived — not what was quoted — against your address. That balance is yours to withdraw at any time.

Because it is one transaction, there is no waiting, no queue and no off-chain worker holding your money between steps. When the transaction confirms, the stocks are already yours.

When a leg cannot be bought

Sometimes a pool is too thin, the price moves past your slippage, or a Stock Token is no longer listed for new buys. That leg is skipped, and the rest of the basket is bought as normal.

The skipped share is not lost and does not stay with us. It is credited to you in the token you paid with, sits in the vault beside your stocks, and comes out through the same withdrawal. The app tells you before you sign which leg has no route.

Getting it out

Withdraw any single token and any amount, or empty the whole vault in one call. Delisting a Stock Token stops new buys of it and has no effect on withdrawals — what you hold stays withdrawable whatever we do with the menu.