Bring your own provider

Sync banks through your own SimpleFIN or Lunch Flow Personal API account.

Written By Pedro

Last updated 6 days ago

Bring your own provider lets you sync banks through a provider account you pay for and control directly. Zerosum stores the credential securely and runs the same review, matching, and duplicate prevention as the managed options. Today this covers SimpleFIN and the Lunch Flow Personal API.

How it works

  • You own the provider account. You sign up with the provider, add your banks there, and pay them directly. Zerosum never sees your banking password.

  • Works alongside the managed options. You can add SimpleFIN or the Lunch Flow Personal API on top of Plaid or Lunch Flow Platform.

  • Zerosum stores one credential. You paste a token or API key once. Zerosum encrypts it at rest and never shows it again.

  • Same safe import. Imported transactions go through the same register review, matching, and duplicate prevention as Plaid and managed Lunch Flow. Nothing approved or reconciled is silently overwritten.

  • You control linking. Connecting a provider does not add every account to your budget. You link each provider account to a Zerosum account yourself.

ℹ️ Bring your own provider is included with Plus and with Pro, including your Pro trial. In a shared budget, only the owner can connect and link accounts.

Connect SimpleFIN

SimpleFIN gives Zerosum a read-only Setup Token for your accounts.

  1. In Zerosum, open Bank Sync and choose Connect SimpleFIN.

  2. Select Open SimpleFIN Bridge, add your banks there, and generate a one-time Setup Token.

  3. Paste the token back in Zerosum. The token can be claimed only once, and Zerosum encrypts the resulting access credential and never shows it again.

  4. Your accounts appear in Zerosum. Link each one to a new or existing Zerosum account. If you add banks later, choose Refresh accounts.

Connect the Lunch Flow Personal API

The Personal API uses your own Lunch Flow account and API key, so you manage your bank connections and billing directly in Lunch Flow.

  1. Create a Lunch Flow account and connect your banks there.

  2. In Lunch Flow, add the API destination and select the accounts you want to share with it. See Lunch Flow’s Personal API overview if you get stuck.

  3. Copy the API key for that destination.

  4. In Zerosum, open Bank Sync, choose Connect Lunch Flow API, and paste the key.

  5. Link each account to a new or existing Zerosum account.

Already using Lunch Flow through Pro?

The Personal API uses your own Lunch Flow account. If you already use the managed Lunch Flow Platform option, that is tied to the Lunch Flow account for that email, so create a separate Lunch Flow account under a different email for your Personal API key. Add your banks to that account, choose the API destination, and copy the key.

  • Unlink one account returns it to manual mode and stops syncing. The account and its transactions stay.

  • Disconnect SimpleFIN or Disconnect Lunch Flow API deletes the stored credential and returns every linked account to manual mode. Existing transactions stay. Your account with the provider itself is not deleted, so manage or close it directly with SimpleFIN or Lunch Flow.

Troubleshooting

  • Your provider reports a warning. Messages from SimpleFIN appear on the connection card in Bank Sync and usually say what to do, like reauthorizing a bank in SimpleFIN Bridge. For Lunch Flow, fix connection issues in your Lunch Flow account.

  • Your first import could not finish. Zerosum links the account anyway and asks for the cleared balance your bank shows. That becomes the starting balance, and importing begins from today onwards. If a transaction from earlier today imports and the balance already includes it, reject it in review to keep the balance correct.