plaid-fintech

What it does

Implements end-to-end Plaid fintech patterns focusing on Link token creation and exchange, transactions synchronization via a cursor-based incremental sync and webhook handling, ACH transfers using Auth with identity verification, and real-time balance checks. It provides endpoints and frontend integration for linking bank accounts, exchanging tokens, and triggering transaction updates, along with error handling for common Plaid webhook states and update modes.

How it works

• Link Token Creation and Exchange: Creates a link_token for Plaid Link, exchanges public_token for an access_token, stores the access_token securely, and triggers an initial transaction sync. Includes a frontend React component that fetches a link_token, opens Plaid, and exchanges the public_token on success.
• Transactions Sync: Uses a cursor-based loop to fetch incremental transactions via transactionsSync, stores added transactions, updates modified ones, and deletes removed ones. Saves the final cursor for subsequent runs. Webhook handler queues or triggers transaction sync on TRANSACTIONS webhook events such as SYNC_UPDATES_AVAILABLE, INITIAL_UPDATE, or HISTORICAL_UPDATE.
• Context sections indicate focus areas: initial bank linking, user onboarding, connecting accounts, and context around fetching transactions and history.
• Item Update and Errors: Creates update tokens, handles ITEM webhook codes (ERROR, PENDING_DISCONNECT, USER_PERMISSION_REVOKED), updates item status, and notifies users to reconnect when needed. A function enforces validation before API calls and throws if item is missing or in ERROR state.
• Auth for ACH Transfers: Uses Plaid Auth to fetch account and routing numbers, Identity to verify account ownership, matches stored user identity, and requires high confidence before transfers. Checks real-time balance before initiating ACH transfers and retrieves ACH numbers for transfer initiation.
• Real-Time Balance: Provides functions for real-time balance via accountsBalanceGet, and cached balance retrieval for display via accountsGet. Balances are used to validate funds before transfers.

When to use it

Use when you need a Plaid-based fintech integration that handles: user bank linking via Link, secure token exchange, incremental transaction syncing with webhook-based updates, ACH transfers with identity verification, and real-time balance checks.

What it can touch

• Tools: claude-code, codex, cursor
• Endpoints and components show interactions with Plaid API via PlaidApi and server routes like /api/plaid/create-link-token, /api/plaid/exchange-token, /api/plaid/webhooks, and frontend using usePlaidLink from 'react-plaid-link'.
• Data stores: Plaid items, transactions, and user identities, persisted with encrypted access tokens and updated transaction records.

Caveats

• Risk declared as critical in the skill metadata. The implementation includes handling of sensitive tokens (encrypted at rest) and financial data updates.
• The pattern relies on environment-provided Plaid environment, client IDs, and secrets, and assumes webhook verification patterns are implemented (verifyPlaidWebhook).
• Token lifetimes: Link tokens are described as short-lived and single-use; access tokens do not expire but may require updates when users change passwords.
• No outcomes promised; the skill describes concrete steps and code paths but does not guarantee success in all edge cases (e.g., webhook validation, network errors, or Plaid API changes).