Transaction categorisation API
An API that sorts raw bank transactions into categories.
A transaction categorisation API takes raw bank transactions — a description, an amount, a date — and returns each one sorted into a category such as groceries, rent or software, often with a cleaned-up merchant name. Transactions pushed through 2Fin’s Integrations API go through the same categorisation as every other transaction, and on AUTO+ the result comes back to your endpoint as a signed webhook.
Most categorisation combines rules, a merchant database and a learned model, and the useful differences are in the details: whether a category describes spending or a tax treatment, whether corrections teach the system, and whether the reasoning is visible. Fin applies your rules first, then patterns learned from your corrections, then its intelligent categorisation.
Worked example
You push "SQ *BLUE BOTTLE 0423", -6.40 USD, 2026-07-05 to POST /api/integrations/v1/transactions with an Idempotency-Key. Fin checks your rules, then your past corrections, then categorises it from the merchant; on AUTO+ your endpoint then receives a transaction.categorized event signed in X-AI2Fin-Signature, with a delivery ID to de-duplicate retries.
Common mistake
Treating the category as the tax answer. A category says what the money went on; whether it is deductible, and how GST or VAT applies, is a separate decision that depends on who spent it and why — which is why 2Fin records both on each transaction.
Figures last checked . General information, not tax advice.
Related terms
Open banking connector
Software that moves bank transaction data between systems on published standards.
Banking-as-a-Service (BaaS)
A licensed bank offering accounts, cards and payments to other companies through APIs.
Tax treatment (GST treatment)
The code that decides which activity-statement label a transaction feeds.
ISO 20022
The international standard for financial messages — payments, statements and more.
← Back to the full glossary.
Questions about this term
Transaction categorisation API: common questions
- What is the difference between transaction categorisation and transaction enrichment?
- Categorisation assigns each transaction to a category. Enrichment is the wider job of adding information to a raw transaction — a clean merchant name, a logo, a location, a recurring-payment flag — and categorisation is usually one part of it.
- How do I get transactions categorised by 2Fin through the API?
- Push each one to POST /api/integrations/v1/transactions with an OAuth token your customer approved and an Idempotency-Key. Fin categorises it with the customer’s own rules and learned patterns, and on AUTO+ a signed transaction.categorized webhook tells your endpoint the result.
- Can the categories follow my own chart of accounts?
- In 2Fin, yes. Customers can build their own category sets and switch between them on ELITE+, write rules that send a merchant to a category on Premium and up, and on ELITE+ the Xero and QuickBooks Online connectors (in beta) map Fin’s categories onto the ledger’s chart of accounts.
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