Library

Transaction enrichment library for Express

Use TxnKit as a transaction enrichment API from Express. This page shows the safe request shape, a short code snippet, and the boundary for keeping sensitive data out of the integration.

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Target intent

Express applications that need a backend transaction enrichment route.

TxnKit should be called from the Express server, not from browser code with a secret key.

Raw descriptor

SQ *JOES COFFEE 0421 TORONTO

Short Express API snippet

app.post("/api/enrich-transaction", async (req, res) => {
  const upstream = await fetch("https://api.txnkit.dev/v1/enrich", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.TXNKIT_API_KEY}`,
      "Content-Type": "application/json"
    },
    body: JSON.stringify({ raw_description: req.body.raw_description, country: "CA" })
  });

  res.status(upstream.status).json(await upstream.json());
});

Keep API keys out of browser bundles. For frontend stacks, call a backend route or serverless function that owns the TxnKit request.

API-shaped output

{
  "input": {
    "descriptor": "SQ *JOES COFFEE 0421 TORONTO",
    "country": "CA"
  },
  "output": {
    "merchant_name": "Joes Coffee",
    "category": "Coffee shop",
    "confidence": "medium",
    "signals": [
      "processor_pattern",
      "merchant_alias",
      "category_hint"
    ],
    "warnings": [
      "review_low_confidence_matches_before_showing_logo"
    ],
    "logos": []
  }
}

Low-confidence results should keep fallback labels and warnings visible instead of forcing a guessed logo or website.

When to use

  • You are building in Express and need one-descriptor merchant cleanup through an HTTP API.
  • Your app can keep the TxnKit API key on the server side or inside a trusted serverless function.
  • You need merchant display names, categories, confidence, signals, warnings, and logo-ready metadata.

When not to use

  • TxnKit should be called from the Express server, not from browser code with a secret key.
  • Do not use TxnKit to process card numbers, account numbers, full statements, bank credentials, emails, phone numbers, addresses, customer names, or customer PII.
  • Do not use TxnKit when the product requirement is guaranteed merchant identity, every-merchant resolution, or contracted uptime terms.

Proof surfaces

The public contract is POST /v1/enrich, backed by the OpenAPI file, benchmark examples, privacy rules, and deterministic request-path tests.

OpenAPI · Benchmark · Security · Pricing

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