FX fee auditor for corporate card programs

The moment a finance manager realizes they have a problem is when they're reconciling last month's international travel expenses and they can't tell whether the $340 in 'fees' was the card network's spread, the expense tool's markup, or merchant-side conversion — and they have no way to find out without calling three different support lines.

This gap persists because the incumbent expense tools have every incentive to obscure FX markup. The spread between the interbank rate and what a cardholder pays is a significant revenue line for card issuers and expense software vendors alike. Exposing that spread clearly would invite users to compare and complain. The buyer (CFO or finance director) signs the contract, but the user (the traveling employee) absorbs the pain silently — so nobody complains loudly enough to move the needle on a procurement decision.

What's missing isn't a better exchange rate — it's a way to audit what rate you actually received, per transaction, versus what you should have paid. Right now, a company spending $500K/year on international expenses gets a single blended FX line with no breakdown by processor, card type, or merchant category. The Saudi Airlines split-posting problem is a symptom of exactly this: when a charge posts in two parts, the FX conversion may apply differently to each part, and no current tool surfaces that discrepancy or flags it for review.

This is a business and not a feature because the audit has to happen every month, every cycle. Each new batch of international expenses creates new exposure. A one-time audit would find the problem; a recurring service is what prevents it from silently compounding. For a company running $1M in annual international spend with a 1.5% hidden FX spread they're unaware of, that's $15,000/year in avoidable cost — more than enough to justify a recurring subscription to something that catches it.

What to build

Ingest corporate card transaction exports (CSV or direct API), compare the posted conversion rate on each foreign-currency charge against the published interbank rate for that currency pair on that date, and generate a monthly report showing total FX overage by card, by employee, and by merchant category — with flagged anomalies like split-posted charges where conversion rates diverged between the two parts.

Where to start

Start with companies already exporting data from Airwallex or Amex GBT, where the CSV format is known and the FX fee complaints are loudest — build the first integration around that specific export schema before expanding to other card programs.

The hard part

Getting clean, machine-readable transaction data that includes the original foreign currency amount, the posted USD amount, and the transaction date — most card export formats either strip the foreign currency detail or aggregate it in ways that make per-transaction rate reconstruction unreliable.

How it makes money

Monthly subscription charged to the finance team, scaled by volume of international transactions analyzed — e.g., flat fee up to 500 foreign-currency transactions/month, then per-transaction above that.