Open Banking Treasury App Cost in London (2026)

The verdict in three sentences

For a group of 12 companies with 25 accounts across 6 banks, a custom treasury app connected to an Open Banking aggregator costs GBP 30,000 to 70,000 to build and GBP 250 to 1,300 a month in API access. It ships in 3 to 5 months and saves the treasurer 1 to 2 working days per week currently spent downloading statements into a spreadsheet. Against a market TMS at GBP 17,000 to 50,000 a year, custom pays back in 2 to 3 years when your needs are focused: consolidated position, 13-week forecast, automatic reconciliation.

Aggregator, Open Banking or direct bank connections

UK Open Banking, overseen by the FCA, gives regulated providers read access to business accounts. Most mid-sized groups do not connect bank by bank: they use an authorised aggregator (TrueLayer, Yapily, Plaid or similar) that maintains the 6 connections, the 90-day consent renewals and each bank's API quirks. Bacs and SWIFT files remain relevant for bulk payments and detailed statements.

For 25 accounts, the usual mix is Open Banking for the morning position plus host-to-host files for detailed statements and bulk payments.

What the GBP 30,000 to 70,000 covers

The high end means two-way ERP integration and intercompany loans; the low end, read-only accounts with an accounting export.

Custom versus a market TMS

A TMS (Kyriba or lighter mid-market tools) brings FX hedging, cash pooling and debt management. A 12-entity UK group will leave much of it unused. Over 5 years, a TMS at GBP 30,000 a year costs GBP 150,000, versus around GBP 50,000 build plus GBP 46,000 of aggregator and maintenance for custom. Custom loses the edge once you need multiple currencies, hedging and physical cash pooling. See our custom web applications page.

A realistic timeline runs in four steps. Weeks 1 to 3: scoping with the CFO and treasurer, mapping each of the 25 accounts to an entity and a cost code, and signing the aggregator contract. Weeks 4 to 12: build of the connections, consolidated position and categorisation rules, with a weekly demo on real data from two pilot entities. Weeks 13 to 16: reconciliation and forecast, then three weeks of parallel running where the spreadsheet and the app must agree to the penny. Weeks 17 to 20: rollout to the remaining entities, training and handover. Groups that skip the parallel run usually lose a month later chasing discrepancies.

Mini case study

Sarah, group treasurer of a London distribution business, spends 1 h 30 each morning logging into 6 banks and updating her spreadsheet, plus 3 hours a week on reconciliation: 10.5 hours a week. With the app, the position is ready at 8 am and automatic matching clears 85 % of lines, leaving 2 hours. Savings: 8.5 hours a week, about 390 hours a year. At GBP 65 per loaded hour, that is GBP 25,350 a year. Spotting GBP 350,000 of surplus earlier and placing it at 4 % adds GBP 14,000. Against a GBP 50,000 build and GBP 8,000 of yearly running costs, payback comes in under 18 months.

FAQ

Is bank data secure?

The aggregator is FCA authorised with read-only access. The app adds MFA, encryption and an audit log, with UK hosting at roughly GBP 120 to 350 a month.

What if a bank API goes down?

It happens 2 to 5 times a year per bank. The app flags it and falls back to the last statement file while the 5 other banks keep updating.

Can we make payments from the app?

Yes, through Open Banking payment initiation or bank files, with dual approval. Allow GBP 7,000 to 13,000 extra.

How reliable is the 13-week forecast?

It draws on ERP due dates and history. After 3 months of calibration, a 5 to 10 % variance at week 4 is a common result.

How fast can we start?

Three to five months overall, including 3 weeks of scoping and 3 weeks of parallel running with the old spreadsheet.

Let's scope your project. List your banks, entities and ERP and we will scope connections, reconciliation and forecasting with a go-live plan within one quarter. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.