Temenos core banking upgrades and Temenos SaaS
We upgrade Temenos Transact (the product used to be called T24) and help banks decide on Temenos SaaS. First we trace every local development to the transactions and reports that call it, and retire the unused ones. What's left maps to base functionality or extensions. We automate regression on balances, interest and accounting entries, then rehearse close of business and the cut-over.
- 01Local development trace
- 02Target choice
- 03Rebuild and reduce custom code
- 04Automated regression
- 05COB rehearsal and cut-over
The story
Told without the client's name or anything that could identify them.
A regional bank ran an old self-hosted Transact release carrying local developments written over many years, so every upgrade estimate read like a rewrite. Close of business ran long, regression meant operations staff checking balances by hand, and the bank wanted Temenos features its release didn't have. We traced each local development to the transactions and reports that used it, from production activity, and retired the code nothing called. The bank compared a self-hosted upgrade with Temenos SaaS while we mapped the remaining code to base functionality or extensions and automated regression on balances, interest and accounting entries. Close of business was rehearsed on production volumes until it fit the window, and cut-over ran with a tested rollback point.
why it was urgentTemenos SaaS runs on Microsoft Azure and AWS, and Temenos says it handles operations and support, scaling, annual updates and upgrades. On 7 May 2026 it announced AI Agents and Copilots across its core and digital banking products, plus Conversational Studio. For a bank on an old self-hosted release with a lot of local code, the gap widens every year.
- openLocal developments written over many years make every Transact upgrade look like a rewrite.
- recurringClose of business runs long and nobody wants to touch the jobs that cause it.
- blockedRegression is a manual check of balances and statements by operations staff.
- openThe business keeps asking for Temenos's newer AI and digital features, and your release doesn't have them.
The estate, before and after
Before: an old Transact release weighed down by local code
An old self-hosted Transact release sat at the center, with channels and payment systems calling it directly. Local developments had piled up inside the core for years, COB ran past its window, and regression was a manual check of balances and statements.
Read the diagram as text
- Digital and branch channels → Transact, old release: direct calls
- Payments and cards → Transact, old release: direct interface
- Transact, old release → Local developments: custom routines
- Transact, old release → Close of business: nightly batch
- Close of business → Statements and GL feeds: statements · GL
- Manual regression → Statements and GL feeds: spot checks
After: a current Transact release with supported extensions
We connected channels and payments to a current Transact release, self-hosted or on Temenos SaaS, over retested interfaces. What's left of the custom logic runs as supported extensions. An automated regression pack checks balances and accounting before every change.
Read the diagram as text
- Digital and branch channels → Transact, current release: retested interface
- Payments and cards → Transact, current release: retested interface
- Supported extensions → Transact, current release: extension points
- Transact, current release → Close of business: nightly batch
- Close of business → Statements and GL feeds: statements · GL
- Automated regression pack → Transact, current release: version compare
- Automated regression pack → Statements and GL feeds: break report
How we run it, phase by phase.
5 phases take you from Temenos Transact or T24 (self-hosted) to Current Transact release or Temenos SaaS. Each one ends with something you can check before the next starts. As you scroll, the blocks show the estate moving across.
- phase 01
Local development trace
We go by production activity. Every local development is linked to the versions, transactions, routines and reports that actually call it. Code with no callers is marked for retirement.
- phase 02
Target choice
Before committing, compare a self-hosted upgrade with Temenos SaaS. Look at regulatory hosting rules, integration changes and extension options, and be realistic about how many annual updates your team can absorb.
- phase 03
Rebuild and reduce custom code
Map remaining local developments to base functionality in the target release where it exists, and rebuild the rest as supported extensions.
- phase 04
Automated regression
Compare balances, accruals, interest, charges and accounting entries between versions on a copy of production, and review only the breaks.
- phase 05
COB rehearsal and cut-over
Rehearse close of business on production volumes until it fits the window, then cut over at a weekend or month end with a tested rollback.
What the client got
What changed for the client once the work was done. Described, not scored: we don't publish client figures.
- result 01
Every local development has a recorded decision
We linked each one to the versions, transactions, routines and reports that call it, and marked it to retire, map to base functionality or rebuild as a supported extension.
- result 02
Regression runs automatically on a copy of production
The regression compares balances, accruals, interest, charges and accounting entries across versions. Staff review the breaks. The statement-by-statement manual check is gone.
- result 03
Close of business fits its window
Rehearsals on production volumes produced real COB timings, and the cut-over plan and rollback point were set from those timings.
- result 04
The hosting choice rests on a written comparison
Self-hosted upgrade and Temenos SaaS were compared on regulatory hosting rules, integration changes, extension options and the annual update cadence the bank can absorb.
- result 05
Payments, cards and channels were retested
We wrote a retest plan for every interface that calls Transact directly, including the changes some of them needed for SaaS hosting.
Risks we plan for
-
Carrying dead code forward
A local development with no recent activity still has to be tested. Retire it before the upgrade, and that's testing time you don't spend.
-
Close of business overrunning
A COB that overruns delays branch opening and online banking. Rehearse it on production volumes and plan from the real timings.
-
Interfaces to payments and channels
Payments, cards and digital channels tend to call Transact directly. We retest every interface. Some of them will need changes for SaaS hosting.
-
Regulatory approval for SaaS
A hosted core usually needs outsourcing approval and an exit plan. Start that work in parallel on day one.
Where AI helps, and where it needs guardrails
Temenos now has AI Agents, Copilot for Workbench for extension work, Copilot for Core for branch staff and an FCM AI Agent for instant payments. Start the copilots on read-only tasks. If an external agent or MCP server needs Transact data, give it its own identity with narrow API scopes, rate limits and audit logs, and make a person approve anything that posts a transaction.
forward deployed engineers →What you're left with
We write these for your setup, and they're working documents. Your team should be able to keep things running from them long after we've gone.
- document01
Local development trace with retire, map or rebuild decisions
yours to keep - document02
Self-hosted upgrade versus Temenos SaaS comparison
yours to keep - tests03
Automated regression pack for balances, interest and accounting
yours to keep - tests04
Close-of-business timings from production-volume rehearsals
yours to keep - tests05
Interface retest plan for payments, cards and channels
yours to keep - runbook06
Cut-over runbook with rollback point
yours to keep
Platforms and services on this move
Certified engineers, wherever you need them.
Some clients want a project team, some want a couple of engineers on theirs. Either works. Onsite, nearshore or offshore, with handovers across time zones that keep things moving.
Onsite
Engineers at your sites in the US
Nearshore
Overlapping hours with US teams
Offshore
Overnight progress on your backlog
All time zones
Coverage handed over across time zones
01Is T24 the same as Temenos Transact?
Yes. Temenos renamed T24 to Temenos Transact. Older documentation and job titles still use T24, and the skills carry over.
02Should we upgrade or move to Temenos SaaS?
It depends on your regulator's view of hosted core banking, how much local code you're carrying and whether you can accept annual updates. We compare the two against your own estate.
03What drives the cost of a Transact upgrade?
Mostly the number of local developments still in use, the interfaces to payments and channels, and how regression is done. Banks that trace and retire unused code first usually have a shorter test phase.
04Can you staff Temenos developers?
Yes. We place Transact developers, functional consultants and test automation engineers, onsite, nearshore or offshore, on contract, contract-to-hire or permanent terms.
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read the case studyAD FS federation to Entra ID authentication
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read the case study
Apache Airflow 2 to Airflow 3
Upgrading self-managed Apache Airflow 2, now past end of life, to Airflow 3, and fixing removed features, auth and scheduling changes before DAGs move.
read the case study5766fbe4 - 01Temenos: Temenos SaaStemenos.com ↗
- 02Temenos: Temenos launches embedded AI capabilities (7 May 2026)temenos.com ↗
- 03Temenos: T24 is now Temenos Transacttemenos.com ↗
Planning this move?
A 30-minute working session with a senior engineer. No slides.
- The platform and the version you're on
- Where you need to get to, and by when
- What's custom: rules, plugins, integrations
- Any audit finding or deadline driving it