Banking Software Development Services
Banks and credit unions get the digital layer on top of the core they run. Neobanks get the app and the ledger their sponsor bank requires. Our banking software development services cover mobile and online banking, onboarding, payments and disputes, and the phased move off an old core. We scope the work in two to three weeks, with the engineers who will build it.
Custom Banking Software Development Around the Core You Have
Plus8Soft is a banking software development company for banks, credit unions, neobanks and fintechs on a sponsor bank. Our software connects to the core system (the bank’s record of accounts and postings) or your sponsor bank, the card processor and the payment rails (ACH, wires, FedNow, RTP). Accounts and funds stay at your bank or sponsor bank; we are not a bank or a money transmitter.
In the 2023 household survey by the US deposit insurer, 48.3% of banked households named mobile banking as their primary way in. A package that does not fit your products or onboarding rules shows up first in the mobile app. Custom banking software development pays off then; where a package fits, we integrate it. Onboarding is where compliance enters the build, and our guide to client onboarding and compliance software covers it.
That is why scoping starts with the connections between the app and the core or sponsor bank. Scoping takes two to three weeks at a fixed fee with the engineers who will build the system, and you keep the scoping documents. The build runs in increments of two to four weeks, each tested on its own. Customers get the first release when scoping says it is ready. After launch, the build team stays on under a support plan agreed in scoping. When the core itself is the project, scoping adds a phase plan that the estimate follows.
Banking App Development and the Systems Around It
We scope and build six kinds of banking software, all connected to the core, the card processor and the rails you already run on.
01
Mobile Banking App Development
Mobile banking app development for iOS and Android on one integration layer (a single back end that talks to the core and vendors). The app shows balances, history, transfers and bill pay, check deposit, card controls, alerts, secure messages. Pending items show as the core will settle them, which removes one reason to call support.
01
Mobile banking app development for iOS and Android on one integration layer (a single back end that talks to the core and vendors). The app shows balances, history, transfers and bill pay, check deposit, card controls, alerts, secure messages. Pending items show as the core will settle them, which removes one reason to call support.
02
Digital Onboarding and Account Opening
Account opening in the app or the browser with identity verification, document capture and the screening steps your policy requires. A clean applicant finishes without staff involvement; an application that needs review lands in a queue with the evidence attached.
02
Account opening in the app or the browser with identity verification, document capture and the screening steps your policy requires. A clean applicant finishes without staff involvement; an application that needs review lands in a queue with the evidence attached.
03
Online Banking and Business Servicing
Online banking with multi-user access, roles and approval limits, payment and payroll files, statements and reporting. Your staff get a console that shows each account as the customer sees it. Staff can open a customer's view to help with a request without asking for screenshots.
03
Online banking with multi-user access, roles and approval limits, payment and payroll files, statements and reporting. Your staff get a console that shows each account as the customer sees it. Staff can open a customer's view to help with a request without asking for screenshots.
04
Neobank App Development
A neobank runs under its sponsor bank's license, so we start from the ledger and reporting the bank requires, then build the app on top. The bank can be direct or reached through a banking-as-a-service platform (a provider selling a partner bank's services by API).
04
A neobank runs under its sponsor bank's license, so we start from the ledger and reporting the bank requires, then build the app on top. The bank can be direct or reached through a banking-as-a-service platform (a provider selling a partner bank's services by API).
05
Core Banking Modernization
Core banking modernization in phases. Products and customers move in planned groups, and each phase has its own go-live and rollback plan. In the parallel-core option, the old and the new core run side by side until the last account moves.
05
Core banking modernization in phases. Products and customers move in planned groups, and each phase has its own go-live and rollback plan. In the parallel-core option, the old and the new core run side by side until the last account moves.
06
Payments and Disputes
Instant payments over FedNow or RTP, plus ACH and wires through your bank's rails. A dispute flow records the claim, posts provisional credit (a temporary refund while the case is open) on the schedule your policy sets, and tracks the case to closure.
06
Instant payments over FedNow or RTP, plus ACH and wires through your bank's rails. A dispute flow records the claim, posts provisional credit (a temporary refund while the case is open) on the schedule your policy sets, and tracks the case to closure.
What Digital Banking Software Development Includes
Scoping and the System-of-Record Map
We trace the connections between your channels, your core or sponsor bank and external systems, and the data moving over them. We sit with operations and compliance leads to learn how money, data and decisions move today, and what you want the first release to cover. The scoping documents are a system map (the system of record for each balance) and an integration list with an owner for each connection. They also include a data model, a risk list, a build estimate and a support plan.
Core and Vendor Integration Layer
The integration layer is the single back end behind the mobile app, online banking and the staff console. It holds adapters (one connector per provider or system) for your core or sponsor bank and for the processor, rails, identity and fraud vendors. A posting carries an idempotency key (a unique ID that makes a repeated request count once) where the core supports it. Memo posting (the core's intraday pending entries) is modeled so pending items reach the app before the core settles them.
Identity, Authentication and Onboarding Engineering
We default to passkeys for login and step-up authentication (a second check before a risky action). Your risk assessment can add or relax factors, with SMS as a fallback where your risk assessment permits it. Onboarding orchestrates document capture, liveness (a check that a live person is present), and device and bot signals. It runs the identity checks your compliance team specifies, with each decision and its evidence logged. We build transfer rules, with limits your risk team sets, such as velocity limits (caps on how much and how often money moves).
Ledgers for Sponsor-Bank and Embedded Models
For accounts held at a sponsor bank, we build a double-entry ledger (each amount is recorded as a matching debit and credit). It has an append-only event log (entries are added and not edited) and keeps a balance for each end customer, with holds and pending items. A daily reconciliation (matching your records against the bank's) opens a ticket on each break (a mismatch found in reconciliation). The ledger records balances, and payment instructions go to the bank through the integration layer; reporting gives the bank the view it specifies.
Security Controls and Examiner Evidence
Controls include role-based access, secrets management (keeping passwords and keys out of code) and encryption in transit and at rest. Audit logs cover actions that touch customer data or money. Card numbers stay with the processor. The app and the staff console work with tokens (stand-ins for card numbers), which narrows the PCI DSS (card industry security standard) footprint your assessor confirms. Change control is documented, and the evidence your compliance team hands to examiners is kept with the system and updated with each release.
Testing and Accessibility
Automated tests cover each money flow, including transfers, holds, disputes and reversals. They run against the core sandbox (the vendor's test copy of the core) or the sponsor bank's test environment. Load tests cover payday and month-end peaks. Web and mobile are built to WCAG 2.1 AA (a widely used accessibility standard) and tested with screen readers and automated checks before each release. A third-party accessibility audit is scoped when your policy requires one.
We trace the connections between your channels, your core or sponsor bank and external systems, and the data moving over them. We sit with operations and compliance leads to learn how money, data and decisions move today, and what you want the first release to cover. The scoping documents are a system map (the system of record for each balance) and an integration list with an owner for each connection. They also include a data model, a risk list, a build estimate and a support plan.
Our Case Studies
Hola Salud
Hola Salud
Digital healthcare platform for Mexico.
We built a complete healthcare ecosystem, including a patient app, a doctor’s portal, and an admin backend, with self-registration, appointment booking, medical records, and integrated Stripe and Oxxo payments.
Environmental AI
Environmental AI
Environmental compliance automation.
We built a RAG-based system that automates environmental assessment documents and regulatory templates, cutting preparation time by up to 90%.
Revvel
Revvel
AI-powered women’s health platform.
We developed an AI platform that turns elite health experts into digital twins and reviews years of patient data in under 60 seconds, delivering risk assessments up to 10x faster and cutting time-to-care from days to minutes.
InnerPeak.AI
InnerPeak.AI
Student mental wellness platform.
We developed a comprehensive web and mobile application that provides students and teachers with 24/7 personalized support and engaging resilience training to build essential life skills.
Hello, We Hire
Hello, We Hire
AI-driven recruitment automation platform.
We built an AI-powered recruitment system with automated pre-screening, real-time skills evaluation, and multi-stage verification that speeds up hiring by 94%.
Hola Salud
Hola Salud
Digital healthcare platform for Mexico.
We built a complete healthcare ecosystem, including a patient app, a doctor’s portal, and an admin backend, with self-registration, appointment booking, medical records, and integrated Stripe and Oxxo payments.
Environmental AI
Environmental AI
Environmental compliance automation.
We built a RAG-based system that automates environmental assessment documents and regulatory templates, cutting preparation time by up to 90%.
Revvel
Revvel
AI-powered women’s health platform.
We developed an AI platform that turns elite health experts into digital twins and reviews years of patient data in under 60 seconds, delivering risk assessments up to 10x faster and cutting time-to-care from days to minutes.
InnerPeak.AI
InnerPeak.AI
Student mental wellness platform.
We developed a comprehensive web and mobile application that provides students and teachers with 24/7 personalized support and engaging resilience training to build essential life skills.
Hello, We Hire
Hello, We Hire
AI-driven recruitment automation platform.
We built an AI-powered recruitment system with automated pre-screening, real-time skills evaluation, and multi-stage verification that speeds up hiring by 94%.
Flexible Developer Hiring Model
Your priorities define the way we work together — from how much control you want to the level of flexibility your project demands.
Team Augmentation
Quickly scale your workforce with skilled developers who integrate seamlessly into your in-house team, filling talent gaps and boosting productivity.
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Dedicated Development Team
A whole, cross-functional team working exclusively on your project, providing end-to-end development, management, and long-term support.
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Software Development Outsourcing
Delegate your entire project to our specialists and focus on business growth, while we handle development, delivery, and quality.
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Why Plus8Soft?
01
Experience
Multiplied by AI
Multiplied by AI
We blend deep engineering expertise with cutting-edge AI acceleration. By integrating intelligent tools into our workflow, we don't just write code—we engineer solutions faster and with higher precision.
02
Business-First
Transparency
Transparency
We look beyond the ticket. Our team operates with hyper-transparency, treating your budget and goals as our own. We align technical decisions with your business strategy to create real, measurable value.
03
Committed to
Overdelivery
Overdelivery
Meeting requirements is our baseline; exceeding them is our culture. Whether it's optimizing performance, refining UX, or anticipating future scalability, we consistently go the extra mile.
Banking Software Development FAQ
What does a banking software development company build that our core vendor does not?
Your core vendor runs the system of record: accounts, postings, interest and the general ledger, often with a digital banking package on top. We build what the package does not fit: your own mobile and online banking, onboarding with your rules, and servicing tools for your staff. We also build the integration layer that connects them to the core and the rails. We do not replace the core unless that is the project. We are not a bank, a program manager or a money transmitter. Accounts and funds sit at your bank or your sponsor bank, and the software we deliver runs under your third-party risk program.
Do you do mobile banking app development on an existing core?
Yes, and that is the default. The app talks to an integration layer, and the layer talks to the core's API, batch files or message queue. Your release calendar is then your own within the interface versions the core supports. The first release is usually a single flow on the existing core, most often account opening or card controls.
Can you work with Fiserv, Jack Henry, FIS or Temenos?
n a 2024 Kansas City Fed briefing citing 2022 industry survey data, Fiserv, Jack Henry and FIS together served more than 70% of the banks surveyed. A US bank project usually starts from one of the three. We work through the interface your core vendor publishes and the access your bank already holds. Access runs through the vendor's program (Fiserv Developer Studio, Jack Henry's Vendor Integration Program) and your own contract with the vendor, and scoping confirms both before the estimate.
How do you approach core banking modernization?
We do it in phases. The Kansas City Fed lists three options. The first is full replacement, which it calls the most risky and expensive and often a last resort. The second is component-based replacement. The third wraps the legacy core with a parallel core connected through APIs. We scope the second and third. Products and customers move in planned groups, and both cores stay live until the last account migrates. Each phase has its own go-live and rollback plan. The plan includes the incumbent's contract terms, deconversion and the new vendor's conversion team, because those set the calendar more than the code does.
How do you handle a bank's vendor due diligence and examiner questions?
Banks review software vendors as third parties under the interagency guidance of 2023, and examiners review development and change control under the FFIEC IT Examination Handbook. We expect the questionnaire about us as a vendor and answer it before scoping. It covers where our engineers work, which access to customer data they hold and under whose control, and the attestations and insurance you ask about. Development and testing run on synthetic data, and production data is reached only through access your bank issues, logged, and revoked at handover.
For the systems we deliver, we build the evidence in from the start. That means an architecture and data flow document, requirements traced to tests, documented change control, access reviews, and penetration test results where a test is in the scope. What applies is for your compliance team and examiners to decide. We provide the evidence.
What authentication do you build into a banking app?
Login and step-up authentication are chosen by your risk assessment, as the 2021 FFIEC authentication guidance expects. Passkeys and app-based factors are the default, with SMS as a fallback where your risk assessment allows it, plus device binding and session rules by transaction risk. NYDFS Part 500, as amended, requires multi-factor authentication for any individual accessing a covered entity's information systems from November 2025, with a narrower rule for limited-exemption entities. Whether and how it applies to you is for your compliance team or counsel to confirm. We build the app, the admin console and the vendor portals to that standard where your compliance team confirms it applies.
What will our sponsor bank require from a neobank app?
Each sponsor bank sets its requirements in the program agreement. Most center on four things: a ledger with a balance for each end customer, daily reconciliation against the bank's records, per-program reporting, and the deposit insurance disclosures the bank specifies. Since 2024, regulators have brought enforcement actions against several sponsor banks over their fintech partnerships, and the FDIC has proposed daily recordkeeping for custodial accounts. Neobank app development with us starts from that ledger and that reporting, because program agreements usually name both as launch conditions. Your sponsor bank's compliance team sets the final list.
How long until our first release with Plus8Soft?
Scoping takes two to three weeks. A mobile banking MVP is planned at four to six months, and a first release of a single flow on an existing core is shorter. Both are planning estimates confirmed in the scope. A first release is usually a team of four to six: a lead, two to three engineers, QA and a designer part time. After that, we release in increments of two to four weeks, each one tested on its own. A phased core modernization runs twelve to eighteen months in our planning, with a go-live for each phase and the vendors' conversion calendars setting the floor.
How do you price a banking software project?
Scoping is quoted as a fixed fee before it starts. The build estimate depends on the core and the number of integrations, the journeys in the first release, and how much onboarding, ledger and servicing tooling you already have. The estimate is confirmed before development starts.
Which technologies do you use?
Back end: Node.js with NestJS, Go and PHP, with PostgreSQL and a message queue for transaction events. Front end: React, TypeScript and Next.js for web, React Native and Swift for mobile. Infrastructure runs on Docker and Kubernetes on AWS, and we work in your stack and your cloud when you already have one or the bank's policy requires it.
Who owns the code?
The code we write for you is yours. We work under an NDA, with access limited to the repositories and environments the project needs, and hand over documentation and credentials when the engagement ends.
How do you handle fraud in onboarding and transfers?
In the 2026 Javelin identity fraud study, new-account fraud cost $7 billion in 2025. In Alloy's 2026 survey, 71% of fraud and risk leaders saw fraud most often in online and mobile banking. Onboarding combines document capture, liveness, device and bot signals and the identity checks your compliance team specifies, and sends the doubtful cases to a review queue with the evidence attached. Transfers run through velocity rules and step-up authentication by amount and risk, with the rules in your team's hands through an admin screen. We build the flow and the tooling; your risk team sets the thresholds.
What do you ask before quoting?
Five things. Which core and version you run, and which digital banking package sits on it today and under what contract. Which journey loses the most customers or staff time. Where staff correct records by hand. Which vendor sandbox and interface access the bank already holds. And who on your side owns each external connection. The answers shape the scope, and the estimate follows the scope.
