Introducing Stash Core

By Stash Team
Last updated June 10, 2026

A money app is only as useful as the systems underneath it. If a customer taps their card, moves cash, earns a Stock-Back® reward, or checks an account balance, the experience should feel simple. Behind the scenes, it is not simple at all.

That is why Stash built Stash Core: a custom infrastructure platform designed to support banking, investing, money movement, rewards, customer service, and future product improvements from one stronger foundation.

Stash exists to bring guidance for everyone, not just people who already have a financial advisor. Core is a big part of that mission. It helps us move faster, operate with more control, and design products that connect everyday financial activity with long-term investing.

What is Stash Core?

Stash Core is the backend technology platform that powers key parts of the Stash experience, including:

• Ledgering for customer banking balances and general ledger activity

• ACH money movement infrastructure

• Debit card authorization decisioning

• ATM withdrawal support

• Stock-Back® reward processing

• Customer service and operations tooling

• Banking account integrations with Stride Bank, N.A., Member FDIC

Plain English version: Core is the plumbing, electrical panel, and control room behind the Stash app. Customers should not have to think about it. But when it works well, they feel the difference: clearer balances, faster support workflows, more reliable systems, and product experiences that fit together instead of feeling bolted on.

Why Stash built Core

Stash started with a simple belief: investing should not be locked behind jargon, high minimums, or expensive gatekeepers. Our customers can open personal brokerage accounts, earn Stock-Back® rewards with eligible debit purchases, access retirement investing tools, learn as they go, and use banking features through Stash plans starting at $3/month.

As Stash grew, our technology had to grow up too.

The old way of building financial products often looks like a patchwork: one vendor for one thing, another vendor for another, a third system for a customer service agent, and a fourth system for a ledger. That can work for a while. But it can also make it harder to innovate, harder to diagnose issues, and harder to create one connected customer experience.

Stash Core was built to solve that. It gives Stash more direct control over the parts of the experience that matter most: money movement, balances, card activity, rewards, and support.

Our point of view is simple: if we are going to put a financial advisor in your pocket, the infrastructure has to be strong enough to earn that trust.

What changed for customers

The first major product launch built on Stash Core was our refreshed banking experience, including the Stock-Back® Debit Mastercard® issued by Stride Bank, N.A., Member FDIC, pursuant to license by Mastercard.

The Stock-Back Card is one of the clearest examples of why Core matters. With eligible purchases, customers can earn up to 1% back in stock rewards. When you shop at a qualifying public company, you may earn a reward in that company’s stock. When the merchant does not have an eligible stock, the reward may be invested in a diversified fund option instead. Terms apply.

That may sound small. But it reflects a bigger idea: everyday spending can become a learning moment. A customer who buys groceries, gas, or coffee can begin to see the connection between companies they know and the market they are part of.

The point is not to make investing feel like a game. We are not building tools to encourage hot-stock chasing or day-trading culture. Stash is built around The Stash Way: invest for the long term, diversify, and invest consistently.

Core helps connect those ideas across the product.

A worked example: what happens after a debit purchase

Imagine a customer uses the Stock-Back® Debit Mastercard® for an eligible purchase.

Here is a simplified version of what Stash Core helps coordinate:

1. The merchant sends a card authorization request.

2. Stash Core helps evaluate the available balance in real time.

3. The transaction is approved or declined based on the account rules and available funds.

4. The ledger is updated so balances stay accurate.

5. The purchase is evaluated for Stock-Back® eligibility.

6. If eligible, a stock reward is calculated and routed to the customer’s investing experience.

7. Customer service systems receive the information agents need if the customer has a question.

To the customer, this is one tap of a card. To the platform, it is a chain of decisions that must happen accurately, quickly, and consistently.

That is why infrastructure matters. Good financial technology should make complex systems feel calm.

Building with purpose

The first question for Stash Core was not: What can we build?

It was: What problem are we solving for customers?

To answer that, Stash organized work into cross-functional squads. Product, engineering, design, operations, data science, compliance, customer experience, and other teams worked together around customer value streams.

That structure matters because financial products do not fail only because of bad code. They can fail because the design is confusing, the operations process is fragile, the customer support tool lacks context, or the product solves an internal problem instead of a customer problem.

Core forced us to build differently. The goal was not technology for technology’s sake. The goal was a platform that could help customers use Stash with more confidence and help internal teams support them better.

The three principles behind Stash Core

Stash Core was built around three operating principles: speed, reliability, and ownership.

Speed

Speed does not mean rushing money products into the world. In financial services, reckless speed is expensive for customers.

For Stash, speed means building with tools and processes that help teams ship useful improvements with discipline. We chose technologies that engineers could learn quickly and that are proven at scale. Go became a primary programming language for Core because it is widely used for infrastructure and distributed systems, including tools like Kubernetes and Terraform.

We also changed how product and engineering teams work together. Instead of one team writing requirements and another team passively executing them, squads shared responsibility for the outcome. Engineers, product managers, designers, operations specialists, and data partners all had a role in shaping what got built.

That reduces handoffs. It also reduces the chance that a feature looks good in a planning document but breaks down when a real customer uses it.

Reliability

Reliability is the non-negotiable part.

Stash Core gives Stash more control over real-time money movement infrastructure. That includes reading and writing NACHA files for ACH activity, making real-time decisions for debit card authorizations and ATM withdrawals, and maintaining ledger systems for customer banking balances and general ledger processes.

When a system touches customer balances, reliability is not an engineering preference. It is the product.

To support that, Stash added specialized reliability roles, including Site Reliability Engineers and Network Operations Center technicians. SREs work with squads while products are being built, not after something goes wrong. NOC teams help monitor systems and support incident response processes.

Core was also designed with resilience in mind, including multi-region infrastructure patterns and stronger testing practices. The goal is to catch problems earlier, recover faster, and reduce customer disruption when systems are under stress.

Ownership

Ownership means the people closest to the problem are trusted to solve it.

Stash Core gave squads clearer areas of responsibility. Instead of spreading one feature across too many teams and too many meetings, work could be organized around smaller groups with sharper accountability.

That has practical benefits:

• Fewer handoffs

• Faster decision-making

• Better technical context

• Clearer accountability when timelines shift

• More direct connection between product work and customer outcomes

This is not glamorous. It is how durable products get built.

Why Core matters in 2026

Since Stash Core launched in 2022, customer expectations for financial apps have only risen. People expect real-time answers, accurate balances, stronger fraud controls, easier support, and a product that helps them make progress instead of just showing a screen full of numbers.

At the same time, the need for accessible guidance is still real. Many people are trying to invest while also dealing with high living costs, uneven income, debt, and retirement questions. Traditional financial advice remains too expensive for many households.

Stash’s answer is not to tell people to figure everything out. It is to put investing tools, education, and guidance inside an app people can actually use.

Core supports that by making the product more connected. Banking activity can sit closer to investing education. Rewards can become part of a portfolio. Customer service agents can see better context. Product teams can build new features on a platform designed for Stash’s mission, not a generic vendor workflow.

Banking, investing, and FDIC insurance

Stash is not a bank. Banking services are provided by Stride Bank, N.A., Member FDIC.

As of 2026, the standard FDIC insurance amount is $250,000 per depositor, per insured bank, for each account ownership category. You can learn more about deposit insurance in our guide to the Federal Deposit Insurance Corporation.

Investment products are different. Securities held in a brokerage account are not FDIC insured, are not bank guaranteed, and may lose value. That distinction matters. Core connects banking and investing experiences inside Stash, but it does not erase the difference between deposits and investments.

What Stash Core makes possible

Core is not a one-time project. It is a platform Stash can keep building on.

It helps us improve:

• Personalization across the app

• Financial guidance and education

• Banking and investing connections

• Stock-Back® reward experiences

• Customer support resolution workflows

• Product testing and launch speed

• Operational controls and monitoring

The bigger idea is this: the financial industry often gives the best support to people who already have the most money. Stash is built against that. We believe everyday investors deserve thoughtful tools, plain-English education, and long-term guidance from day one.

Infrastructure is not the mission. But it can make the mission possible.

About Stash

Stash is an investing app built to help everyday Americans invest for the long term. Stash plans start at $3/month and include access to investing, education, guidance, and banking features provided by partners.

Stash is built around a simple investing philosophy: diversify, invest consistently, and think long term. You do not need to be a market expert to start building a portfolio. You need clear tools, plain-English guidance, and a strategy you can stick with.

About Stash Core

Stash Core is Stash’s custom-built backend technology platform. It allows Stash to own more of the ledgering, money movement infrastructure, rewards processing, and customer touchpoints behind the Stash experience.

Stash’s banking features, including the banking account offered through Stride Bank, N.A. and the refreshed Stock-Back® Debit Mastercard®, are designed to connect with Stash personal brokerage accounts and support The Stash Way.

The Stash Stock-Back patent, U.S. Patent No. 11,443,338, applies to backend technology that allows customers to earn specific securities and ETFs that are invested into their portfolio when they shop at eligible retailers in person and online. Terms apply.

About Stride Bank, N.A.

Originally chartered in 1913 as Central National Bank of Enid, Stride Bank, N.A. is an Oklahoma-based national bank regulated by the Office of the Comptroller of the Currency. Stride Bank provides banking and payment services, including debit card issuing and network sponsorship, for consumer and commercial programs.

Stride Bank, N.A. is a Member FDIC and an Equal Housing Lender. Learn more at www.stridebank.com.