Why your portfolio belongs on your device, not in the cloud
Many portfolio apps send your data to a server. Why client-side architecture is safer and how your portfolio data and API keys stay on your device.
TL;DR: Many portfolio apps store your data on their own servers — creating one central place that can be hacked. With a client-side approach, your portfolio data and broker API keys never leave your device: they're stored in the iOS Keychain, protected by the Secure Enclave. No server means no central prize for attackers.
Anyone managing their wealth through an app is sharing sensitive information: what you own, how much, and often a key to your broker. The question isn't only whether an app is safe, but where that data ends up. Here's why that difference matters.
Where do portfolio apps usually store your data?
Most portfolio trackers are cloud-based: your data — balances, positions, sometimes API keys — goes to the provider's servers so you can view it across devices. Convenient, but it means a copy of your financial profile sits outside your own device, in a place you don't control. That central store is exactly what attackers look for: one successful breach yields the data of every user at once. That's what's called a "honeypot".
What do "client-side" and "on your device" mean?
Client-side means the processing and storage happen on your device, not on a server. With David, your portfolio data and your broker API keys never leave your device. The keys are stored in the iOS Keychain, protected by the Secure Enclave — a separate, hardware-isolated chip in your iPhone designed specifically to safeguard sensitive keys. There is no server holding your positions or keys, so there is no central prize to steal.
One nuance for completeness: fund configurations — the settings of your funds, not your portfolio data — can sync via your own iCloud, so you find them again across devices. Your portfolio data and API keys stay device-only.
Is it safe to connect a Bitvavo API key to an app?
That depends on two things: what permissions the key has, and where the key is stored. You can restrict an API key — for example to reading and trading, without the right to withdraw funds. Never give an app more permissions than it needs. Equally important is where the key ends up: with David it stays in the iOS Keychain on your own device and does not go to a server. On top of that, always enable 2FA on your broker account.
Why should you care about this?
Because your financial data is among the most sensitive there is. A data breach at a cloud service can mean strangers know what you own — information that can be used for phishing, extortion or identity theft. The fewer places your data sits, the smaller that risk. "No server" isn't a marketing trick but an architectural choice that simply shrinks the attack surface.
Frequently asked questions
Is my portfolio data stored on a server somewhere?
With David, no. Your portfolio data and broker API keys never leave your device; they're stored in the iOS Keychain, protected by the Secure Enclave.
How does David Owl store my API keys?
In the iOS Keychain on your own device, protected by the Secure Enclave — a hardware-isolated chip. The keys do not go to a server.
Can a crypto app withdraw money with my API key?
Only if you grant the key that permission. Restrict your API key's permissions to what's needed and exclude withdrawal rights if you don't want to allow them.
Does David work across multiple devices?
Your fund configurations can sync via your own iCloud. Your portfolio data and API keys stay device-only and do not sync through a server.
Your data, your device
David is an iOS app that lets you manage your own fund while your portfolio data and API keys stay on your device. Read how we protect your data →
David Owl (C capital bv, Dutch CoC 82436665) is software, not a wealth manager, and offers no investment advice. Security also depends on your own settings, such as your API key's permissions and the use of 2FA.