Blog & developer journal
Behind the scenes of building a truly private location app.
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What your location history reveals about you
Where you sleep, work, pray and get treated, a few days of location traces expose more than most people imagine. And anonymisation barely helps.
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How Fenzly finds your friends without seeing your address book
Most apps upload your entire contact list to their servers. Fenzly never does, here's how consented hash matching finds your friends instead.
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Swiss data sovereignty: what it actually buys you
Fenzly runs on Swiss infrastructure under Swiss law. What that genuinely protects, where the limits are, and why encryption still does the heavy lifting.
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Why turning on backup isn't optional in Fenzly
Our server holds nothing readable and your Signal keys never leave your phone. That's the point, and it's why losing your phone without a backup is final.
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How unbreakable is Signal encryption, really?
A myth says a powerful enough computer can crack anything. For the encryption behind Signal and Fenzly, the numbers say otherwise.
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A location app that keeps working when your network doesn't
Most location apps go blank without a signal. Fenzly keeps working offline, only sharing with others is deferred until you reconnect. Here's why.
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The blind server: how a location app can't see your location
Fenzly's server stores only opaque encrypted blobs. Here's what it actually sees, what it can't, and the metadata we still can't make disappear.
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End-to-end encryption, explained without the jargon
What end-to-end encryption actually means, how the Signal protocol works, and why your location stays private in Fenzly.
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Building a genuinely private location app
Why we're building Fenzly, and what a "blind server" actually means.
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