Cloudflare open-sources a debugger for privacy protocols used by Apple and Microsoft, with AI agents in mind

Privacy relays like iCloud Private Relay work by splitting trust: one operator sees where a request comes from, another sees where it's going, and neither sees both. Apple runs one half, Cloudflare runs the other, and the whole point is that nobody, not even the two companies involved, can connect a user to a destination. That's the feature. It's also the reason debugging these systems is such a nightmare — the visibility engineers need to fix a broken request is exactly the visibility the protocol is designed to withhold.

Cloudflare just released a fix for that headache called pvcli, short for privacy-client, and put it out under an Apache 2.0 license so anyone can use it. It's a command-line tool for poking at Oblivious HTTP traffic today, with MASQUE support planned, and it's modeled on curl's syntax so it feels familiar to anyone who's spent time in a terminal. Cloudflare systems engineer Fisher Darling says the company built it after watching how painful onboarding new partners onto its OHTTP relay actually is — even when integrations technically work, as was the case with health app Flo Health, teams end up burning weeks chasing operational edge cases with manual scripts and guesswork.

The underlying problem is that split-trust infrastructure demands protocol expertise that only a handful of companies can justify building in-house. Apple and Microsoft can afford custom tooling. A startup trying to do the same privacy-preserving trick for, say, a health app or a finance product generally can't. Darling frames pvcli as leveling that field, letting smaller teams test against their own infrastructure or against a public sandbox called ohttp.info without first becoming OHTTP specialists.

What's more interesting than the tool itself is who it's designed for. Darling says pvcli was built explicitly for AI agents to run and reason about, not just humans typing commands one at a time. That's a deliberate bet tied to a bigger question Cloudflare is watching closely: as AI systems increasingly run inference on people's personal data, how do you keep that data from leaking to whoever's providing the inference? OHTTP is one piece of an answer that also involves confidential VMs and transparency logs, and Cloudflare clearly wants its debugging tooling ready for a world where agents, not engineers, are doing a lot of the troubleshooting.

Cloudflare quietly tested pvcli with an unnamed group of customers during a beta before this release, and Darling's pitch is broad — any company trying to separate identity from request content could use it, though he singles out health and finance as verticals where the stakes, and the regulation, are highest.