Calx

Privacy policy

Last updated 30 August 2026

This policy describes what Calx does with what you type and say. It is written to be read, not to be defensible.

The short version

Most calculations never leave your device. They are worked out on the phone, and nothing is sent anywhere.
When a question cannot be understood on the device, that question is sent to a model provider to be turned into a formula. This is the one case where what you typed leaves your phone. See below.
Nothing you type is ever sent to our analytics. We record that a calculation happened, never what it was.
There is no account, no email address, and no name. The app does not know who you are.

What leaves your device, and when

Questions we could not understand

Calx tries to answer every question on the device first. When it cannot — an unusual phrasing, or a sentence the built-in rules do not cover — the text of that question is sent to our server, and from there to Anthropic, to be turned into a mathematical formula.

Please read this part carefully. People use calculators for salaries, invoice totals, rent, margins and prices they are negotiating. If you type such a figure into a question the app cannot understand on its own, that question — including the numbers in it — is transmitted.

What is sent:

The text of the question.
The previous answer, if the question refers to it (“add 15% to that”).
A random device identifier (see below).

What is not sent: your name, your email, your phone number, your location, your contacts, your other questions, or anything the app answered on its own.

The formula that comes back is calculated on your device. The model never produces the number you see.

Who processes it: Anthropic, as our model provider, under their commercial terms. Requests are not used to train models.

How long it is kept: we store a one-way hash of the question so the same question is not paid for twice. A hash cannot be turned back into your question. We do not store the question text itself.

Voice

If you use the microphone, speech is converted to text by your device’s own operating system — Apple or Google, depending on your phone — under their privacy policies. Calx receives only the resulting text, and that text is then treated exactly like anything you typed: answered on the device where possible, and sent for interpretation only when it cannot be.

The microphone is requested the first time you tap the microphone button, never on launch, and refusing it leaves everything else working.

Crash reports

If the app crashes we receive a report describing where in the code it failed.

These reports are configured to exclude what you typed: the fields that could carry a question are stripped before the report leaves your device, and the logging of taps and typing that crash reporters normally do is switched off.

Who processes it: Sentry.

Analytics

We record exactly four things:

Event	What it means
first_calculation	You completed a calculation for the first time
day_two_return	You came back on a later day
interpretation_used	A question was sent for interpretation
paywall_shown	You reached the daily interpretation limit

No event carries the text of a question, an answer, or any figure. The count is the entire content.

Who processes it: PostHog.

Purchases

If you subscribe or buy the one-time unlock, the purchase is handled by the App Store or Google Play. We never see your payment details. We ask RevenueCat whether your device has an active purchase, using the same random identifier described below.

The device identifier

The app generates 16 random bytes the first time it runs and keeps them on your device. This identifier is used to count your daily free interpretations and to check whether you have paid.

It is not your advertising identifier and not derived from your hardware. It is meaningless outside our systems, cannot be linked to you, and cannot be used to recognise you in any other app. Deleting the app deletes it — a reinstall produces a new one and a fresh daily allowance.

What we never do

We never sell data.
We never use your questions for advertising.
We never send your questions to analytics.
We never ask for an account, and there is nothing to log in to.

Children

Calx is not directed at children and collects nothing that would identify one.

Your rights

Because there is no account, we hold nothing linked to your identity. If you want the device identifier and its usage counts deleted, delete the app, or contact us at hello@five6n.com and we will remove the record for an identifier you supply.

Where the GDPR applies, our lawful basis is legitimate interest in operating and protecting the service. Where the CCPA applies, we do not sell or share personal information as those terms are defined.

Changes

If this policy changes in a way that affects what leaves your device, the change will be described here and the date above updated.

Contact

Calx is published by:

Five6 North LLC30 N Gould St, STE RSheridan, WY 82801USA

Questions about this policy, about what the app holds, or a request to delete a device identifier: hello@five6n.com — five6n.com